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Functional Orthodontic Appliances Dr. Omar.S.M.J.Ali PhD. Orthodontic

Conventional orthodontic appliances use mechanical force to alter the position of tooth/ teeth into a more favorable position. However, the scope of these fixed appliances is greatly limited by certain morphological conditions which are caused due to alteration in the developmental process or the neuromuscular capsule surrounding the orofacial skeleton. To over come this limitation, functional appliances came into being.

These appliances are considered to be primarily orthopedic tools to influence the facial skeleton of the growing child. The uniqueness of these appliances lies in the fact that instead of applying active forces, they transmit, eliminate and guide the natural forces (e.g. muscle activity, growth, tooth eruption) to eliminate the morphological aberrations and try to create conditions for the harmonious development of the stomatognathic system . Most of the functional appliances are intraoral devices, and nearly all of them are tooth borne or supported by teeth.

With a few exceptions, these appliances are removable, consisting primarily of acrylic with wire components for retention and support. Most of the functional appliances are used to correct early Class II malocclusions and some cases of Class III malocclusion. About 40 %of all malocclusions treated belong to the Class II category


CLASSIFICATION OF FUNCTIONAL APPLIANCES Myofunctional appliances are classified into: I. Classification put (Tom Graber) when functional appliances were removable: Group A-Teeth supported appliances, e.g. catlans appliance. 2. Group B-Teeth/tissue supported, e.g. activator, bionator, etc. 3. Group C-Vestibular positioned appliances with isolated support from tooth/tissue, e.g. Frankel appliance, lip bumpers.


II. With advent of fixed functional appliances, a new classification evolved: 1. Removable functionals, e.g. activator, bionator, frankel, etc. 2. Semi-fixed functional appliances, e.g. Den Holtz, Bass appliances, etc. 3. Fixed functional appliances, e.g. Herbst, Jasper jumper,

Classification (Profitt)

1. Teeth borne passive appliances-myotonic appliances, e.g. activator, 2. Tooth borne active appliances myodynamic appliances, e.g. elastic open activator (EOA) etc. 3. Tissue borne passive appliance, e.g. oral screen, lip bumpers, etc. 4. Tissue borne active appliances, e.g. Frankel appliances. 5. Functional orthopedic magnetic appliances (FOMA)

Timing of Treatment Effective during active growth effective growth The faster the growth, the faster the response, the shorter the treatment time. Most common time for treatment growth spurt. Early treatment- 9-10 yrs. Definitive treatment- 12-13yrs.

Early Treatment

To intercept a developing problem to Improve aesthetics Decreased trauma risk to anterior teeth Early correction of habit Improve eventual prognosis Decrease length of definitive Treatment

Definitive Treatment

During growth usually all permanent teeth have erupted. Correction max-mand discrepancy. Usually followed by fixed appliance Treatment Functional appliance may also be used during fixed appliance treatment

Effects of Treatment

Skeletal Condylar growth Increased condylar remodel Increased glenoid fossa remodeling Increased lower face height Dental Retroclination of upper incisors Proclination of lower incisors Mesial eruption of lower posterior teeth

Mode of Action of Functional Appliances 

Dentoalveolar changes Restriction of forward growth of maxilla Stimulation of mandibular growth beyond growth what is normally seen in growing children Redirection of condylar growth from upward growth and forward directed growth to posterior direction

Changes in neuromuscular anatomy and function that would induce bone remodelling Adaptive changes to glenoid fossa location to a more anterior and vertical location direction

Dento-Alveolar Effects

Dento-alveolar changes 60 -70%. Inhibition of downward and forward eruption of maxillary teeth. Retroclination upper incisors. Proclination of lower incisors.

Orthopaedic Effects

Orthopaedic changes 30-40% Condylar growth Increased condylar remodelling Increased glenoid fossa remodelling Increased lower facial height

INDICATIONS

Actively growing individual with favorable growth pattern are good for the activator therapy.Various types of activators have been devised for the treatment of various conditions like:• Class II division 1 malocclusion• Class II division 2 malocclusion• Class III malocclusion• Class I open bite malocclusion• Class I deep bite malocclusion• For post-treatment retention• Children with decreased facial height

CONTRAINDICATIONS

Cannot be used in correction of Class I problems of crowded teeth where there is disharmony between tooth size and jaw size cannot be used in children with excess lower facial height. Cannot be given in cases with lower proclination In case of nasal stenosis. In non-growing individuals.

ADVANTAGES

1-Uses existing growth 2- Minimal oral hygiene problems 3-Appointments usually short

DISADVANTAGES

• Requires good patient co-operation• Cannot produce precise detailing and finishing of the appliance

PHILOSOPHY OF ACTIVATOR

Various views have been put forward to explain the mode of action of the activator. Some implicate the reflex myotactic . Activity and isometric contractions while others attribute the results to the viscoelastic properties and stretching of the muscles and soft tissues. However the basic fact remains that most of the changes are induced by holding the mandible forward and the ensuing reaction of the stretched muscles and soft tissues, transmitted to the periosteum, bones and the teeth. A restraining effect on the growth of the maxilla and the maxillary dentoalveolar complex is also seen along with the stimulation of mandibular growth and mandibular alveolar adaptation. Research has also shown favorable changes in the TMJ region.

