偏位顎突出症患者における下顎枝傾斜の自発的変化とその顆頭および関節腔への影響：3次元比較解析

The aim of this study was to analyse the spontaneous changes in ramal inclination following mandibular setback surgery in patients with asymmetric prognathism. The stability of these changes and their impact on the condylar head position and joint space were evaluated. Fifty-three condyles were included and categorized into deviated side (D) and non-deviated side (ND) groups. Data were collected from cone beam computed tomography scans obtained preoperatively (Pre), immediately postoperative (Post), and at 6 months postoperative (6 m). The raw files were analysed using 3D software. On the deviated side, the condylar heads shifted significantly laterally and rotated inward (yaw) during surgery. On the non-deviated side, they shifted inferiorly and rotated outward (roll). These intraoperative rotations (ramal yaw, ramal roll) were maintained throughout the remodelling period (P = 0.001 and P = 0.006, respectively). Spontaneous rotation of the ramus helped resolve the imbalance in ramal inclination between the deviated and non-deviated sides. It did not significantly affect condylar head volume or joint space (Pre-6 m, P > 0.05). These findings suggest that intentional adjustment of the ramal inclination may be a feasible approach to compensate for imbalances in yawing and rolling in patients with deviated mandibular prognathism.