Class II division 1 malocclusion: features and early intervention of

growing maxillary excess

Supervisor . Dr Maher Fouda

Prepared by Hawwa Shoaib

Prevalence of malocclusion of class 2 malocclusion.Cephalometric finding. Clinical findings.Interception of growing class2 division 1 malocclusion.

OVERVIEW

Class 2 malocclusion comprises agroup of specific skeletal. Dental and facial features. It is second in frequency. Distribution and prevalence among Angle’s malocclusion classes .

It is the most frequently encountered and treated malocclusion in orthodontic practice

Class 2 malocclusion is a synonym with distal position of the lower molar or mandible or protrusion of the maxilla and maxillary teeth or a variable combination

Prevalence

The prevalence of Angle’s class 2 malocclusion varies among population groups.. It is high among caucasians and lowest among the primitive races..

Class 2 malocclusions are observed in a wide – spectrum of presentation and severity …

Prevalence of class || malocclusion..

Clinical findings

• A distal step relationship 2nd deciduous molars is an indication of a devoloping class 2 malocclusion during the mixed dentition ..

Presentation during deciduous and early mixed dentition..

Mixed dentition Permanent dentition

Occlusal and craniofacial characteristics fromdeciduous to mixed dentition• Distal terminal plane of second deciduous molars . Large

over jet and overbite . • Narrow maxillary basal bone • Poor or no spacing in the deciduous dentition• Transverse discrepancy ( TD) between maxillary and

mandibular deciduous intermolar withs (2.8-1.1) mm compared to nil among normal occlusal groups .

• Retruded mandible and shorter mandibular length ( Co-Pg) on cephalometric examination

• The maxilla can also displaced forward in class || subjects with or without difference in the mandible ..

Occlusal and craniofacial characteristics fromdeciduous to mixed dentition

• It has been stated by Bishara et al that a distal step deciduous molar relationship is never self - correcting in growing children.

• Children with straight terminal plane may develop into a class | molar or class || molar relationship influenced by the mandibular growth pattern and adjustment of occlusion during the late mixed dentition .that would in clinical sense .

• Infer that when we encounter a class|| distal molar relation early in the mixed or permanent dentition.

• Some sort of interceptive measures may have to be undertaken or planned because nature would not take care

• During transition from deciduous to mixed dentition ,the craniofacial skeletal patteren shows an abnormal and variable patteren of growth in class || children compared to the control group of normal occlusion .

• The upper jaw becomes more prominent due to larger increments of maxillary protrusion relative to stable basal cranial structures .

• The mandible grows at a lesser pace than children with normal occlusion.

• A more backward and downward inclination of the mandibular body leading to a lesser decrease in the facial angle is seen .

• All this is coupled with a narrow maxillary base in the development of class || malocclusion .

• Other variations in class || subjects consist of contraction of the maxilla at both the skeletal and dentoalveolar levels and narrowing of the base of the nose.

• In general , the occlusal and skeletal features of class || malocclusion may remain stable or worsen to the stage of mixed dentition . There are certainly no favourable changes into a class | occlusion ..

Occlusal and craniofacial findings of class IImalocclusion during late mixed/permanent dentition stage

• A child with class II malocclusion presents with a protrusive mid-face and/or a retrusive chin. They often report with complaints of superior protrusion, front teeth jutting out or showing too much.

. Mid – face protrusive

Retrusive chin

This is often accompanied by a large overjet, deep bite (open bite can be seen in some) and a class II (distal) molar, premolar and canine relationship.

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Large over jet

Deep bite

These children have an aberrant pattern of muscle activity of the facial musculature such as a flaccid upper lip hyperactive mentalis and lower lip trap under the procumbent upper incisors.

Lower lip trap under the

procumbent upper incisors

The etiology may be attributed to mouth breathing/prolonged thumb sucking which can be elicited on carefully recording the history of the patient….

