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Transcript of Functional Appliances (2nd Round) - Dr Khadra
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Functional Appliances
An Overview in Using Functional Appliances in
Treating Class II
Thamer Alkhadra BDS, MS
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Skeletal Class II
• Maxillary (upper jaw) protrusion
• Mandibular (lower jaw) retrusion
• Combinations of both
• The majority of the Class II malocclusions
have normal maxilla and retruded mandible
(McNamara 1981; Pancherz et al. 1997)
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Skeletal Class II treatment
• Growth adaptation
�Children/adolescents
• Camouflage-orthodontics
�Post adolescents
• Surgical correction
�Adults
(Pancherz 2000)
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Orthodontic Appliances
• Fixed appliances
• Removable appliances
• Functional appliances
– Removable (activator, bionator)
– Fixed (Herbst appliance)
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Definition
• A functional appliance is an appliance that produces all or part of its effect by altering the position of the mandible
• It is one that changes the posture of the mandible, holding it open or open and forward
• Nearly all functional appliances are removable
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Functional appliances
• They do not act primarily on teeth like conventional appliances (springs, elastics)
• They transmits, eliminate or guide natural forces
• Natural forces that can be controlled by functional appliances are: muscle activity from the tongue and check, tooth eruption, and growth and development
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Functional appliances
• Removable (activator, bionator,
Fränkel II)
• Fixed (Herbst appliance)
• Affecting mandibular growth & position
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Functional Appliance
• Performed during the main growth
period around puberty
• The most favorable age for therapy
– 8-11 years for girls
– 10-13 years for boys
(Pancherz 2000)
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Types
• Tooth-borne passive
• Tooth borne active
• Tissue borne
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Tooth-borne passive
• No intrinsic force generating capacity from springs or screws and depend only on soft tissue stretch and muscular activity to produce treatment effects
• Andersen Activator
• Woodside and Harvold Activator
• Bionator
• Herbst appliance
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Tooth Borne Active
• Modified Activator (many named types)
• Expansion Activator
• Orthopedic corrector
• Stockli headgear Activator
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Tissue Borne
• Frankel Appliance
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The Anderson Activator
• Fits loosely• Advances the mandible forward • Uses moderate opening of vertical dimension
• Incorporate a labial bow for control of maxillary anterior teeth
• An acrylic cap over lower incisors• Facets cut in the acrylic help direct eruption of posterior teeth
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The Woodside & Harvold Activator
• Increase vertical opening to help maintain the appliance in the mouth during sleep by stretching the soft tissue
• The mandible is advanced so that the incisors are in edge-to-edge relationship
• Maxillary teeth are prevented from eruption
• Mandibular teeth are free to erupt upward and forward
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Tooth-Born Active Appliances
• These are largely modifications of activators and bionators
• It include expansion screws, springs to provide intrinsic forces for transverse and anterioposterior changes such as expansion activators, orthopedic corrector
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The Expansion Activator
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The Orthopedic Corrector
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The Stockli-type Activator
• Tooth-borne appliance that attempts to reduce undesirable dental changes with the addition of high pull headgear and torquing springs
• Vertical anterior torquing springs to reduce lingual tipping of maxillary incisors
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The Stockli-type Activator
• Headgear will restrict the horizontal growth of the maxilla
• The acrylic prohibits posterior maxillary eruption and allow mandibular eruption
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Functional Appliance Components
Functional components
• Lingual pad or flanges
• Lip pads
• Buccal and lingual shields
• Occlusal or incisal stops
• Sliding pin and tube
• Facets or flutes
• Displacing springs
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Functional Appliance Components
Active components
• Labial bow
• Headgear tube
• Torquing springs
• Expansions screw and spring
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Functional Appliance Effects on Teeth (in general)
• Tipping of mandibular incisors facially
• Retract maxillary incisors
• Allow of eruption and mesial movements of mandibular molars
• This result in increase lower facial height
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Bionator
• Developed first by Wilhem Balters (1964)• The most commonly –used removable functional appliance today• It is a generic terms that refers to a family of appliances used to treat malocclusions, characterized in part by mandibular deficiency
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Bionator
• The bionator produces a forward positioning of the lower jaw
• The acrylic parts of the bionator contact the teeth and supporting structures, thus creating changes in the skeletal, dentoalvelor and muscular environment of the craniofacial region
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Bionator
• It is a cut down activator
