Journal of AdvancedMedical and Dental Sciences Research

Introduction: The utilization of orthopedic functional appliances to correct Class II malocclusions seen in the retrognathic mandibles is suggested in the first stage of orthodontic treatment. A second stage of treatment is done by fixed orthodontic appliances for the occlusal refinement. Hence in the present study we evaluated clinically and by MRI, the changes in the position and form of the temporomandibular joint articular disc after orthodontic appliance. Materials and Methods: Forty teenagers with each twenty boys and girls with Angle Class II division 1 malocclusion and mandibular retrognathism were selected. First Herbst appliance was given for an year, followed by the fixed orthodontic appliance. The TMJs were evaluated qualitatively by means of magnetic resonance images at the beginning of treatment (T1), during stage I (T2), at the end of stage I (T3), and at the end of stage II (T4). Results: Significant changes in disc position were not observed with the mouth closed between T1 x T3 (P =.3170), T3 x T4 (P = .2817), or T1 x T4 (P = .2611). At T2, on average, the disc was positioned regressively. With the mouth open, no difference was observed between T1 x T3 (P = .2213) or T1 x T4 (P = .0802). We did observe a significant difference between T3 x T4 (P < .05). Significant changes in the disc form were found with the mouth closed between T1 x T2 (P < .001) and T2 x T3 (P < .001). Conclusion: At the end of the two-phase treatment, in general terms, the position and form of the initial articular discs were maintained; however, in some temporomandibular joints some seemingly adverse effects were observed at T4. Key words: Temporomandibular joint; Magnetic resonance; Angle Class II malocclusion.