The Effect Evaluation of Functional Appliance Used for Class II Patients With Temporomandibular Joint Anterior Disc Displacement

Abstract Orthopedic functional appliances are usually used to correct patients with retrognathic mandible. However, a part of cases have a trend of relapse after splint treatment. The aim of this study was to explore the role of temporomandibular joint disc position in functional appliance treatment. This study included 8 patients who had 1 joint anterior disc displacement with reduction (ADDWR) and the other joint anterior disc displacement without reduction (ADDWoR) confirmed by magnetic resonance imaging (MRI). Only the ADDWR joint could return to its normal position after wearing the anterior repositioning appliances (ARAs). Condylar morphology, condylar height, and disc length were evaluated 6 months after ARA treatment. The MRI showed that new bone appeared on 7 joints with ADDWR and on 1 joint with ADDWoR. The condylar height has increased 1.4 mm in the ADDWR group, while 0.1 mm shorter in the ADDWoR group. Disc length has increased from 8.5 to 8.7 mm in the ADDWR group and 0.4 mm shorter in the ADDWoR group after wearing the ARA. Our results suggested that it is noneffective of functional appliance used for class II malocclusion adolescents with ADDWoR and only a normal disc-condyle relationship benefits condyle growth by functional appliance. Thus it is important to reposition the disc as soon as possible.