MYOFUNCTIONAL APPLIANCES

Prepared By: Shi--- IV year Part I B.D.S K.M.C.T. Dental College Kozhikode,Kerala

CONTENTS• INTRODUCTION -DEFINITION -HISTORY• BASIS FOR FUNCTIONAL

APPLIANCE• CLASSIFICATION• FORCES• TREATMENT PRINCIPLES• INDICATIONS• ACTION OF FUNCTIONAL

APPLLIANCES

• CASE SELECTION

• VISUAL TREATMENT OBJECTIVE

• COMMON APPLIANCES IN USE

• WHEN TO TREAT WITH FUNCTIONAL APPLIANCE?

• LIMITATIONS & COMPLICATIONS OF FAs

• CONCLUSION• REFERENCES

DEFINITION

• “ A removable or fixed appliance which favorably changes the soft tissue environment” -Frankel,1974

• “ A removable or fixed appliance which changes the position of mandible so as to transmit forces generated by the stretching of the muscles,fascia &/or periosteum,through the acrylic and wirework to the dentition and the underlying skeletal structures. -Mills,1991

“Loose fitting or passive appliance which harness natural forces of the oro-facial musculature that are transmitted to the teeth & alveolar bone through the medium of the appliance.”

HISTORY

• 1879-Norman Kingsley-Forward positioning of mandible in orthodontics-Bite plane/Bite-jumping appliance(vulcanite).Drawback-tendency to relapse even with bite guide.

1883- Wilhelm Roux-first to study the influences of natural forces and functional stimulation on form-foundation of both general orthopedic and functional dental orthopedic principles (Wolff’s Law).

• Ottolengui-removable plate

• 1902-Pierre Robin-first practitioner to use functional jaw orthopedics to treat a malocclusion-Monoblockin children with glossoptosis syndrome.

• 1909-Viggo Andresen(Denmark) -modified bite jumping appliance-inspired from Benno Lisher’s theory.

Viggo Andresen Karl Häupl

1938-Karl Häupl(Germany)-saw the potential of Roux’s hypothesis and explained how functional appliances work through the activity of the orofacial muscles.

• Andresen-Häupl associationACTIVATOR Biomechanical Orthodontics Functional Jaw Orthopedics Norwegian System.

1936-collaborated on a textbook Funktionskieferorthopädie (Function orthodontics).

• 1906-Alfred P. Rogers- Father Of Myofunctional therapy-the first to implicate the facial muscles for the growth, development,and form of the stomatognathic system.

The Original Herbst Appliance

Prof. Emil Herbst

1905/09- Emil Herbst - okklussionsscharnier / Retentionsscharnier Herbst appliance

•1949-Hans Peter Bimler-during WWII-incorporated elastic force to orthopedic appliance elastischer Gebissformer (elastic bite former) /adapter Bimler appliance.

~1938 -developed, the “roentgenphotogramm,” by superimposing a photograph on a head plate, to show the relationship between the skull, the teeth, and the soft tissues.

• 1956-Martin Schwarz- Double Plates combine the advantages of the activator and the active plate by constructing separate mandibular and maxillary acrylic plates that were designed to occlude with the mandible in a protrusive position.

Double Plates

1950-Wilhem Balters-Modified activator by reducing bulk from palate & substituted with a coffin spring Bionator

Prof.Dr.Wilhem Balters

Dr.Martin Schwarz

• 1957-Rolf Fränkel-Function Regulator.

• 1977-Dr.William J. Clarks-Twin Block

• 1989Magnetic Appliances-Blechman et al.

Prof.Rolf FrankelDr.William J. Clark

BASIS FOR FUNCTIONAL APPLIANCE

• “The three M’s-Muscles,Malformation and Malocclusion”-By Graber,1963-described effects of function & malfunction.

• The Functional Matrix Hypothesis by Melvin Moss

• Identification of certain cartilages(eg. Condylar cartilage) as secondary cartilages.

• Servosystem (or Cybernetic) Theory,1980, by Petrovic & associates

• Growth Relativity Theory(Vodouris & associates)

CLASSIFICATIONI. Classification by Tom Graber,when functional

appliances were removable: (i) Group I-Teeth supported -Eg: catlan’s appliance,inclined

planes.etc.

(ii) Group II-Teeth/Tissue supported-Eg:activator,bionator,etc.

