Long-term prognosis of BSSO mandibular relapse and its relation to different facial types.

The bilateral sagittal split osteotomy (BSSO) has evolved into an effective and preferred surgical procedure for mandibular setbacks. As with all surgical procedures designed to setback the mandible, relapse occasionally occurs after BSSO procedures. Several factors have been suggested to play a contributory role in this relapse. The present study was performed to determine the stability of the mandibular position over the course of long-term observation. Different facial patterns that could potentially be used as predictors of relapse were examined. The study included cases of skeletal mandibular prognathism, with the patient in each case having undergone surgical correction involving a BSSO at least 5 years prior to the study. Lateral cephalograms were analyzed in order to classify facial patterns. Angular and linear cephalometric measurements, consisting of SN-Pogonion angle, SN-occlusal plane angle, and Pogonion depth and height, were compared at 1 year postoperatively and at the long-term follow-up. A significant correlation between facial type and relapse pattern was confirmed at the long-term assessment of prognosis.