Skeletal and dental stability of segmental distraction of the anterior mandibular alveolar process. A 5.5-year follow-up.

17 patients (14 female; 3 male) were analysed retrospectively for skeletal and dental relapse before distraction osteogenesis (DO) of the mandibular anterior alveolar process at T1 (17.0 days), after DO at T2 (mean 6.5 days), at T3 (mean 24.4 days), at T4 (mean 2.0 years), and at T5 (mean 5.5 years). Lateral cephalograms were traced by hand, digitized, superimposed, and evaluated. Skeletal correction (T5-T1) was mainly achieved through the distraction of the anterior alveolar segment in a rotational manner where the incisors were more proclined. The horizontal backward relapse (T5-T3) measured -0.3mm or 8.3% at point B (non-significant) and -1.8mm or 29.0% at incision inferior (p<0.01). Age, gender, amount and type (rotational vs. translational) of advancement were not correlated with the amount of relapse. High angle patients (NL/ML'; p<0.01) showed significant smaller relapse rates at point B. Overcorrection of the overjet achieved by the distraction could be a reason for dental relapse. Considering the amount of long-term skeletal relapse the DO could be an alternative to bilateral sagittal split osteotomy for mandibular advancement in selected cases.