• Less bulky than activator
• Easily accepted by parents and patients than activators
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Bionator
• Many modification have been introduce to the bionator
• Due to limited amount of acrylic used in construction in comparison to the activator, more normal speech patterns can be maintained by the patient compared to wearing activator appliance
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Bionator
• Vertical control is present
• Uses a lingual flange to regulate the posture of the mandible and usually incorporates a buccinator wraparound or labial bow
• The design can include posterior facets or acrylic occlusal stops to control amount and direction of eruption
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Advantage of the Bionator
• Less prone to breakage
• Relative ease of fabrication
• Relative ease in clinical handling
• It could be used with simultaneous fixed appliance Tx
• Not as effective with patients suffering from significant neuromuscular imbalance where FR-2 is indicated
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Types of Bionator
• Bionator to open the bite
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Bionator to close the bite
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Bionator to maintain the bite
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Rick-a-nator
-Designed by Gallaher-To Tx patients who are non-complianceOr who have difficulties in wearing removable appliances-It consist of maxillary inclined plane, which hold the mandible in the desired AP position
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Frankel II
� In Tx of Cl II malocclusion characterized in part by mandibular skeletal retrusion
� Greatest effect on skeletal dentoalveolar and muscular component
� Unique by been tissue-borne rather than tooth-borne
� Base of operation is the maxillary and mandibular vestibule
� Direct and primary effect on the neuromuscular system
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FR_2
� first is used as an exercise device in retraining the associated musculature and indirectly producing changes in skeletal and dentoalveolar relationship by reprogramming the CNS
� interrupts abnormal patterns of muscle activity
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FR_2
� ultimately produces an environment in which skeletal and dental arch changes occurs
� increase in mandibular length
� increase in transverse dimensions of dental arches
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� appliance of choice in the TX of patients with severe neuromuscular imbalances and skeletal discrepancies
� tissue-borne appliance – maximum skeletal changes archived with minimal unwanted tooth movement
� protecting effect of vestibular shield on dentition – spontaneous expansion in both arches occurs
� optimizing the development of the orofacial structures , in part, by “removing restrictions or retarding in the accomplishment of growth pattern
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FR_2
Anteroposterior dimension
� Max skeletal position
– no or minor influence
� Max dentoalveolar position -
- horizontal molar movement-slightly restricted
- vertical molar movement-unaffected
- slight lingual tipping of U1
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FR_2
� Mand dentoalveolar position
- additional vertical molar movement
- lower incisors proclination ( freed from behind the lower lip)
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FR_2
� Mand skeletal position- Pog moves forward- mandibular growth- increase in posterior facial height- Y-axis closed – more horizontal vector of growth
� Vertical dimensions- increase in lower anterior facial height� Transverse dimensions- average in expansion of dental arches:max 4-5mm mand 3-4mm
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TWIN BLOCK APPLIANCE
• Developed by Clark in 1977
• Has no direct effect on musculature
• Perceived by most clinicians to be easier to manipulate than FR-2
• Class II correction can achieved readily within a 6-9 months period
• Easy for the patients for adaptation
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TWIN BLOCK APPLIANCE
• Composed of removable MAX and MAND separates unattached plates that fit tightly against the teeth , alveolus and supporting structure
• Full time appliance (including during meal )
• Control of vertical dimensions
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TWIN BLOCK APPLIANCE
• MAX plate , with one or two midline screw – if expansion needed
• Bilateral bite blocks are located: posterior – in the maxillary appliance and anterior –in the mandibular appliance
• The inclined planes of the posterior bite blocks are oriented at 70 degrees to the occlusal plane to initiate functional shift of the mandible and to open the closed bite
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TWIN BLOCK APPLIANCE
• The 2 screws – gives a stability for appliance ( specially for patients with significant expansion needed )
• Clark : saggital screw if retroclination of Max incisors
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Original (Clark’s) design
- Horseshoe of acrylic that extends posterior to the mandibular second premolars- Molars not contacted by acrylic to allow for eruption- Ball clasps
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Modified (McNamara’s)
design
- Labial bow placed anterior of mand incisors
- Posterior extension to the first and second molars but not occlusal coverage
- Mand block originate in the mand canine region
- Gradually increase in height posterior
- Occlusally – to 2nd premolars
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TWIN BLOCK APPLIANCEEFFECT OF TREATMENT
• Increase in MAND length• Distalization of the MAX molars• Eruption of the MAND molars• Tipping of the anterior incisors : proclination - mandibular, retrusion -maxillary.