THUMP SUCKINGMOUTH BREATHING

The underlying craniofacial pattern of class II children has been extensively investigated. Most of the studies have concentrated on angular, sagittal and vertical measurements on lateral cephalograms. A few studies are also available ontransverse dimensions using PA cephalograms.

Cephalometric findings

PA. CEPHALOGRAMLAT. CEPHALOGRAM

A class II skeletal pattern may be associated with: prognathic maxilla retrognathic mandible or combination

of these in varying severity…

Prognathic maxilla

Rertognathic mandible

McNamara5 observed two types of skeletal combinationsin class II children. He found mandibular retrusion thesingle most characteristic feature which was attributed toenvironmental factors such as :

abnormal muscle function which altered occlusal interdigitations.

The skeletal maxillary protrusion was not the major finding. But was rather neutral. The 2nd was a combination of maxillary and mandibular skeletal retrusion, often in association with altered mode of respiration, i.e. mouth breathing.These children with maxillary and mandibular retrusion showed :

Greater vertical development of the

face

An excessive labial proclination and forward position of the maxillary anterior teeth is a common finding in class IIdivision 1 malocclusion.

The maxillary first molar is more mesially positioned ..

Class 2 division 1 , division 2 : the upper first molar mesially positioned.

The anterior segment of maxilla is moreprotrusive and superiorly positioned. Excessive anterior cranial base length and enlarged frontal and maxillary sinus may be a contributing factor in the development of class IIdiv. 1 malocclusion. The mandible and dentition were identical to those of the controls in size, form and position..

Moyers et al6 (1980) have identified six horizontal types of class II pattern which they designated: A, B,C, D, E and F. They identified five (1, 2, 3, 4, 5) vertical class II types ..

In brief, each case of class II malocclusion cannot be placed in a single category or type, and it may have a combination of sagittal, vertical and transverse deviations of varying severity. Hence, the treatment options may have to be considered accordingly and should be chosen as a function of disease entity. For type B and E, extraoral traction to maxilla is suggested while for C, D and F functional jaw orthopaedics is proposed….

Interception of developing class II malocclusion

Only limited orthodontic interventions are possible during

the deciduous dentition stage for the interception ofdeveloping class II malocclusion…..

Orthodontic interventions in class IImalocclusion during deciduous dentition :

Maintenance of healthy primary dentition.

All efforts are directed towards maintenance of the healthy primary dentition and thus integrity of arch length. This is achieved through education and home care by all the measures that minimize occurrence of dental caries.

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Restoration of carious teeth to their correct antero posterior dimensions is absolutely essential especially proximal carious lesions on deciduous molars.

The sole purpose is that permanent first molars should occupy the space distal to 2nd deciduous molars and should not prematurely migrate forward.

6E

Habits. Non-nutritive sucking habits such as prolongedthumb and finger sucking are taken care of with appropriatecounselling and interceptive habit breaking appliance. Achild with recurrent throat infection, nasal blockages orallergies should have ENT consultation to prevent mouthbreathing.

Mouth breathing ENT consultation

Orthodontic interventions in class IImalocclusion during mixed dentition..

1 - Cases involving essentially maxillary excess comparedto the mandible.

2 - Cases involving essentially mandibular retrusion.

Cases involving essentially maxillary excess compared tothe mandible. Involve guiding alveolar growth in class IIdivision 1 using headgear orthopaedic force.

Used in class 2 with open bite cases to intrude molars

Used in class 2 with deep bite cases to extrude molars

Kloehn (1953) was the earliest advocate of the use oforthopaedic forces to change positions of teeth and soinfluence the changes of the alveolar process in the maxilla.During normal craniofacial and alveolar growth, alveolusand teeth move forward and this can be intercepted. Thusif the maxilla is restrained in class II patients, mandible willfollow its normal growth and reach to a normal relation withthe maxilla.

A cervical headgear with a face bow is used torestrain maxillary growth and distalize the upper dentition toclass I dentition.

Components of a face bowKloehn cervical facebow consists of an inner bow of 0.045"diameter and an outer bow of 0.071" diameter. The inner bow fits in the round headgear tube on the first molarbands. Conventionally, a double buccal tube is welded andsoldered on to the maxillary first molar bands..

