Mandibular distraction osteogenesis using an intraoral device and bite plate for a case of hemifacial microsomia.

OBJECTIVE: To present orthodontic treatment combined with mandibular distraction osteogenesis using an intraoral device and a bite plate in a patient with hemifacial microsomia, severe facial asymmetry, and unilateral mandibular hypoplasia. PATIENT: An 8-year-old girl exhibited mandibular deviation resulting from hypoplasia of the mandibular condyle and ramus on the left side. The patient was treated with an intraoral device for mandibular distraction osteogenesis, bite plate, and hybrid-type functional appliance. Facial asymmetry was improved, and the mandibular ramus was elongated in an anterior and primarily posterior direction with slightly posterior and superior displacement of the proximal segment. Postdistraction treatment results have been stable for 1 year. At the 1-year follow-up, the volume of the lateral and medial pterygoid muscles on the left side had increased. The condyle and disc on the right temporomandibular joint moved well and in harmony at open mouth position, and a rotational movement of the left temporomandibular joint was observed.