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

Abstract

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 degrees, range 20.3 degrees-30.7 degrees) 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 (T0), within 6 weeks postoperatively (T1), 1 year postoperatively (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 postoperatively (T1), and 1 year postoperatively (T2). This group had a mean MPA of 26.2 degrees, range 10 degrees-32 degrees. The average B-point advancement was 4.4 mm (range 1-10 mm). No patient showed a clinically significant relapse at T2.