• Increase in anterior and posterior facial height
• Inhibition in MAX growth
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Advantage of twin block therapy
� Ability to manipulate the vertical
dimension
-Improved patient cooperation
- Easy for adaptation
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The Herbst appliance
• Described first by Herbst (1900)
• It was on of the early attempts to
produce mechanically “jumping of the
bite”
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The Herbst appliance
• Original banded design was
introduced by Herbst at the
International Dental Congress in
Berlin in 1905
• Popularity diminished
• Reintroduction in 1979 by Pancherz
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The Herbst Appliance
• Keeps the mandible continuously in a
protruded position, both on jaw closure and
when the teeth are not in occlusion
• Cast metal skeleton splints were cemented
to both upper and lower arches
• Once placed by the operator, cannot be
removed by the patient
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MAX skeletal
- Minimal short term effect - Inhibition of midfacial length (McNamara)
MAX dental
1.Molars; upward and backward vector of force - molars distalization- molar intrusion - distal crown tipping 2.Incisors - remains unchanged
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• Mandibular molars- mesial movement (1-2mm) - extrusion
• Mandibular incisors - proclination- intrusion
• * The crown Herbst appliance produces greater proclination of lower incisors than acrylic splint Herbst appliance
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Advantage of the Herbst
– Fixed to the teeth and no co-operation
from the patient is required
– It works 24 hours a day
– Treatment time usually short (about 6 to
8 months)
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Clear Herbst
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Wax Bite
• A proper wax bite must be provided• The mandible must be brought forward until the lower anterior are labial to the upper anterior by 1- 2 mm or edge to edge depending on the technique
• Posterior separation of 6-7mm to open bite• Posterior separation 3-4mm to close or maintain bite
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Before & After
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Before & After
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International Symposium on Early Orthodontic Treatment, Phoenix, AZ 02/02
(Turpin. AJO-DO April 2002)
• The range of possibility for correcting Class II problems remain fairly broad
• Proffit reported the results of the long-term prospective study of class II correction “there are no significant differences in the treatment results”
• Lysle Johnston supported these finding • Bremen, Pancherz in AJO-DO Jan 2002 reported “Class II Div I treatment was more efficient in the permanent dentition than it was in the early or late mixed dentition” considering better outcome and shorter treatment time
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Literature Review• De Almeida et al. AJO 2002 reported in their study that The major treatment effects of bionator and FR-2 appliances were dentoalveolar, with a smaller, but significant, skeletal effect. Both appliances produced similar labial tipping and protrusion of the lower incisors, lingual inclination, retrusion of the upper incisors, and a significant increase in mandibular posterior dentoalveolar height
• Mills CM et al. (AJO 2000) reported in their study of twin block with expermental and control group that the control group experienced a 2.3 mm increase in mandibular unit length during the 13-month observation period (annualized rate of 2.1 mm per year). In the posttreatment phase, the change in mandibular unit length for the Twin Block group was 6.0 mm over a 36-month period (annualized rate of change of 2.0 mm per year)
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Literature Review
• A study comparing FR2 and twin block showed more extensive dentoalveolar adaptation that was observed with the tooth-borne Twin-block appliance than with the more tissue-borne FR-2. The Twin-block and FR-2 samples both showed significant retroclination and extrusion (eruption) of the maxillary incisors (Toth LR, McNamara JA Jr. 1999, AJO)
• Ghafari support a one-phase treatment starting in the late mixed dentition. “Earlier intervention in mid-childhood may be required in the presence of several developmental conditions, or when the dental and skeletal development deviate significantly in the individual patient” (Clin OrthodRes 1998)
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Literature Review
• The Herbst method is most effective in the treatment of Class II malocclusions. Long-term stability seems to be dependent on a stable cuspalinterdigitation. Marked mandibular morphological changes occur during therapy and sagittal condylargrowth is increased. The appliance effect on the maxillary complex can be compared with that of a high-pull headgear. Without proper retention, however, this effect is of a temporary nature (Pancherz Seminar in Orthodontics 1997)
• Ghafari in his control study compared FR2 and headgear and found no difference.Treatment in late childhood was as effective as that in midchildhood (AJO 1999)
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Thank You