FUNCTIONAL APPLIANCES

INTRODUCTION

• Originated and developed in Europe

• Controversy

• A group of orthodontic appliances

features

• Harness forces of muscles

• Construction bite

• Only work in growing children

• Can’t correct the teeth irregularity

Correction of Class malocclusionⅡCorrection of Class malocclusionⅡ

Categories of functional appliances

• Passive tooth-borne appliances: no active components

• Active tooth-borne appliances:including expansive screw or springs to move teeth

• Tissue-borne appliances: Functional Regulator-FR

Effects of functional appliances

Dento-alveolar changes

• Antero-posterior: Anterior movement of lower teeth, posterior movement of upper teeth.

• Vertical: lower posterior teeth erupt.

Modification of Maxillary growth

• Restrain the forward growth of maxilla

• Catch up growth occurs after treatment

Cephlomatric superimposition

Changes in mandibular growth

• Stimulate mandible growth

• Improve the growth direction of mandible

Cephlogram superimposition

Changes in glenoid fossae

• Remolding of the glenoid fossa more anteriorly

Indications for functional appliances

• The patient must still be growing,preferably approaching a phase of rapid growth.

• The pattern and direction of facial growth should be favorable.

• The profile improved immediately as the patient move mandible forward.

• The patient must be well motivated.• Dentition are well aligned

The timing of treatment

Late stage of mixed dentition,1-2 years before the pubertal growth occur

Female: 9~10 year old

Male: 11~12 year old

Management of functional appliances

Management of functional appliances

Diagnosis

• Skeletal or non-skeletal(dental)

• Mandibular retrusion or maxillary protrusion

• Degree of severity

Appliance Design

• No ideal appliance can be used in all situations

• Exactly what is desired in the treatment

• consideration of cost, complexity, acceptability

• Vertical control

• Mobile or exfoliating primary teeth

impression

• Differ with the diagnostic records

• Areas where appliance components will contact soft tissues must clearly delineated

• The impression must not stretch soft tissues in areas of contact with the appliance.

Bite registration

1.Anteroposterior dimension: for most patients: 4~6mm (edge to edge if no uncomfortable)

2.Vertical opening: 3~4mm in incisor region

Bite registration --methods

• A horseshoe-shaped wax bite rim is prepared

• Guiding the mandible into planned position

• Forming the wax bite

• Check and hardened

fabrication

Fit the appliance

• Instruction

• Check the surface of roughness, adjust clasps, capping

• How to insert and remove the appliances

• Initially few hours, gradually increase the wearing time. At least 14 hours each day over 2 weeks

First review appointment2 weeks later

Check and trim the appliance

Review appointment

• 1.Every 6~8 weeks

• 2.Check the appliance

• 3.Assess progress(improvement or no/slow improvement)

4.Adjustment

• Trimming of interocclusal elements to allow teeth erupt where desired

• Adjustment of the labial bow: reduce its contact with the anterior teeth

• Outward bending of buccal shields and lip pads,facilitate arch expansion

Retention

• Gradually reduce the amount of wearing time till sleeping hours only

• Period: the pubertal growth is over

Popular types of appliances

Activator

Tu

construction

• Base plane• Lip bow:transmit forces

to upper incisors• Lower incisors

capping: minimize ⑴the tendency of lower incisors procline

reducing overbite⑵

principles

Muscles stretched-producing forces-retracting mandible-transmitted to maxilla through labial bow-restraining the maxillary growth

Rules for construction bite

• In a forward positioning of the mandible of 7-8mm,the vertical opening must be slightly to moderated(2-4mm)

• If the forward positioning is no more than 3-5mm,the vertical opening should be 4-6mm

• The Activator can correct lower midline shift or deviation

Management

Checkup appointments should be scheduled every 6 weeks:

1.observing shiny surface to determine whether the appliance be worn correctly

2.trimming and reshaping acrylic guild areas

3.Acrylic contact guild plane often must be resealed.

