Effect of bilateral sagittal split ramus osteotomy on temporomandibular joint symptom and condylar position in patients with skeletal class III malocclusion by cone beam computed tomography

OBJECTIVE To investigate the effect of bilateral sagittal split ramus osteotomy (BSSRO) on temporomandibular joint (TMJ) symptom and condylar position in patients with skeletal class Ⅲ malocclusion treated with orthodontic-orthognathic surgical treatment. METHODS Twenty-four patients with skeletal class Ⅲ malocclusion who underwent orthodontic-orthognathic surgical treatment were included in the study. Their cone-beam computed tomography scans and TMJ symptom were evaluated, and their Helkimo index before BSSRO, 1 month after BSSRO, and 12 months after BSSRO was recorded. The maximum diameter of the horizontal and coronal sections, short axis diameters, neck width, height, joint space widths at different angles (45°, 90°, and 135°) of the condylar joint, bilateral condylar spacing, and different condylar angles (horizontal angle, vertical angle, and stress angle) in three dimensions were measured. Then, the changes in TMJ symptom and bone structure at different periods were analyzed. RESULTS The Helkimo index was anamnestic (Ai) or dysfunctional (Di) levels 0 or 1 before and after BSSRO, and no difference in Helkimo index was observed. The horizontal angle and joint space widths at 45° and 90° increased whereas the joint space width at 135° decreased at 1 month after BSSRO compared with before BSSRO (P 0.05) 12 month after BSSRO. CONCLUSIONS BSSRO would not have a remarkable effect on the TMJ symptom and condylar position of patients with skeletal class Ⅲ malocclusion who underwent orthodontic-orthognathic surgical treatment procedure and whose Helkimo index ranked Ai0, Ai1, Di0, and Di1.