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Evolution of Functional Appliances INDIAN DENTAL ACADEMY Leader in continuing dental education

Bionator Balters(1943) • The bulkiness of the activator and its limitation to nighttime wear lead to the development of Bionator which is a prototype of Muzy’s appliance. • Here the palate is free for propioceptive contact with the tongue and the buccinator wire loops hold away potentially deforming muscle action.

• Skeleton of the activator + Modification of Robin’s thoughts • According to Balters “ The equilibrium between tongue and cheeks, especially b/w tongue and lips in height, breath and depth in an oral space of maximun size and optimal limits, providing functional space, is essential for the natural health of the dental arches and their relation to each other ”

• Abnormal position of the tongue led to development of malocclusions : - Class II : Posterior displacement - Class III : low anterior displacement : - Narrow arches and crowding : low outward pressure - Open bite : hyperactivity and forward posture


He was in support of - Function and Form concept : Van der klaauw - Functional Matrix theory : Melvin Moss

• Aims of Rx : 1. Accomplish lip closure and establish contact b/w back of the tongue and soft palate 2. Enlarge oral space 3. Incisors in edge to edge 4. Elongation of the mandible 5. Leading to an improved relationship b/w the jaws, tongue, dentition and soft tissues

Bionator- types • Standard appliance :

• Open bite appliance

• Reversed/Cl III Appliance

Bimler Appliance (1949) • • •

Also referred to as : Gebissformer Oral adaptor Terminus technicus Activator – only night time use Bimler aimed at using small appliances which can be worn during the day time.

• Basic appliance : - Labial arch wire : Upper arch - Lingual arch wire : Lower arch - Joined together by small acrylic wings palatal wings palatal to the upper buccal segments.

• -

Additional wire elements U loop Springs

• Variations - Class A : class 2 div 1

• Class B : Class 2 div 2

- Class C : Class 3

Kinetor ( Hugo stockfish -1951 ) • Combination of Active and Myo-functional treatment methods • Muscular forces derived from the mandibular dislocation are joined with the active operation of screws and springs.

• As defined by Stockfish : “ The kinetor is a movable myofunctional bimaxillary plate which on account of kinetic energy of the oro-facial system retains rhe impulses in a sagittal, vertical and transverse directions which can then be utilised in the posterior region via springs, screws and elastic tubing b/w the upper and lower plates.”

Frankel’s Functional Regulator ( Rolf Frankel - 1960 ) • Marked a new phase of development in the evolution of functional appliances. • Created “ A revolution in orthodontic appliances ” - Charles nord • Frankel had a greater impact on American orthodontics than any other proponent of functional appliances.

• -

Conducted courses for : AAO G.V.Black Institute for continuing education Ann Arbor Orthodontic study club Kenilworth research foundation University of Chicago University of Detroit


Inspired by :

1. 2. 3. 4. 5.

Therapeutic Goal : Robin, Anderson-Haupl Dynamic functional orthopaedic approach : Bimler Use of additional wire elements : Eshler Elimination of damaging forces : Balters Broad based vestibular loops : Stockfish

Frankel philosophy:

• Potential restraining influence of the active muscle and tissue mass of the buccinator mechanism and the orbicularis oris complex • Artificial matrix allowing the muscles to exercise and adapt

• Exercise device: stimulates normal function, eliminating the lip trap, hyperactive mentalis, aberrant orbicularis oris and buccinator • Negative pressure of the muscles during deglutition is prevented • Bodily buccal movement of posterior teeth • Oral gymnastics: lip seal exercises

• Periosteal pull of buccal shields and lip pads increases bone activity • Stimulation of mid palatal suture growth lesser extent increasing bone apposition on the external subperiosteal layer of maxilla ( Stutzmann et al 1983, Graber et al 1991)

Dental effects: • Appliance anchored to maxillary arch; allows more downward and outward movement of upper teeth • Lower posterior teeth are allowed to erupt upward and forward; sagittal and vertical correction


In 1984 Frankel reduced his appliance to 4 basic types:

1. 2. 3. 4.

FR I : Class I / Class II Div I FRII : Class II Div I/II FR III : Class III FR IV : Open bite / Bimaxillary protrusions

Twin block Theraphy ( William J.Clark ) • Introduced in 1977 as a two-piece appliance resembling a Schwarz double plate and a split activator. • Further reviewed by clark ( 1982, 1988, 1995 ) • Replacement of occlusal inclined planes by means of acrylic inclined planes on bite blocks • Guide mandible downward and forward • Favorable propioceptive contacts of inclined planes. • Adaptation of the muscles of mastication

Advantages over other Functional appliances 1. Functional mechanism similar to natural dentition. 2. Occlusal inclined planes give greater freedom of movement in anterior and lateral excursions. 3. Less interference with normal function. 4. Improved appearance and function due to absence of lip, cheek and tongue pads. 5. Esthetically acceptable. 6. Can be worn 24 hrs. 7. Indepent control over upper and lower arch width.