(iii) Group III-Vestibular positioned appliances with isolated support from tooth/tissue-Eg:Frankel’s appliance,lip bumpers,vestibular screen

II. With advent of fixed functional appliances: (i) Removable Functionals-Eg: Activator, Bionator, Frankel’s (ii)Removable & Fixed-available in both removable & fixed

type-Eg: Twin Block,Herbst

(iii)Semi Fixed-Some components fixed,some detachable Eg: Den Holtz, Bass Appliance

(iv) Fixed- Eg: Herbst,Jasper Jumper,Churro Jumper,Saif springs,Mandibular Anterior Repositioning Appliance(MARA),etc.

III. With concept of hybridization by Peter Vig:

(i) Classical Functional Appliance-Eg: Activator,Frankel’s appliance

(ii)Hybrid Appliances-Eg: propulsor,double oral

screen,hybrid bionators,etc.

IV. Classification By Profitt (i) Teeth borne passive-myotonic appliances-Eg:

Activator,Bionator (ii) Teeth borne active-myodynamic applainces-Eg;

Bimler’s appliance, elastic open activator,Stockfish appliance

(iii)Tissue borne passive-Eg: Oral screen,lip bumpers (iv)Tissue borne active-Eg: Frankel’s appliances (v) Functional orthopedic magnetic

appliances(FOMA)

FORCES• Mostly use tensile forces-cause stress & strain-alter

stomatognathic muscle balance.

• Both external(primary) & internal(secondary) forces observed in each force application.

• External Forces-occlusal & muscle forces from tongue,lips & cheeks.

• Internal Forces-reactions of tissues to 10force

•They strain the contiguous tissues formation of osteogenetic guiding structure (deformation & bracing of the alv. process).This rxn important for 20 tissue remodelling,displacement and all other alterations that can be achieved by therapy.

•Differences in force application :-duration of force is interrupted (exceptions-Hamilton & Clark full-time-wear appliances & bonded Herbst & Jasper Jumper)-Magnitude of force is small.If induced strain is too great,difficulty in wearing the appliances.

TREATMENT PRINCIPLES

• Depending on the type of force applied,2 treatment principles can be differentiated:

I. Force Application II. Force Elimination

• In force application,compressive stress & strain act on the structures involved resulting in a 10alteration in form with 20 adaptation in function.

• In force elimination,abnormal & restrictive environmental influences are eliminated,allowing optimal development.Function is rehabilitated & followed by 20 adaptation in form.

INDICATIONS• Use of FA alone: -cases with mild skeletal discrepancy -proclined upper incisors -no dental crowding

• Use of FA in combination with fixed appliance: -used most commonly to improve the anteroposterior

relationship before starting the fixed appliance treatment.

-extremely useful in class II cases -reduce the amount of a comprehensive fixed therapy

required -reduce need for orthognathic surgery

• Interceptive treatment -early intervention indicated when one wishes to

utilize their growth enhancing effect. -extremely effective in reducing the relative

prominence of the proclined upper incisors,which are particularly susceptible to dentoalveolar trauma.

ACTION OF FUNCTIONAL APPLAINCES

• Skeletal,dento-alveolar & soft tissue effects of FA’s reviewed by Dare & Nixon(1999).

• Functional appliances can bring about the following changes:

(i) Orthopaedic Changes(ii) Dento-aveolar changes(iii) Muscular & Soft Tissue changes

• Orthopaedic Changes:-Capable of accelerating the growth in the condylar region.-Can bring about remodeling of the glenoid fossa.-Can be designed to have a restrictive influence on the growth of jaws.-Can change the direction of growth in jaws.

• Dento-alveolar Changes: -can bring about changes in sagittal,transverse &

vertical directions. -Inhibition of downward & forward eruption of the

maxillary teeth. -Retroclination of the upper incisors. -Proclination of the lower incisor. -Lower labial segment intrusion. -Levelling of the curve of Spee & tipping of the

occlusal plane.

• Muscular & Soft Tissues Changes: -improve the tonicity of the orofacial

musculature. -Removal of the lip trap & improved lip

competence. -Removal of adaptive tongue activity. -Lowering of the rest position of mandible. -Removal of soft tissue pressures from the

cheeks & lips.

CASE SELECTION

• Age: only in growing patient. Opt. age for FA therapy b/w 10 years & pubertal growth phase

• Social Considerations:• Dental Considerations: ideal caseone devoid of

gross local irregularities• Skeletal Considerations: Moderate to sever Class II

mo cases are ideal Mild Class III mo with a reverse overjet & an

average overbite

VISUAL TREATMENT OBJECTIVE

• An imp. diagnostic test undertaken before making a decision to use a functional appliance.

• Enables us to visualize how the patient’s profile would be after FA therapy.

• Performed by asking the patient to bring the mandible forward.

An improvement in profile positive indication. Profile worsensnegative-other Rx modalities considered.• Photographs taken with forward mandibular posture.

