The value of long-term follow-up of mandibular advancement surgery in patients with a low to normal mandibular plane angle

The objective of this study was to evaluate retrospectively the stability of mandibular advancement via bilateral sagittal split osteotomies. Two fixation methods were compared: intermaxillary fixation (IMF) and rigid internal fixation (RIF). The hypothesis was that, in patients with a low to normal mandibular plane angle (MPA) in retrognathia, the bilateral sagittal split osteotomy (BSSO) to advance the mandible is a predictable and stable procedure and that no significant changes occur after 1 year. Twelve patients with mandibular deficiency with a low to normal MPA (mean 24.7°, range 20.3°–30.7°) underwent BSSO with IMF. The follow-up period was at least 5 years (mean 6.3, range 5–9.1 years). Cephalometric analysis using a commercial software package was performed on radiographs that were taken immediately preoperatively (TO), within 6 weeks postoperatively (T1), 1 year post-operatively (T2), and at least 5 years postoperatively (T3). The average advancement at B point was 4.7 mm (range: 3–7 mm). The assessment of B point in regard to relapse showed no significant change. One patient showed a relapse due to condylar resorption. Forty-five consecutive patients were treated with RIF. Radiographs were taken preoperatively (T0), 6 weeks post-operatively (T1), and 1 year post-operatively (T2). This group had a mean MPA of 26.2°, range 10°–32°. The average B-point advancement was 4.4 mm (range 1–10 mm). No patient showed a clinically significant relapse at T2.