Extraoral appliances

136
Extra oral appliances Rabab Khursheed

Transcript of Extraoral appliances

Page 1: Extraoral appliances

Extra oral appliances

Rabab Khursheed

Contents Introduction Principles classification History Types of head gear uses Biomechanics of headgear Clinical applications Effect of treatment with headgears Protraction face mask Types of facemask Biomechanics of facemask

Extraoral appliances or orthopedic appliances are used to modify the growth of maxilla and mandible using extraoral forcesThey are appliancersquos that provide a means of applying anterior posterior or vertical directed forces to the dentition and skeletal complex from an extra-oral source

bull There are essentially 3 alternatives for treating any skeletal malocclusion ndash

bull (i) growth modificationbull (ii) dental camouflagebull (iii) orthognathic surgery

bull Growth modification should be opted wherever applicable because this precludes the need for both tooth extraction and surgery

bull Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws

bull There are 3 types of orthodontic appliances that can be used for modifying the growth of maxillamandible-

(i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction

bull This seminar discusses the essential aspects of orthopedic appliances

ORTHODONTIC FORCE VS ORTHOPEDIC FORCE

bull There are 2 types of forces used in orthodontics-

1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement

2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth

Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude

Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites

Principles or Orthopedic appliances

1) Magnitude of force ndash

bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes

bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect

Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force

would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the

molar he felt the younger the patient the lesser the pressure to be applied

Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force

Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change

Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971

Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972

Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947

Baldridge unilatral traction with headcap angle orthod 3163681961

McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances

In combination system- 100grm cervical pull with 150grm high pull for anchorage

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 2: Extraoral appliances

Contents Introduction Principles classification History Types of head gear uses Biomechanics of headgear Clinical applications Effect of treatment with headgears Protraction face mask Types of facemask Biomechanics of facemask

Extraoral appliances or orthopedic appliances are used to modify the growth of maxilla and mandible using extraoral forcesThey are appliancersquos that provide a means of applying anterior posterior or vertical directed forces to the dentition and skeletal complex from an extra-oral source

bull There are essentially 3 alternatives for treating any skeletal malocclusion ndash

bull (i) growth modificationbull (ii) dental camouflagebull (iii) orthognathic surgery

bull Growth modification should be opted wherever applicable because this precludes the need for both tooth extraction and surgery

bull Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws

bull There are 3 types of orthodontic appliances that can be used for modifying the growth of maxillamandible-

(i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction

bull This seminar discusses the essential aspects of orthopedic appliances

ORTHODONTIC FORCE VS ORTHOPEDIC FORCE

bull There are 2 types of forces used in orthodontics-

1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement

2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth

Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude

Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites

Principles or Orthopedic appliances

1) Magnitude of force ndash

bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes

bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect

Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force

would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the

molar he felt the younger the patient the lesser the pressure to be applied

Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force

Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change

Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971

Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972

Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947

Baldridge unilatral traction with headcap angle orthod 3163681961

McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances

In combination system- 100grm cervical pull with 150grm high pull for anchorage

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 3: Extraoral appliances

Extraoral appliances or orthopedic appliances are used to modify the growth of maxilla and mandible using extraoral forcesThey are appliancersquos that provide a means of applying anterior posterior or vertical directed forces to the dentition and skeletal complex from an extra-oral source

bull There are essentially 3 alternatives for treating any skeletal malocclusion ndash

bull (i) growth modificationbull (ii) dental camouflagebull (iii) orthognathic surgery

bull Growth modification should be opted wherever applicable because this precludes the need for both tooth extraction and surgery

bull Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws

bull There are 3 types of orthodontic appliances that can be used for modifying the growth of maxillamandible-

(i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction

bull This seminar discusses the essential aspects of orthopedic appliances

ORTHODONTIC FORCE VS ORTHOPEDIC FORCE

bull There are 2 types of forces used in orthodontics-

1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement

2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth

Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude

Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites

Principles or Orthopedic appliances

1) Magnitude of force ndash

bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes

bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect

Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force

would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the

molar he felt the younger the patient the lesser the pressure to be applied

Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force

Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change

Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971

Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972

Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947

Baldridge unilatral traction with headcap angle orthod 3163681961

McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances

In combination system- 100grm cervical pull with 150grm high pull for anchorage

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 4: Extraoral appliances

bull There are essentially 3 alternatives for treating any skeletal malocclusion ndash

bull (i) growth modificationbull (ii) dental camouflagebull (iii) orthognathic surgery

bull Growth modification should be opted wherever applicable because this precludes the need for both tooth extraction and surgery

bull Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws

bull There are 3 types of orthodontic appliances that can be used for modifying the growth of maxillamandible-

