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 Ⅱmalocclusion

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

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 appointment 2 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:⑴minimize the tendency of lower incisors procline ⑵reducing overbite

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 contour for extrusion of the molars Acrylic contact Intrusion of the molars

Intrusion of the incisors

2.sagittal control Retrusion of the incisors

Distal movement of molars Mesial 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 Ⅲ Bionator

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(Functional Regulator-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 Ⅱdivision 1 FR2:correction of class Ⅱdivision 1 and 2 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 1: active phase:twin block Stage of treatment Stage 1: active phase:twin block

Stage 2: support phase-anterior plane

Vertical control 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

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