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Myofunctional appliances

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Are appliances that utilize natural forces of orofacial and masticatory musculature for their action

Functional appliances are conceptually based on Moss’ functional matrix theory

Functional matrix theory proposes that functional matrices, tissues like muscles and glands influence skeletal units such as jaw bones and ultimately control their growth

Classifications of functional appliances:

1.removable functional appliance A)removable tooth borne applianceB)removable tissue borne appliance

2. fixed functional appliance

Functional appliance types Orthodontic functional appliances may

be active or passive: Active appliances reposition the mandible

so that the condyle is forced out of the glenoid fossa and this in turn is thought to stimulate the posterior/superior growth of the condyle

Passive appliances act by repositioning the musculature associated with the mandible so that the jaw bone itself responds by growing to the new equilibrium position

Passive functional appliances Frankel

Active functional appliances Fixed active functional appliances

Herbst

Active functional appliances Removable active functional

appliances Bionator

Active functional appliances Removable active functional

appliances Woodside activator

Active functional appliances Removable active functional

appliances Twin-block appliance

Mode of action

Most of funtional appliances act by utilizing one or more the following

1.a forced mand. Posture which transmites forces to the teeth and jwas.

2.bite planes which produce deffrential eruption

Advantage of functional appliances

1.functional appliances are effective in vertical controll of increased over bite

2.can be used in mixed dention

3.minimal chiar side adjusment

Disadvantage

1.succes of functional appliances depend on patient cooperation.

2.there is no precise tooth movement

3.treatment duration is often prolonged.

4.need to faces treatment to complete treatment

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

These appliances should be worn at nighttime as this is when growth takes place

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)

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

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

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.

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.

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

Refernces

http://cache.virtualtourist.com/3709891-Long_neck_Karen_in_Shan_state_of_Burma-Burma.jpg

http://farm1.static.flickr.com/47/154578698_6011a485ce.jpg

http://www.sleepingtiger.org/blog/wp-content/uploads/2007/08/maxyawns.jpg

http://imagecache2.allposters.com/images/146/PP0195.jpg http://www.nimrodental.co.uk/appliances/media/

functional5.jpg http://coloradospringsortho.com/Web%20site/About

%20braces_files/herbst_appliance.jpg http://www.weisskircher.de/bilder/bionator.jpg http://www.tanos.co.uk/braces/bkb/images/

activatorwoodside.jpg http://www.orthodentlab.com/products/images/photos/

TwinBlock1.jpg

References

Harrison JE, O’Brien KD, Worthington HV. Orthodontic treatment for prominent upper front teeth in children (review). The Cochrane Collaboration. John Wiley & Sons, 2008.

Nguyen QV, Bezemer PD, Habets L, Prahl-Andersen B. A systematic review of the relationship between overjet size and traumatic dental injuries. European Journal of Orthodontics 1999;21(5):503-515.

Pavlow SS, McGorray SP, Taylor MG, Dolce C, King GJ, Wheeler TT. Effect of early treatment on stability of occlusion in patients with Class II malocclusion. American Journal of Orthodontics and Dentofacial Orthopedics 2008;133:235-244.

Dolce C, McGorray SP, Brazeau L, King GJ, Wheeler TT. American Journal of Orthodontics and Dentofacial Orthopedics 2007;132:481-489.

Cozza P, Baccetti T, Franchi L, De Toffol L, McNamara JA. Mandibular changes produced by functional appliances in Class II malocclusion: a systematic review. American Journal of Orthodontics and Dentofacial Orthopedics 2006;129:599.e1-599.e12.