(i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction

bull This seminar discusses the essential aspects of orthopedic appliances

ORTHODONTIC FORCE VS ORTHOPEDIC FORCE

bull There are 2 types of forces used in orthodontics-

1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement

2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth

Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude

Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites

Principles or Orthopedic appliances

1) Magnitude of force ndash

bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes

bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect

Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force

would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the

molar he felt the younger the patient the lesser the pressure to be applied

Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force

Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change

Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971

Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972

Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947

Baldridge unilatral traction with headcap angle orthod 3163681961

McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances

In combination system- 100grm cervical pull with 150grm high pull for anchorage

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 5: Extraoral appliances

bull Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws

bull There are 3 types of orthodontic appliances that can be used for modifying the growth of maxillamandible-

(i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction

bull This seminar discusses the essential aspects of orthopedic appliances

ORTHODONTIC FORCE VS ORTHOPEDIC FORCE

bull There are 2 types of forces used in orthodontics-

1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement

2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth

Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude

Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites

Principles or Orthopedic appliances

1) Magnitude of force ndash

bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes

bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect

Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force

would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the

molar he felt the younger the patient the lesser the pressure to be applied

Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force

Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change

Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971

Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972

Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947

Baldridge unilatral traction with headcap angle orthod 3163681961

McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances

In combination system- 100grm cervical pull with 150grm high pull for anchorage

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 6: Extraoral appliances

ORTHODONTIC FORCE VS ORTHOPEDIC FORCE

bull There are 2 types of forces used in orthodontics-

1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement

2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth

Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude

Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites

Principles or Orthopedic appliances

1) Magnitude of force ndash

bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes

bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect

Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force

would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the

molar he felt the younger the patient the lesser the pressure to be applied

Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force

Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change

Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971

Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972

Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947

Baldridge unilatral traction with headcap angle orthod 3163681961

McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances

In combination system- 100grm cervical pull with 150grm high pull for anchorage

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 7: Extraoral appliances

Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude

Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites

Principles or Orthopedic appliances

1) Magnitude of force ndash

bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes

bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect

Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force

would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the

molar he felt the younger the patient the lesser the pressure to be applied

Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force

Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change

Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971

Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972

Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947

Baldridge unilatral traction with headcap angle orthod 3163681961

McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances

In combination system- 100grm cervical pull with 150grm high pull for anchorage

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 8: Extraoral appliances

Principles or Orthopedic appliances

1) Magnitude of force ndash

bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes

bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect

Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force

would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the

molar he felt the younger the patient the lesser the pressure to be applied

Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force

Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change

Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971

Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972

Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947

Baldridge unilatral traction with headcap angle orthod 3163681961

McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances

In combination system- 100grm cervical pull with 150grm high pull for anchorage

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 9: Extraoral appliances

Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force

would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the

molar he felt the younger the patient the lesser the pressure to be applied

Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force

Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change

Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971

Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972

Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947

Baldridge unilatral traction with headcap angle orthod 3163681961

McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances

In combination system- 100grm cervical pull with 150grm high pull for anchorage

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 10: Extraoral appliances

McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances

In combination system- 100grm cervical pull with 150grm high pull for anchorage

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 11: Extraoral appliances

2) Duration of force ndash

bull Orthopedic changes are best produced by employing intermittent heavy forces

bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes

bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 12: Extraoral appliances

Poulton stressed on the point that the appliance should be worn atleast 12 hours a day

Armstone and watson suggested 22- 24 hours a day

Kloehn suggested 12-14 hours a day

Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 13: Extraoral appliances

Direction of force ndash

bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect

bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved

bull The force direction or force vector should be decided depending on the clinical needs