Design • Occlusal bite blocks with inclined planes • Midline screws for expansion • Retention : Adams clasps Delta clasps • Interdental clasps on lower incisors • Labial bows on upper incisors : Continuous / split Active / Passive • Springs to move individual teeth • Provision for extraoral traction

Herbst Appliance ( Herbst -1909 ) • • •

First presented his fixed bite jumping device ( Scharnier ) – International Dental Congress-Berlin. Mandible continuously placed in a protruded position. Uses : ( Herbst, Schwarz – 1934 )

1. 2. 3. 4.

Cl II MO with Retrognathic mandibles. To facilitate healing after mandibular ramus fractures. As artificial joint after surgical removal of condylar head. TMJ problems – Clicking, Bruxism.

• •

Not well accepted and reintroduced by Pancherz( 1979) Indications : ( Pancherz )

1. 2. 3. 4. 5.

Cl II MO with Retrognathic mandibles. Postadolescent patients Mouth breathers Uncooperative patients Patients who do not respond to removable functional appliances.

• Since 1979 gained importance and led to the development of various fixed functional appliances.

Combined Extraoral and Functional Appliances • Class II div 1 with excessive vertical growth • Unloading of the condyle by forward posture of mandible • Retardation of horizontal and vertical maxillary growth by headgear

Varoius Appliances 1. 2. 3. 4. 5. 6. 7.

Spengeman (1967) Jacobson splint (1967) ACCO- Margolis (1976) Verdon appliance Stockli / Teuscher Clark Stockfish -

Hawley's retainer Hawley's retainer Modified activator Modified activator Twin block Kinetor

Magnetic Functional System ( Alexander D.Vardimon -1991 ) • Rationale for introducing magnets in FA is based on the necessity of decreasing the incidence of treatment failure associated with conventional appliances.

Advantages of Magnets 1. 2. 3. 4.

High force-to-volume ratio Maximal force at short distances 3-Dimensional orientation of magnetic force No interruption of magnetic force by intermittent media 5. No friction in attractive force configuration 6. No energy loss.

Etiology for treatment failure 1. 2. 3. 4.

Unfavourable skeletal growth pattern Inadequate patient compliance Incompetent neuromuscular adaptation Default differential diagnosis


Two Types of Functional Appliances 1. Activator, Postural hyperpropulsor, Frankel appliance, Twin block, Bionator, Class II Elastics(?) 2.

Herren activator, LSU activator, HarvoldWoodside activator, Extra oral traction on the mandible.


• Position mandible of Forward •

Increased activity LPM and RDP

LPM “helped to contract more” by Functional appliances.

• Chondroblasts lost

Increased multiplication of prechondroblasts

• Local control over multiplication of prechondroblasts originates from chondroblastic layer - Stutzmann and Petrovic (1982,1990)

Functional appliances

Increased activity of RDP Increased nutrients and growth factors supplied and inhibitors removed. Increased mitoses and earlier hypertrophy of chondroblasts.

Reduced negative feedback signal reaching prechondroblasts Increased growth at the condyle

Cytoplasmic junctions between skeletoblasts reduce.

Transmission of inhibitory factors reduce.

Increased mitotic rate and rate of differentiation into prechondroblasts.

SECOND GROUP: Position mandible forward , open in beyond rest position. No increase in activity of LPM •Herren (1953) •Auf der Maur (1978)

Yet there was an increase in growth

wo steps:

) While appliance is worn:Forward position Reduction of length of LPM New sensory engram

) While appliance is not worn:New sensory engram Functioning in anterior position Increased activity of RDP

Action of first group

while appliance is worn

Action of second

while appliance is not worn


CLINICAL IMPLICATIONS 1) Principle of optimality of function :Less relapse tendency if post orthodontic treatment muscular activity produces a lower deviation signal.

2) Removal of functional appliance – when growth is complete.

3) If removed when growth not complete – Proper intercuspation.

4) Understanding of when, and for how long a particular functional appliance should be worn. First group

– Full time

Second group – Part time

5) Proper functioning of LPM and RDP important for growth – Proper parent counseling. 6) Sensory engram poorly developed in younger children.

7) Utilization of high hormonal activity at puberty. Leader in continuing dental education

Evolution of functional appliances ortho/ dental implant courses by Indian dental academy  

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