4.The labial bows must be checked

5.In expansion treatment the jackscrew are normally activated by the patients at 1-week interval. Check the screw

Trimming

1.vertical control

• For dolichofacial patients:intrude molars, extrude incisors

• For branchfacial patients: intrude incisors, extrude molars

Acrylic contact Intrusion of the molars

Acrylic contour for extrusion of the molars

Intrusion of the incisors

2.sagittal control

Retrusion of the incisors

Mesial movement of molars

Distal movement of molars

3.transverse movement

bionator

principles

• Less buckly

• Adjust the function of tongue

• The working bite can’t be opened and must be positioned in an edge-to-edge relationship. If the overjet is too large,can be done step by step.

Types of Bionator

• Standard Bionator• Horseshoe-shaped

acrylic lingual plate• Palatal bar• Labial bow extend

buccally• No incisors capping

Open-bite Bionator

Class BionatorⅢ

Indications

• The dental are well aligned originally

• The mandible is in a posterior position

• The skeletal problem is not too severe

• A labial tipping of the upper incisors is evident

Clinical management

• The time interval between office visit is 3-5 weeks

• Adjust labial bow to touch the teeth lightly

• Trimming the interocclusal block to guild premolar into full occlusion

Frankel appliance(FunctionalRegulator-FR)

• The large part of Frankel appliance is confined to the oral vestibule

• The buccal shields and lip pads hold the buccal and labial soft tissue away from the teeth,eliminating restrictive influence

• The manner in which the anteroposterior correction is different

tu

variation

• FR1:correction of class division 1Ⅱ• FR2:correction of class division 1 and 2Ⅱ• FR3:correction of class Ⅲ• FR4:correction of openbite

• Among them, the FR2 and FR3 are often used

FR3

• Acrylic parts:• Lip pads:eliminate

restriction,stimulation of bone growth; transmitting forces to mandible

• Buccal shields: maxillary expansion

Steel wire

• Lower labial bow:restrain mandible

• Protrusion bow:stimulate forward movement of maxillary incisors

• Palatal bar: stabling component

• Occlusal rests:prevent lower molar erupt,open cross-overbite

Construction bite

• Retruding mandible as much as possible, generally edge to edge

• Vertical dimension: opened only enough to correct crossbite, allow wires to pass through, about 2mm in posterior region

Fabrication

Working model trimming

wax relief

wire forming

fabrication of acrylic portion.

Clinical management

• All margins are checked smoothness

• Fitting the appliance 1-2 weeks

• First visit: extending wearing time to 4-6 hours

• Second visit:exercises may be prescribed including speech and lip-seal

• Upper molars rest will be cut

Twin block appliance

tu

introduction

• Two pieces appliance

• Giving greater freedom of movement in anterior and lateral excursion

• The appliance can be worn full day

• Harness all oral functional forces especially the forces of mastication

• Correct the malocclusion rapidly

Construction bite

• Overjet≤10mm,bite may be activated edge to edge on incisors if the patient can posture forward comfortable

• Vertical dimension: 2mm interincisal clearance

Design and construction

Midline screw to expand the upper arch

Design and construction

retainer

Design and construction

Bite blocks

Design and construction

Inclined plane

Design and construction

Base plane

Design and construction

Labial bow

Stage of treatmentStage 1: active phase:twin block

Stage 2: support phase-anterior plane

Dolichofacial patients:non-trimming, prevent second molars extrusion

Branchfacial patients:trimming

Timing:1-2 months after the appliance was inserted

Method:trimming the upper block to leave 1mm clearance between bite and lower molar

Vertical control

trimming

Herbst

Removable appliances

• Producing tilting movements of individual teeth

• As an adjunct to fixed appliance treatment

• retention

Anterior bite plane

management

• The bite plane should be length enough to ensure the lower incisors bite on the bite plane.

• Add to the height of the bite-plane during treatment

Buccal capping

• Eliminating occlusion interference

• Dental incisors cross-bite

• Unilateral posterior teeth crossbite

Bilateral block

Unilateral block