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 14: Extraoral appliances

4) Age of the patient ndash

It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt

Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 15: Extraoral appliances

Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years

Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years

Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 16: Extraoral appliances

In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo

Fletcher the age factor In orthodontics 1958

Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960

GraberOrthodontic forces- facts and fallacies Amj Orthod 1955

Block Headgear-modifications and admonition1954

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 17: Extraoral appliances

Types of extra oral appliance

The following are the commonly used orthopeadic appliances

Head gear Reverse pull facial mask Chin cup

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 18: Extraoral appliances

History Weinberger in his book ldquoOrthodontic review

evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23

The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855

Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars

Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion

Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 19: Extraoral appliances

In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear

As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 20: Extraoral appliances

Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances

The result was so rewarding that he continued this approach and brought it to the US

He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 21: Extraoral appliances

In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo

Biologic orthodontic therapy and reality Angle ortho 6157-167 1936

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 22: Extraoral appliances

Much credit must be given to Kloehn for reviving the use of extra oral appliances

He went on to combine the dental bow and facebow in a soldered joint

He also introduced the elastic neckstrap to apply traction

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 23: Extraoral appliances

High pull headgear also became famous to

a)Prevent mandibular rotationb)Attached to upper incisors to keep

them intruded and torqued while retracting them

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 24: Extraoral appliances

Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth

Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A

b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial

growth and development 1960

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 25: Extraoral appliances

In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted

a)There is no evidence that maxillary growth per se is affected

b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally

c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 26: Extraoral appliances

d)Marked improvement in basal relation can be obtained

e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 27: Extraoral appliances

Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 28: Extraoral appliances

Appliance designBasic element Force delivering unit ie facebow lsquoj-

hooksrsquo Force generating unit ie Elastic

springs Anchor unit ie Head cap neck pad

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 29: Extraoral appliances

Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are

Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth

Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 30: Extraoral appliances

Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance

The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 31: Extraoral appliances

Outer bow (wisker bow) Acts as a media through which force is

transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long

Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 32: Extraoral appliances

The outer bow can be short medium or long

Short ndash outer bow is lesser in length than inner bow

Medium ndash outer bow length is equal to inner bow

Long ndash outer bow is longer than inner bow

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 33: Extraoral appliances

Miscellaneous components Springs calibrated tension springs are

available These have the advantage that the applied force can be varied

Elastics serve as force elements and are available in the following forms

neck bands with strongmedium pull extra-oral plastic chains with length 119mm

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 34: Extraoral appliances

Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force

Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz

Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 35: Extraoral appliances

Cervical pull headgear Introduced by Kloehn in 1947 it is also known as

the kloehn headgear This was to become the most widely used form of

an extraoral traction appliance to be used in contempopary orthodontics

>

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 36: Extraoral appliances

Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear

Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 37: Extraoral appliances

High pull head gear The high-pull facebow is attached to

the maxillary first molars by means of an outer bow

>

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 38: Extraoral appliances

The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired

Rationale justifying the use of a high-pull headgear-

Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases

These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 39: Extraoral appliances

As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment

An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 40: Extraoral appliances

The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition

Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 41: Extraoral appliances

With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction

And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 42: Extraoral appliances

Treatment effects of the high-pull headgear include

intrusion and distalization of maxillary molars

Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 43: Extraoral appliances

Interlandi type headgear The interlandi type high pull

headgear In this design the outer bows

are attached to the head straps of the headgear with the help of frac12rsquo latex elastics

the direction of the applied force was modified by changing the point of attachment of these elastics

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 44: Extraoral appliances

In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar

The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar

a force of 500gmsside is used with recommended wear of 12 hrsday

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 45: Extraoral appliances

Combination facebow The cervical facebow and the high pull facebow

can be used in combination to alter the direction of force along the plane of the occlusion

Advocated by arm strong(1971) and berman(1976)

>

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 46: Extraoral appliances

J-hook headgear The forces produced by extraoral traction

also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire

Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 47: Extraoral appliances

Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)

J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth

Usually done in edgewise mechanotherapy

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 48: Extraoral appliances

Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 49: Extraoral appliances

Asher face bow demonstrated by roth

This is a high pull facebow with a headcap and a short intra oral bow

Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force

It applies force directly to maxillary canine brackets

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 50: Extraoral appliances

Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches

helps in intrusion of incisors

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 51: Extraoral appliances

Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)

They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 52: Extraoral appliances

