Long-term stability of mandibular advancement with bilateral sagittal split osteotomy.

INTRODUCTION: Aim of this study was 1) to evaluate long-term dental/skeletal stability in patients with mandibular retrognathia corrected by BSSO, and 2) to examine factors associated with relapse. MATERIALS AND METHODS: Seventy-seven of initial 151 study cohort subjects who had undergone orthognathic surgery in 2007-2011 agreed to participate. Present paper presents data on dental/skeletal stability in 46 patients; 31 patients were excluded because of missing calibration indicator in one of the patients' pre-operative cephalometric radiographs, or because of pregnancy. Pre-operative (T1), post-operative (T2) and long-term follow-up (T3) radiographs and patient's files were used in the study. RESULTS: Based on overjet measurements, mean mandibular advancement was 5.7 mm and mean relapse 0.1 mm. Mean pre-operative overbite was 5.4 mm, reduction at surgery 3.4 mm and mean relapse 1.1 mm, a statistically significant change. Mean mandibular advancement measured from condyle tognathion (Co-Gn) was 6.5 mm. Relapse in Co-Gn was 1.6 mm on average, i.e., about 25% of the advancement. Amount of advancement, fixation method, patient's age or gender or orthodontist/surgeon experience did not have influence on relapse. CONCLUSIONS: Mandibular advancement with BSSO in healthy Class II patients is considered a stable procedure. 25% skeletal relapse was found with clinically non-significant dental changes.