Dental or skeletal relapse after sagittal split osteotomy advancement surgery? Long-term follow-up.

Purpose: To evaluate the short- and long-term stability of mandibular advancement surgery with sagittal split osteotomy (SSO), and to investigate when relapse occurs and identify variables contributing to relapse.

Patients And Methods: Thirty-six patients with Class II anomalies were included; the mean age at surgery was 33.0 years. All underwent SSO surgery and clinical and radiologic follow-up at 8 weeks, 1 year, and 13 years. Model analysis, cephalometric analysis, and clinical examinations were performed at each control.

Results: Mean overjet relapse from 8 weeks to 13 years was 2.3 mm (range, 0 to 7.0 mm). Between 8 weeks and 1 year, mean overjet relapse was 0.6 mm (range, -1.0 to 4.0 mm), and it was 1.7 mm (range, -1.0 to 6.0 mm) between 1 year and 13 years. Overjet relapse greater than 4 mm was found in 13.9% of the patients. Mean overjet 1 year after surgery was 2.6 mm and was significantly increased compared with 8 weeks (P = .006). Mean overjet 13 years after surgery was 4.3 mm and was significantly increased compared with 1 year (P < .001). Inferior incisor line to nasion-B-point was 29.0° at 8 weeks after surgery and 25.4° at 13 years (P = .001). Insignificant changes in the other cephalometric variables were found at follow-up.

Conclusion: SSO advancement surgery is a relatively stable technique over time. Mean overjet relapse was found to be 2.3 mm after 13 years, following a continuous pattern over time. The cephalometric variables showed insignificant changes during follow-up, indicating that relapses are mainly of dental and not skeletal origin.