Postoperative stability after setback of sagittal split ramus osteotomy: a comparison of three techniques

The aim of the present study was to evaluate the postoperative stability after bilateral sagittal split ramus osteotomy (BSSRO) for the treatment of mandibular prognathism, in addition to a posterior ostectomy of the distal segment and mandibular angle resection.

The present retrospective study included patients with mandibular prognathism who were treated with BSSRO at Kangdong Sacred Heart Hospital from July 2007 to July 2011. We assessed the linear changes in the chin position in 17 patients with BSSRO only (control group), 10 with BSSRO and posterior ostectomy of the distal segment (experimental group 1), and 13 with BSSRO and mandibular angle resection (experimental group 2). A cephalogram was taken 2 weeks before surgery and 1 day and 2 months postoperatively. Differences among the groups were determined using 1-way analysis of variance.

The demographic and surgical variables were similar among the groups. With regard to the changes observed 1 day to 2 months postoperatively, no statistically significant differences were found; however, the proportion of patients who had highly significant changes (>4 mm) was different. Point B moved forward and upward more than 4 mm in approximately 18% and 12% of patients, respectively, in the control group. However, such movement was not observed in any patient in the experimental group.

Less postoperative instability was present in the experimental groups than in the control group. This might have resulted from the reduced tension in the pterygomasseteric sling and the minimized interference between the bony segments. Therefore, improved stability can be obtained regardless of the type of additional procedures.