Three-dimensional analysis of condylar remodeling and skeletal relapse following bimaxillary surgery: A 2-year follow-up study

Purpose: To quantify the postoperative condylar remodelling and its role in skeletal relapse after bimaxillary surgery.

Materials and methods: 50 patients with mandibular hypoplasia who underwent bimaxillary surgery were analyzed. CBCT scans were acquired preoperatively, one week postoperatively and two years postoperatively. 3D cephalometric analysis was carried out for each CBCT scan, after which the condylar volume analysis was performed.

Results: The maxilla was advanced by a mean of 2.1 mm with a corresponding mean relapse of 0.3 mm. The maxilla was impacted in 23 and extruded in 27 patients. The mean mandibular advancement was 7.8 mm. Two years after surgery a mean mandibular skeletal relapse of 1.3 mm was observed. 78% of condyles exhibited a postoperative reduction in volume of 179 mm³ (mean), equivalent to 12.5 volume%. Postoperative condylar volume loss was correlated with mandibular skeletal relapse (r = 0.42, p < 0.01), but not with maxilla relapse. Linear regression analysis identified age, gender, amount of surgical mandibular advancement and postoperative condylar volume loss as predictive factors for mandibular relapse.

Conclusion: A significant correlation between postoperative condylar volume loss and skeletal relapse was found. Young female patients who underwent large bimaxillary advancement and postoperative reduction in condylar volume were particularly at risk for skeletal relapse.