COMMON APPLIANCES

IN USE

VESTIBULAR SCREEN

• Introduced by Newell in 1912.• Takes the form of a curved shield of acrylic placed in the labial

vestibule.• Works on the principle of both force application & elimination.• Vestibular screen does not contact teeth as compared to oral

screen.

•Indications: -to intercept mouth breathing,thumb sucking,tongue trusting,lip biting & cheek biting. -mild disto-occlusions. -to perform muscle exercises to help in correction of hypotonic lip & cheek muscles. -mild anterior proclination.•Modifications:

HOTz MODIFICATION DOUBLE ORAL SCREEN(With additional tongue shield)

KRAUS’S MODIFICATION

To reduce bulk & allow expansion when required

Courtesy: The Orthodontic Cyber Journal

LIP BUMPER

• “combined removal-fixed appliance”.• Used in both maxilla & mandible to shield

the lips away from the teeth.Maxillary appliance Denholtz appliance.

• Uses:-in lip sucking patients.-hyperactive mentalis activity.-to augment anchorage-distalization of first molars

ACTIVATOR• Indicaitons: In actively growing individuals with

favorable growth patterns. -class II div I mo

-class II div II mo-class III-class I open bite-class I deep bite-as a preliminary T/t before major fixed appliance therapy to improve skeletal jaw relations.-for post treatment retention-children with lack of vertical development in lower facial height.

• Contraindications:-correction of class I cases with crowded teeth caused by disharmony b/w tooth size & jaw size.-in children with excess lower facial height.-in children whose lower incisors are severely procumbent.-in children with nasal stenosis caused by structural problems w/in the nose or chronic untreated allergy.-in non-growing individuals.

• Advantages:

-uses existing growth of the jaws-minimal oral hygiene problems-intervals b/w appointments is long-appoints are short,minimal adjustments required-hence,more economical

• Disadvantages:

-requires very good patient cooperation-cannot produce a precise detailing & finishing of occlusion.-may produce moderate mandibular rotation(hence contraindicated in excess lower facial height cases)

• Mode Of Action: Acc. To Andresen & Haupl

-induce musculoskeletal adaptation by introducing a new pattern of mandibular closure. stretching of elevator muscles of masticationcontractionmyotactic reflex set up kinetic energy which causes: -prevention of growth of max. dento- alveolar process -movement of max. dento alveolar process distally -reciprocal forward growth of mandible.

• In addition, a condylar adaptation by backward & upward growth occurs.

• Modifications:

BOW ACTIVATOR By A.M.Schwarz

Wunderer’s modificaiton for Class III

PROPULSOR by Muhlemann & Hotz

REDUCED ACTIVATOR/KYBERNATOR By G.P.F.Schmuth

Herren’s Modification

Type I - Distal Activator

Type II - Prognathism Activator

KARVETZKY

MODIFICATION

KARVETZKY

MODIFICATION

Type III a Pan Activator

Type III b Pan Activator

• Wear Time:1st week 2-3 hrs a day during day time 2nd week onwards 3 hrs during day & while sleeping.

FRANKEL’S FUNCTION REGULATOR

• 2 main T/t effects:1) serves as a template against which craniofacial muscles function. Framework of the appliance provide an artificial balancing of environment.

2) removes the muscle forces in the labial & buccal areas thereby providing an environment which enables skeletal growth.

• Types:FR I-Class I & Class II Div I . FR 1a-Class I with minor to moderate crowding. FR 1b-Class II div I where overjet does not exceed 5mm FR 1c-Class II div I ;overjet >7mm

• FR II- Class II div I & II

• FR III-Class III• FR IV-open bite & bimaxilliary protrusion• FR V- incorporate head gear. Indicated in long face

patients having high mandibular plane angle& vertical maxillary excess.

FR III FR IV

BIONATOR• Developed by Balters in 1950’s.• Modified activator less bulky & more elastic• 3 types-

> Standard type-class II div I having narrow dental arches> Class III Appliance>Open bite appliance

Standard type

Class III Appliance Open Bite Appliance

TWIN BLOCK APPLIANCE

• The Twin Block appliance is a removable, orthodontic functional appliance that is used to help correct jaw alignment, particularly an underdeveloped lower jaw.

• Developed by Dr.William J. Clarks , 1977.• Effectively combines inclined planes with

intermaxillary & extraoral traction.

• The removable twin block is a tissue-born functional appliance that is worn fulltime. It helps in the advancement of the mandible. It is a two-piece appliance composed of an upper and lower bite block. Orthopedic traction can be added in cases of severe skeletal discrepancies. This includes the use of a Concord Facebow (or headgear) at nighttime. Upper & lower bite blocks interlock at 700 angle.