Assymetricalunilateral headgears

Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 53: Extraoral appliances

The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches

Disadvantage-extended use of this device will tend to skew the arch to one side

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 54: Extraoral appliances

Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force

Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 55: Extraoral appliances

Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force

Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force

Said to minimise undesirable lateral force

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 56: Extraoral appliances

Biomechanics Centre of resistance- when

a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 57: Extraoral appliances

Centre of rotation-The centre of rotation is the point about

which the object rotates This varies with the location of the centre of resistance and the force applied to the object

Pure rotation occurs when the centre of rotation is at the centre of resistance

Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 58: Extraoral appliances

Location of the centre of resistance

a)Maxillary first molar- situated at trifurcation of the roots

Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36

b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest

Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 59: Extraoral appliances

Maxillary dental arch- between the roots of 1st and 2nd premolars

Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma

According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure

For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 60: Extraoral appliances

Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 61: Extraoral appliances

Greenspanrsquos study Greenspan in his study in 1970 gave

reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions

His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 62: Extraoral appliances

Cervical headgear

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 63: Extraoral appliances

When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow

If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 64: Extraoral appliances

If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases

If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 65: Extraoral appliances

The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth

Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 66: Extraoral appliances

High pull headgear

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 67: Extraoral appliances

This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap

The direction of the moment that is produced is dependent on the position of the outerbow

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 68: Extraoral appliances

If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise

On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction

The magnitude of this moment will be proportional to the distance of the outer bow to CR

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 69: Extraoral appliances

If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance

This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 70: Extraoral appliances

Straight pull Occipital headgear

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 71: Extraoral appliances

This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force

The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force

This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 72: Extraoral appliances

The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments

Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 73: Extraoral appliances

If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction

The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 74: Extraoral appliances

Vertical pull headgear The main purpose of this headgear is to

produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place

The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 75: Extraoral appliances

Treatment effects Extra oral traction has been shown to

produce a variety of skeletal and dento alveolar effects in class II patients

Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 76: Extraoral appliances

Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the

restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism

Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 77: Extraoral appliances

Maxillary dentoalveolar position

Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar

Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 78: Extraoral appliances

Mandibular dentoalveolar position

There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 79: Extraoral appliances

Mandibular skeletal position The antero-posterior relationship of the chin has

been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle

Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 80: Extraoral appliances

Vertical dimension There is no universal agreement as to

the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 81: Extraoral appliances

Mandibular plane angle and lower anteror facial hieght

An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators

An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 82: Extraoral appliances

A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars

In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 83: Extraoral appliances

Occlusal plane angle Investigators have differed as to the effect of

extraoral traction on the orientation of the occlusal plane relative to the cranial base

The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base

Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 84: Extraoral appliances

Palatal plane angle The palatal plane has been shown to

tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine

On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 85: Extraoral appliances

Transverse dimension In the literature changes in the transverse

dimension with extra oral traction has been minimal

Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 86: Extraoral appliances

Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 87: Extraoral appliances

Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion

Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 88: Extraoral appliances

Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation

They concluded that regardless of treatment taken vertical skeletal relationship was not affected

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 89: Extraoral appliances

Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt

They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 90: Extraoral appliances

Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients

Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals

Maxillary 1st molars continue to grow forward cranial base showed very little change

Mandibular plane angle did not increase appreciably with treatment

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 91: Extraoral appliances

Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 92: Extraoral appliances

Headgear with activator

Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment

Bass modified the appliance and used a J hook headgear

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 93: Extraoral appliances

The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws

Usage mainly limited to mixed dentition with force application of 250 grmsside

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 94: Extraoral appliances

Head gear with herbst appliance

First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment

High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period

Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 95: Extraoral appliances

Clinical Implications There are three main uses of headgear

force 1 Anchorage control2 Tooth movement3 Orthopedic changes

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 96: Extraoral appliances

Anchorage control In class II treatment headgear force can

play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted

Intraoral mechanics often result in eruption of teeth

Headgear produces a vertical force greater than the force of side effect

Inner and outer bows can be of any shape convolution and length

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 97: Extraoral appliances

Tooth movement Adjustment of outer bow such that a horizontal

force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping

Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 98: Extraoral appliances

Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch

High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment

120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is

necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical

Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be

achieved by asymmetric cervical headgear

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 99: Extraoral appliances

Orthopedic changes If the headgear is applied

through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 100: Extraoral appliances