COMPONENTS OF THE ACTIVATOR

It consists of the following elements: 1. Labial bow The wire used is spring hardened 0.9 mm S.S.. The primary wire element of the activator consists of an upper and/or lower labial bow. It consist of horizontal middle sections, two vertical loops and wire extensions through the canine-deciduous first molar embrasure into the acrylic body.


2. Jack screw :optional (fitted to maxillary arch). 3. Acrylic portion :This can be fabricated in cold cure acrylic directly on the models or a wax matrix can be made first and then invested in the flask.

Fabrication

Impressions Impressions of upper and lower arches are made to construct 2 pairs of models - study models, working models

Bite Registration

-Amount of sagittal and vertical advancement is planned -Horse-shoe shaped wax block is prepared. -It should be 2-3 mm more than the vertical opening planned, patient is asked to practice placement of mandible at the desired position

Articulation of the Model

Preparation of Wire Elements
A labial bow is prepared with 0.8 or 0.9 mm wire. The ends of the wire enter the acrylic body. The labial bow can be active or passive. Depend on What?????

Fabrication of Acrylic Portions

Appliance consists of three parts• Maxillary part• Mandibular part• lnterocclusal partThe maxillary and mandibular parts are same asthe acrylic portions of upper and lower Hawley's plate,but these are joined by an interocclusal part which makes this appliance into a single block. The inter occlusal portion has the indentations of upper and lower teeth and caps the lower anterior, which controls their supra-eruption and proclination.

MANAGEMENT OF THE APPLIANCE

---The patient is demonstrated to place and remove the appliance in mouth. The appliance is to be worn 2 to 3 hours during the day for the first week. ---During the second week the patient sleeps with the appliance in mouth and wears it for 14 hours each day. ---The appliance is checked during the third week to evaluate the trimming. --- If the patient is wearing the appliance without any difficulty and following the instructions, checkup appointments are scheduled every 6 weeks.


BIONATOR

PHILOSOPHY OF BIONATOR

According to Balters, "the equilibrium between the tongue and the circumoral muscles is responsible for the shape of the dental arches and that the functional space for the tongue is essential for the normal development of the orofacial system" e.g. posterior displacement of the tongue could cause Class II malocclusion. Taking into consideration the dominant role of the tongue, Balters designed an appliance, which could take advantage of tongue posture. Thus he constructed an appliance whereby the mandible was positioned anteriorly, with the incisors in an edge to edge position. This forward positioning brought the dorsum of the tongue in contact with the soft palate and helped accomplish lip closure. Thus the principle of bionator is not to activate the muscles but to modulate muscle activity, thereby enhancing the normal development of the inherent growth pattern and eliminate abnormal and potentially deforming environmental factors.

Mechanism of action of Bionator

The bionator modulates the activity of the muscle thereby : 1.Enhances normal development of inherent growth pattern; 2.Eliminating abnormal and potentially deforming environmental factor

Indications For Bionator Therapy

In actively growing children for the management of class II division I or class II division2; In class I malocclusion with deep bite Class II division I malocclusion in the mixed dentition is indicated only under the following conditions.

1.The dental arches are well aligned originally. 2.The mandible is in functional retrusion. 3.The skeletal discrepancy is not to severe.

CONTRAINDICATIONS

• Class II relationship caused by maxillary prognathism• Vertical growth pattern• Labially tipped lower incisors • Children with neuromuscular diseases

BIONATOR TYPES

Three basic constructions are common in bionator• Standard appliance• Open-bite appliance• Class III or reverse bionator

Standard Bionator

Uses: 1.In the treatment of class II division I malocclusion in order to correct the backward position of the tongue and its consequences. 2.For the treatment of narrow dental arches of class I malocclusion


Components parts 1.Labial bow 2.Palatal bar 3.Construction bite or acrylic portion

Function of labial bow

1.To guide the posture and function of the lips and cheeks. 2.The posterior portion of the labial bow are designed as buccinators loops , they keep the soft tissue away of the cheeks which is normally drawn into the interocclusal. They actually move the surface of the oro buccal capsule laterally ,.this removal of inhibitory influence of expansion or transverse development of the maxillary dentition.

