"Comparative Evaluation of the Temporomandibular Joint Disc-condyle-fossa Relationship Following Functional Appliance Therapy in Skeletal Class II Division 2 Malocclusion in Adolescent Females : A Magnetic Resonance Imaging Study"

Angle's class II division 2 malocclusion is relatively rare. Its frequency lies between 1.5 and 5% of all occlusion in white western population while in north Indian population it is 5.8% Generally in Class II division 2 malocclusion mandibular denture is more distally placed in relation to maxillary denture, a compensating effect in this type of mandibular retrusion , which offsets some of the disharmony of the facial profile is that the chin point is usually very pronounced3. It has been stated that patients with skeletal class II division 2 malocclusion ,when compared with normal class I or class II division I subject have larger masticatory muscles that in addition are oriented in a more anterior direction. These characteristics results in significant differences regarding their mechanical advantage and magnitude of occlusal forces.5 Several investigators have also stated that the mandible is locked posteriorly in Angle's Class II division 2 malocclusion with deep bite and the treatment which unlocks the bite during an active growth period can allow the mandible to grow or be repositioned forward much more than if treatment of unlocking of a bite were not undertaken. In class II division 2 malocclusion the condyle is positioned posteriorly while the disk is positioned anteriorly in relation to glenoid fossa. The articular disc in Angle's class II Division 2 patients could take a relative protrusive position in comparison with the other Angle's classes of malocclusion .

Successful treatment of many orthodontic problems depends to a great extent on the amount of mandibular growth patients experience during treatment. Functional appliances have been used for nearly 100 years in an attempt to induce mandibular growth by changing muscle function and condyle glenoid fossa relationships. Several studies have shown that the treatment of skeletal Class II patients with functional appliances is more successful when initiated during the adolescent growth spurt.

MRI a multiplanar imaging technique, has the advantage of giving an accurate assessment of both the bony and the soft tissues.It has high sensitivity for visualization of position and configuration of disc . This technique is believed to be non-invasive, radiation free and gives more superior contrast resolution than any other imaging modality. Recent studies have shown that we can have greater confidence in MRI as diagnostic tool because of improved quality.

MATERIALS AND METHODS- It is a prospective descriptive study to evaluate TMJ disc-condyle-fossa relationship using MRI scan following functional appliance therapy in skeletal Class II Division 2 malocclusion in adolescent females.

The present study will be conducted in the Department of Orthodontics and Dentofacial Orthopedics, PGIDS, in association with the Department of Radiology, PGIMS, and Department of Oral Radiology, PGIDS, Pt B. D. Sharma University of Health Sciences, Rohtak.