If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected

Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 101: Extraoral appliances

Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior

curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla

As the force increases the stresses progress superiorly toward the body of the sphenoid bone

Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the

zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone

Cervical force produces more intensity at lower load level

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 102: Extraoral appliances

Junction of the maxilla with the lacrimal and ethmoid bones

Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid

Maxillary teeth High stresses around maxillary molars with

cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex

Also distal to second molar

Frontal process of maxilla Stresses produced anterior to nasolacrimal

foramen only with cervical pull

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 103: Extraoral appliances

Palate Cervical traction produces stress in posterior

region developing in the horizontal portion of palatine bones High pull has no effect

Anterior junction of left and right maxillae Only high pull produces forces below the anterior

nasal spine and just lateral to the suture between the two maxillae

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 104: Extraoral appliances

Sphenomaxillary suture- large compressive stresses

Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures

in particular resisted the posterior displacement of the complex

Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 105: Extraoral appliances

Maxillary protraction with mandibular growth restriction

The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism

HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time

Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 106: Extraoral appliances

Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change

Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 107: Extraoral appliances

Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance

Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 108: Extraoral appliances

Indications1 Growing patients having a prognathic mandible

and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal

shelves in cleft patients

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 109: Extraoral appliances

Sites of anchorage Anchorage from chin force is transmitted

to the condylar cartilage amp thus alters the growth of mandible

Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing

Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 110: Extraoral appliances

Biomechanical considerations

1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side

2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 111: Extraoral appliances

3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days

4 Frequency of use- 12 to 14 hours of wear a day

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 112: Extraoral appliances

Parts of a reverse pull headgear

1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is

connected to the rest of the face mask assembly by means of metal rods

2 Forehead cap use to derive anchorage from the forehead

3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement

4 Intraoral appliance traction hooks are placed either in the molar or premolar region

5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 113: Extraoral appliances

Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction

headgear is used Principle ndash pulling force on the maxillary structures with reciprocal

pushing force on the forehead or mandible through facial anchorage

A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more

>

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 114: Extraoral appliances

Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage

maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp

go vertically up from the angle of the mandible and end behind the ears

An elastic strap is attached to the end of the long arms to encircle the head

Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 115: Extraoral appliances

2 Face mask of Delaire Uses the chin and forehead for

support

Appliance is made up of a rigid wire framework which is squarish amp kept away from the face

It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 116: Extraoral appliances

Tubinger model

Modified type of Delaire face mask

Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose

The superior ends of the 2 rods house a forehead cap from which elastics

encircle the head

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 117: Extraoral appliances

4)Petit type of face mask

Modified Delaire face mask

Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup

A crossbar at the level of the mouth is used to engage elastics

Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient

An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients

VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 118: Extraoral appliances

Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)

Evidences Baccetti et al (1998) Significant skeletal effects of early

treatment of Class III malocclusions with maxillary expansion and face-mask therapy

Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change

Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 119: Extraoral appliances

Type of screw -HYRAX

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 120: Extraoral appliances

Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary

width has been obtained3 If patients do not need an increase in maxillary width the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary

complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3

appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if

growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of

the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 121: Extraoral appliances

Modification In 2005 Eric Liou et al introduced the

concept of ALT-RAMEC alternate rapid maxillary expansion and contraction

They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 122: Extraoral appliances

Skeletal and Dental effects of FaceMask therapy

Forward movement of maxilla and point A Reduction in mandibular projection

satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al

Sinclaire et al ndash there was a counterclockwise rotation of the maxilla

Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the

mandible

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 123: Extraoral appliances

Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device

that covers the chin and is connected to a head gear

Used to restrict the forward and downward growth of the mandible

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 124: Extraoral appliances

Types of chin cup1) Occipital pull chin cup ndash

Derives anchorage from the occipital and parietal region

Used in class III malocclusions associated with mild to moderate mandibular prognathism

Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 125: Extraoral appliances

2) Vertical pull chin cup ndash

Indicated in patients with steep mandibular plane angle and excessive anterior facial height