• The fixed twin block is similar to the removable twin block, but can be used in non-compliant patients. It is similar in design to the Herbst appliance, however the telescopic tubes of the Herbst appliance are replaced with two bite blocks.

• Advantages:-very good patient acceptance.-bite planes offer greater freedom of movement & lateral excursion.-less interference with normal function.-significant changes in patient’s appearance within 2-3 months.

HERBST APPLIANCE

• Fixed functional appliance developed by Emil Herbst in early 1900’s.

• Indications:-correction of class II MO due to retrognathic mandible.-can be used as anterior repositioning splint in patients having TMJ disorders.

• Specific indications-Post adolescent patients: T/t completed w/in 6-8 months,hence possible to use the residual growth in these patients.-Mouth breathers-Uncooperative patients

• 2 types:-Banded Herbst -Bonded Herbst

Banded Herbst Appliance

Bonded Herbst Appliance

• Advantages:-continuous action-T/t duration is short-less pt cooperation needed-can be used in pts who are at the end of their growth-can be used in pts with mouth breathing habit.

• Disadvantages:-cause minor functional disturbances.-increased risk of development of dual bit,with TMJ dysfunction symptoms as a possible consequence.-repeated breakage & loosening of appliance occurs,esp. in lower premolar area.-plaque accumulation & enamel decalcification can occur-tendency for posterior open bite.

JASPER JUMPER

• A relatively new flexible,fixed ,tooth borne FA.

• Introduced by J.J.Jasper ,1980• Actions similar to Herbst appliance but

lack rigidity.• Basically indicated in skeletal class II mo

with max. excess & mandibular deficiency.

• Advantages:-produce continuous force-does not require patient compliance-allows greater degree of mandibular freedom than Herbst appliance-oral hygiene is easier to manage.

WHEN TO TREAT WITH FUNCTIONAL APPLIANCE ???

• The best time to start functional appliance therapy is the late mixed dentition.

• Advantage of the pubertal growth spurt should be taken.

• Girls & boys along with early maturers should be assessed individually.

LIMITATIONS & COMPLICATIONS• Discomfort, as both upper & lower teeth

are joined together.• Mainly depends on patient’s compliance• Can be used only if a favorable horizontal

growth pattern is present in cases of Class II correction.

• It has to be removed during masticaiton,particularly when strongest forces are applied.

• May interfere with speech.• Treatment duration is often long

CONCLUSION• The global demand for orthodontics without braces

continues to grow.  It's an option that many parents and patients would prefer.

• Myofunctional orthodontics offers a viable alternative to traditional orthodontic methods.

• A functional appliance is an appliance that produces all or part of its effect by altering the position of the mandible/maxilla.

• These appliances utilize the muscle action of the patient to produce orthodontic or orthopaedic forces to restore facial balance.

• The question that must be addressed in diagnosis is : “does the patient require orthodontic treatment or functional orthopedic treatment or a combination of both and to what degree?whether the patient requires functional appliance alone or need a orthognathic surgery or to what extend FA can reduce need for surgery?”

“ The study of orthodontia is indissolubly connected with that of art as related to the human face.The mouth is a most potent factor in making the beauty and character of the face and the form & beauty of the mouth largely depends on the occlusal relations of the teeth.Our duties as orthodontists force upon us great responsibilities and there is nothing which the student of orthodontia should be more keenly interested than in art generally,and especially in its relation to the human face,for each of his efforts,whether he realizes it or not makes for beauty or ugliness,for harmony or inharmony,for perfection or deformity of the face.Hence it should be one of his life studies. ” - E.H.Angle,1907

REFERENCES

1) Dentofacial Orthopedics with Functional Appliances by Thomas M. Graber,Thomas Rakosi & Alexandre G.Petrovic;2/e,2009

2) Orthodontics Diagnosis & Management of Malocclusion & Dentofacial Deformities by Om Prakash Kharbanda;2/e,2013

3) Orthodontics Principles & Practice by Basavaraj Subhashchandra Phulari;1/e,2011

4) Textbook Of Orthodontics By Gurkeerat Singh;2/e,2007

5) Textbook Of Pedodontics by Shobha Tandon;2/e,2008

6) Orthodontics –The Art & Science by S.I.Bhalajhi;3/e,2003

7) Contemporary Orthodontics by William R.Proffit;4/e,2007

8) Norman Wahl,Special Article, “Orthodontics in 3 millennia. Chapter 9: Functional appliances to midcentury”;(Am J Orthod Dentofacial Orthop 2006;129:829-33)

9) Various Internet Sources