Outcome of surgical-orthodontic treatment in hemifacial microsomia with and without early mandibular distraction osteogenesis.

The aim of this study was to compare the outcomes of surgical-orthodontic treatment between hemifacial microsomia (HFM) patients who had and had not undergone early mandibular distraction osteogenesis (DO). Twenty adult unilateral HFM patients were included, seven who had undergone early mandibular DO (DO group) and 13 who had not (NDO group). All patients were type IIB, except for one type IIA patient in the NDO group. Mean age at definitive surgery was 20.72±2.96 years. Linear, cross-sectional, and volumetric measurements were obtained from serial cone beam computed tomography scans. Data were obtained pre-surgery (T0), 1 week after surgery (T1), and at treatment completion (T2) to determine surgical movement, post-surgical stability, and net gain movement. Surgical and ultimate outcomes did not differ significantly between the groups. The overall surgical movement among all patients was as follows (mean values): maxillomandibular complex (MMC) symmetry was achieved by Le Fort I differential roll movement (3.78mm extrusion on the affected side, 4.28mm impaction on the non-affected side), a combination of medial movement and yaw rotation of MMC, and genioplasty. Upper and lower dental midlines and deviated menton were shifted by 5.73mm, 5.08mm, and 12.38mm, respectively. Anterior impaction and advancement with counterclockwise rotation of MMC were also performed. Menton was advanced by 6.14mm and lower facial height was increased by 3.55mm. Neither group exhibited a significant difference in stability. Relapse at the maxilla was <1mm and relapse at the mandible was <1.5mm. The results suggest that early DO had limited beneficial effects on the definitive correction outcome. HFM patients achieved acceptable symmetry and a stable surgical outcome, regardless of early DO, following surgical-orthodontic correction at skeletal maturity with three-dimensional surgical simulation.