These patients usually exhibit an anterior open bite

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 126: Extraoral appliances

Fabrication Chin cups are fabricated individually for

the patient or pre- fabricated commercially available chin cups are used

The fabrication of chin cup requires an impression to be taken of the chin area

The cast is poured and the chin cup is fabricated using self cure acrylic resins

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 127: Extraoral appliances

Force magnitude and duration of wear

At the time of appliance delivery a force of 150-300 grams per side is used

Over the next 2 months the force is gradually increased to 450-700 grams per side

The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 128: Extraoral appliances

indications

1) Patients with mild skeletal prognathism of the mandible

2) In case of increased facial height

3) Patients who has well aligned or protrusive but not retroclined mandibular incisors

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 129: Extraoral appliances

Conclusion To obtain desired dento-skeletal effect

with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered

Different subjects may respond differently to same type of extra oral traction

Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 130: Extraoral appliances

Refrences Birte melsen and michel dalsta distal molar

movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria

OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371

Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 131: Extraoral appliances

Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442

RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107

Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 132: Extraoral appliances

Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65

Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243

Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386

Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 133: Extraoral appliances

Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249

Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145

Turner PJ Extra oral traction Dent update 199118197-203

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 134: Extraoral appliances

FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205

Graber TM Extra oral force- facts and fallacies AJO 195541490-505

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance
Page 135: Extraoral appliances

Patient compliance An important aspect of using extra oral

traction is whether appliance is being worn as instructed

Patients compliance can be improved if both parents and clinician provide motivation

  • Extra oral appliances
  • Contents
  • Slide 3
  • Slide 4
  • Slide 5
  • ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
  • Slide 7
  • Principles or Orthopedic appliances
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Types of extra oral appliance
  • History
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Classification of headgear
  • Appliance design
  • Slide 29
  • Slide 30
  • Outer bow (wisker bow)
  • Slide 32
  • Miscellaneous components
  • Slide 34
  • Cervical pull headgear
  • Slide 36
  • High pull head gear
  • Slide 38
  • Slide 39
  • Slide 40
  • Slide 41
  • Slide 42
  • Interlandi type headgear
  • Slide 44
  • Combination facebow
  • J-hook headgear
  • Slide 47
  • Slide 48
  • Slide 49
  • Slide 50
  • Slide 51
  • Assymetricalunilateral headgears
  • Slide 53
  • Slide 54
  • Slide 55
  • Biomechanics
  • Slide 57
  • Location of the centre of resistance
  • Slide 59
  • Slide 60
  • Greenspanrsquos study
  • Slide 62
  • Cervical headgear
  • Slide 64
  • Slide 65
  • Slide 66
  • High pull headgear
  • Slide 68
  • Slide 69
  • Slide 70
  • Straight pull Occipital headgear
  • Slide 73
  • Slide 74
  • Vertical pull headgear
  • Treatment effects
  • Anteroposterior dimension
  • Maxillary dentoalveolar position
  • Mandibular dentoalveolar position
  • Mandibular skeletal position
  • Vertical dimension
  • Mandibular plane angle and lower anteror facial hieght
  • Slide 83
  • Occlusal plane angle
  • Palatal plane angle
  • Transverse dimension
  • Slide 87
  • Slide 88
  • Slide 89
  • Slide 90
  • Slide 91
  • Slide 92
  • Headgear with activator
  • Slide 94
  • Head gear with herbst appliance
  • Clinical Implications
  • Anchorage control
  • Tooth movement
  • Slide 99
  • Orthopedic changes
  • Slide 101
  • Slide 102
  • Slide 103
  • Slide 104
  • Slide 105
  • Maxillary protraction with mandibular growth restriction
  • Slide 107
  • Slide 108
  • Indications
  • Sites of anchorage
  • Biomechanical considerations
  • Slide 112
  • Slide 113
  • Slide 114
  • Types
  • Slide 116
  • Slide 117
  • Slide 118
  • Influence of rapid maxillary expansion used with protraction HG
  • Slide 120
  • Technique
  • Modification
  • Skeletal and Dental effects of FaceMask therapy
  • Chin cup appliance
  • Types of chin cup
  • Slide 126
  • Fabrication
  • Force magnitude and duration of wear
  • indications
  • Conclusion
  • Refrences
  • Slide 132
  • Slide 133
  • Slide 134
  • Slide 135
  • Patient compliance