MRI Changes in the Temporomandibular Joint after Mandibular Advancement

Purpose: Esthetic dental and skeletal component correction can affect the temporomandibular joint (TMJ). Arthrogenic TMJ dysfunction can be present in the joint at the outset or it can develop during the treatment or later. The aim of the present study was to examine the changes found on magnetic resonance imaging (MRI) studies of the TMJ in patients with skeletal Class II malocclusion who had undergone combined orthodontic and bilateral sagittal split ramus osteotomy (BSSRO) advancement. Our objective was to measure the changes in the disc position, condylar translation, secondary bony changes, and joint effusion on MRI before and after treatment. Materials and Methods: An analytical, single-surgeon, single-institution, retrospective radiological (MRI) study was designed. We included patients who had undergone combined orthodontic and BSSRO advancement from 2011 to 2018. All 36 patients were examined using a 1.5-Tesla MRI unit (Siemens Symphony, Erlangen, Germany) with a 6 x 8-cm diameter surface coil, which allowed for simultaneous imaging of both TMJs. Results: Analysis using the Wilcoxon signed rank test revealed statistically significant differences in the pre- and post-treatment groups in the changes in the position of the disc from anterior disc displacement with reduction (ADDWR) to the normal position (P = .008), condylar translation from excessive to normal (P = .046), and an increase in secondary bony changes (P = .005). Conclusions: Combined orthodontic and orthognathic movement in the treatment of skeletal Class II malocclusion can increase secondary bony changes, improve the disc position in ADDWR cases, and control excessive translation of the TMJ. No improvement was noted in the position of the disc in those with anterior disc displacement without reduction, hypomobility and joint effusion. (C) 2020 American Association of Oral and Maxillofacial Surgeons