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-Monoblockin 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 associationACTIVATOR
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
• 1989Magnetic Appliances-Blechman et al.
Prof.Rolf Frankel
Dr.William J. Clark

BASIS FOR FUNCTIONALAPPLIANCE
• “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)

CLASSIFICATION
I. 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 10
force

•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 10
alteration 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 FUNCTIONALAPPLAINCES
• 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

-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.

-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.

-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 caseone 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 worsensnegative-other Rx modalities
considered.
• Photographs taken with forward mandibular posture.

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
masticationcontractionmyotactic 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
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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 70
0
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

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