The inner face bow fits in the headgear tube on first molar bands Inner and outer facebow

the roundtube is housed as much gingival as permissible by the15° (10°-20°) to the inner bow to prevent distal tipping of the first molar crowns and prevent their extrusionThe inner bow is expanded, 8 to 10 mm larger than distance between first molar tubes, and made parallel to the occlusal plane.The ends of inner bows are bent inwards to prevent therotation of the first molars in their position.

A force 350 gm is used from cervical gear to the outer bow. The cervical headgear is recommended to be worn 12-14 hrs/day, in the evening and at night It usually takes about 12 months to achieve class I molar relation.improvement in over jet. This phase of orthopaedic correction is followed by full bonded fixed mechanotherapy

Age of treatmentKloehn facebow can be used in suitable cases wheremaxillary prognathism exists or mesial molar movement hasoccurred. The facebow is indicated in early mixed dentitionwhen permanent maxillary first molars have erupted and canbe banded.

Filho et al8 recommended the onset of treatmentin the late mixed dentition or beginning of the permanentdentition based on the belief that it often coincides with thefacial growth spurt. It may also have the advantage ofcontinuing the treatment with full-banded fixed appliance,following completion of 12 months of the first phase.

cervical traction is continued during/or till the end of activeclinical crown height. The purpose is to place it close to centre of resistance of the first molar which is near thetrifurcation of the roots. The inner bow has stops againstmolar tubes and are so adjusted that a space of 4-6 mm iskept between the bow and incisors. The stops can be eithersoldered or bent..

The outer face bow is extended to the tragus of the ear.The rigid outer bow is maintained at an elevation of abouttreatment to prevent relapse and enhance anchorage formaxillary anterior retraction/overjet correction

Effect o f cervical headgear on dental/craniofacial structures in sagittal, vertical andtransverse dimensions..

Following 12-18 months of treatment, there is a reduction in maxillary protrusion, while mandible continues to Grow normally. The distalizing effect on maxillary molars causes them to erupt backward and downward, thus inhibit loweringof the posterior region of the maxilla, while anterior region continues to move downward.

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There is a downward tippingof palatal plane at the anterior nasal spine (ANS). causes rotation of the palatal plane and slight increase inSN-PP angle. The inferior descent or extrusion of uppermolars is essentially prevented by the forces of occlusionfrom the masticatory muscles.

Transverse width of the maxilla improves from theexpanded inner bow, and allows an anterior displacement ofmandible and hence, improvement in the facial convexity.The maxillary protrusion is reduced while sagittal positionof the mandible improves, which is measured as a reductionin angle ANB. The improvement in craniofacial skeletal anddental profile is sustained during the period of fixed appliance therapy and post retention period.

Adverse effectsUnwanted side effects of Kloehn headgear can result fromthe use of this method of treatment in high angle cases,where molar extrusion and distal tipping may be significant.This coupled with unfavourable growth of mandible andclockwise rotation may bring about an undesirable outcome.The success of the treatment is fully compliance dependent.The appliance, if not worn correctly or in case of loosemolar band, breakage or welding failure of buccal tube(s),may cause injury of various kinds and severity.

Long-term effectsThe long-term effects of early headgear treatment on 8-yearfollow-up have shown that headgear treatment shows asignificant reduction in number of extraction treatment ascompared to controls. The appliance inhibits the growth ofthe maxilla and results in wider and longer arches. Its maineffect on maxilla is on the orientation of the maxillary plane.The maxillary arch expansion achieved during early headgear treatment results in a corresponding wide lower arch as anadaptation to maxillary arch.. The arch expansion has been found to be maintained during long-term follow-up

SummaryThe forward growing maxilla can be intercepted duringmixed dentition utilising orthopaedic forces in right direction and amount with Kloehn face bowThis modality of treatment was once very popular especially in USA. The appliance is effective however requires patient compliance..