Open Bite Appliance

This is used to inhibit abnormal posture and function of the tongue. The construction bite is kept as low as possible with acrylic bite blocks between the posterior teeth to prevent their extrusion. The acrylic portion of the lower lingual part extends onto /up to the upper incisor region as lingual shield, to prevent tongue movements. The palatal bar has the same configuration. The labial bow is quite similar with the exception that the wire runs approximately between the incisal edges

Function of labial wire

1.It is placed at the height of correct lip closure to stimulate the lip to achieve a competent seal and relationship 2.Vertical strain on the lips tend to encourage the extrusive movements of the incisors which facilitates closure of the open bite after eliminating the adverse tongue pressures

Class III or Reverse Bionator

The labial bow runs in front of the lower incisors. It prevents labial tipping of the lower incisors

ADVANTAGES OF BIONATOR

Appliance is less bulky. 2. Can be worn full time, except during meals. 3. Appliance exerts a constant influence on the tongue and oral muscles.


DISADVANTAGE OF APPLIANCE
The main disadvantage is the difficulty of correctly managing it.

Frankel Function Appliance

Function regulator appliances were developed by Rolf Frankel (Germany). Frankel believed that the active muscle and tissue mass i.e., the buccinator mechanism and the orbicularis oris complex have a major role in the development of skeletal and dentofacial deformities. Hence he developed function regulators as orthopedic exercise devices, to aid in the maturation, training and reprogramming of the orofacial neuromuscular system.

FRANKEL PHILOSOPHY

1. Vestibular area of operation - Shields of the appliance extend to the vestibular and this prevents the abnormal muscle function. 2. Sagittal correction via tooth borne maxillary anchorage - Appliance is fixed on the upper arch by grooves mesial to the 1st permanent molar and distal to the canine in the mixed dentition period. - Presence of the lingual pad acts as stimulor and helps in the forward posturing of the mandible.

3. Differential eruption guidance - Frankel is placed on the upper teeth. - Mandibular posterior teeth are free to erupt and their unrestricted upward and forward movement contributes to both vertical as well as horizontal correction of the malocclusion. 4. Periosteal pull by buccal shields and lip pad - Presence of buccal shields and lip pads exert the periosteal pull which helps in bone formation and lateral expansion of the maxillary apical base. 5. Minimal maxillary basal effect - Downward and forward growth of maxilla seems to be restricted, even though lateral Maxillary expansion in seen.

MODE OF ACTION OF FR

1. Increase in transverse sagittal direction - by use of buccal shields and lip pads 2. Increase in vertical direction - by allowing the lower molar to erupt freely because appliance is fixed to the upper arch 3. Muscle adaptation - The form and extension of the buccal shields and lip pads along with the prescribed exercises corrects the abnormal peri-oral muscle activity.

Types of FR

1. FR I-used for Class I and Class II, Division 1. FR -Ia -used for Class I, moderate crowding and deep bite. FRlb-used for Class II Division 1 overjet less than 7mm. FRlc-used for Class II Division 1 overjet more than 7mm. 2. FR II-used for Class II Division 2 and Division 1 3. FR III-used for Class III 4. FR IV-used for cases with open bite and bimaxillary protrusion. 5. FR V-FR with headgear

TREATMENT TIMING

The best therapeutic effect of the Frankel appliance is achieved during the late mixed and transitional dentition period, when both the soft and hard tissues are undergoing their greatest transitional changes. Treatment for Class III and open bite cases should usually start soon as possible than for Class II problems.


FRIa
Not popular. Replaced by FRIb - Used for Class I moderate crowding and deep bite - Lingual wire loops are given instead of acrylic lingual pads to posture the mandible forwards - The cross over wire (passing between upper and lower occlusal surface) is an extension of the lingual loops.

FRlc

Used in Class II Division I with over jet greater than 7 mm. - It has been observed that posturing the mandible forward into a Class I relationship and eliminating excessive overjet in one step for a Frankel appliance is neither feasible nor necessary. Because tissue response is less favorable and there is increased patient discomfort or compliance. - So mandibular protraction is done in 2 or 3 steps. - Horizontal and vertical cuts are made on the buccal shield and then made to slide along the hanger - The cuts are then filled with cold cure acrylic

FR II

Used for Class II Division 2 and Division 1- Protrusion bow is made unlike in FRI- Canine loops• It is only a recurved loop• It originates in the buccal shield and contactsthe buccal surface of the canine as a recurved loop.• It shields the canine against the buccinator action.• It is placed 2-3 mm away from the deciduous canines

FR III

- Used for Class III correction - Lip pads are in the maxillary arch - Labial bow resting against mandibular teeth. Protrusion bow is on the upper teeth and is made of 0.8 mm wire for forward movement of maxillary incisiors if desired. - The occlusal rest is on the mandibular molar unlike in FRII where it is on the maxillary molar

FRIV

- Used for open bite and bimaxillary protrusion - Has no canine loops - Has no protrusion bow - Four occlusal rests present i.e, on deciduous 1st molar and permanent 1st molar on each side to prevent eruption of posterior teeth. - Palatal bar resembles FR III i.e. it does not contact the teeth - The buccal shield in FR IV should be wafer thin to enable lip closure and exercise without which the appliance will be a failure.

Frankel appliance used along with head gear

MYOBRACE

The Myobrace treatment goals for best results are

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