Correlation between condylar repositioning, resorption, and mandibular relapse post-orthognathic surgery with the straight locking miniplate technique in patients with Class II and III malocclusion: a retrospective study.

This study investigated the relationship between condylar position, condylar volume, and mandibular relapse following orthognathic surgery in which the proximal segments were temporarily fixed with a positioning device to maintain the condylar position. Computed tomography data (pre-surgery, immediately post-surgery, and 1 year post-surgery) from 12 patients with Class II malocclusion and 20 with Class III were analysed. Condylar volume was significantly lower in Class II patients than in Class III patients at all time-points (P < 0.001), and only Class II patients showed a significant volume reduction from immediately post-surgery to 1 year post-surgery (P < 0.001). Three-dimensional condylar movements from pre-surgery to immediately post-surgery and from pre-surgery to 1 year post-surgery were significantly greater in Class II patients than in Class III patients (both P < 0.001). Additionally, Class II patients exhibited more restoration movements to the preoperative position from immediately post-surgery to 1 year post-surgery, correlating with the volume reduction (r = -0.53, P = 0.007), which in turn correlated significantly with mandibular relapse (r = 0.63, P < 0.001). These findings suggest an association between preoperative volume, intraoperative movement, condyle movement restoration, volume reduction, and postoperative mandibular relapse, particularly in the Class II group. Accurate condylar positioning appears crucial for mitigating mandibular relapse in Class II cases.