Functional Appliance

and

The Mode of Action

By :

Islam Yehia

Raghed Michael

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

• The most favorable age for therapy

– 8-11 years for girls

– 10-13 years for boys

Why treat malocclusion?

• Possible pre-disposition to disease

• May lead to jaw dysfunction

(TMD, Speech, Mastication)

• Facial esthetics with psychological effects

• Single or multiple tooth damage

Indications for functional

Appliances

• Well aligned dental arches

• Posterior positioned mandible

• Non severe skeletal discrepancy

• Lingual tipping of mand. incisors

• Proper patient selection

History of development of

functional appliances

• Robin 1902- monobloc

• Andresen 1908- Activator

• Herbst 1934- Herbst

• Balters 1960- Bionator

• Bimler 1964 – Bimler

• Frankel 1967- Frankel

• Clark 1977-Twin Block

Historical biases of Europe and

America on functional appliances

European

• Functional approach most

biocompatible

• Mechanical force deemed

unbiologic

American

• European social system

excluded extensive fixed

appliance therapy

• Question of precision of results

Duration and timing of wear

• Functional appliance treatment

should be started before the

pubertal growth spurt.

• This is the time when the

mandible may exhibit increased

growth which may be influenced.

• Functional appliances should be

worn for at least 10-12 hours a

day.

Night Time

VS

Day Time

Growth

Theories

Scott’s

Cartilaginous

Growth Theory

Sitcher’s

Sutural Growth

Theory

Moss’s Functional Matrix Theory

Form

follows

function

Polyvinyle sialoxane bite registration material

Polyvinyle sialoxane bite

registration material

Wax bite material

preformed to arch shape

Activator

Woodside & harvold

activator

Herbst

Bionator

Activator facts

• Tooth borne passive appliance • Original design worn at night

• Large one piece of acrylic

• Teeth could be redirected during eruption

• Large vertical opening construction bite

• Could not speak or eat when worn

• Advances mandibular jaw

• The original andersen activator was designed with

angled flutes to guide the eruption of the molars for the

upper molars distally and the lower molars mesially as

they erupt

• New design

• Lingual flanges contribute to its action

• Upper cant erupt

• Lower free to erupt

• Rotation of occlusion and correction of class II cases

Displacement

springs

Bionater

•

Twin block

Frankel

Herbst Appliance ( a.k.a. the “shock absorber” or "Bite Jumper")

•correction of ant-post relationships of upper and lower jaws.

• encourages mandibular growth, eliminate extractions and surgical corrections with

headgears.

•The appliance is formed from a rod and tube (called the “shock absorber”) and actually

connects the upper and lower jaws.

• fully intraoraly and doesn’t interfere with function.

Herbst facts • Fixed to teeth

• Patient compliance not required

• Works 24 hours

• Less airway blockage

• Most popular type at present time in U.S.

Arms guide the lower jaw

forward to the ideal jaw

position

Upper Molars : Distalization

/Intrusion / Expansion

Upper Incisors : Retrusion /

Uprighting / Extrusion

Lower Molars : Mesialization /

Extrusion

Lower Incisors : Protrusion /

Intsusion

Reposition the Mandible

Jasper Jumper

MARA Appliance (mandibular anterior

repositioning appliance)

Correction of anteroposterior relationships of

upper and lower jaws.

Works by guiding the mandible forward with

occlusion.

Completely intraorally so

better compliance

and aesthetics.

Indications for the MARA

Ø The upper jaw is in good position and you

want to advance the mandible.

Ø It is desirable to inhibit maxillary anterior

growth and produce an increase in

mandibular length.

Ø You want to recapture a prolapsed disc.

Ø Adult cases, when lower jaw surgery is not

an option, needing a good compromise

Class II correction. While the result is

mostly dental, some mesial migration of the

fossa may occur.

THE END

Special thanks for

Assisst. Prof.

Amjad Al-Taki