Three-dimensional virtual-surgery simulation-assisted asymmetric bilateral mandibular distraction osteogenesis for a patient with bilateral condylar fractures

Abstract

Introduction: Our objective was to report a patient treated with 3-dimensional virtual-surgery simulation-assisted asymmetric bilateral mandibular distraction osteogenesis. Methods: A boy (age, 9.5 years) had mandibular hypoplasia and facial asymmetry, induced by bilateral condylar fractures at 4 years of age. The asymmetric bilateral mandibular distraction osteogenesis was planned to correct facial asymmetry and mandibular hypoplasia. The 3-dimensional virtual-surgery simulation results were 11 mm of horizontal distraction on the right side and 4.5 mm of horizontal and 18 mm of vertical distraction on the left side of the mandible. Bilateral ramus osteotomies were performed, and intraoral unidirectional distraction devices were inserted. After a 6-day latency period, distraction was performed at 1 mm per day, followed by a 5-month consolidation period. Transarch and interarch elastics and an acrylic plate were used during distraction and consolidation. Total treatment time was 30 months. Results: Satisfactory outcomes were obtained (achievement ratios between postconsolidation results and simulated results: gonial angle, 106% and 103.9%; mandibular body length, 94.2% and 89.9%; ramus height, 104.1% and 94.5% [values of the right and left sides, respectively]). The chin-point deviation and the transverse cant of the maxillary occlusal plane were significantly improved (10.1 mm to 3.3 mm; -6.8 degrees to -4.4 degrees). At 53 months of follow-up, the Class I molar relationship was well maintained. The transverse cant of the maxillary occlusal plane was slightly improved to -3.7 degrees during pubertal growth. Conclusions: Three-dimensional virtual-surgery simulation can help clinicians to determine the optimal vector and amount of distraction with high accuracy in complex cases requiring simultaneous correction of a hypoplastic mandible and facial asymmetry.