In cases of severe mandibular prognathism, hypergrowth of the mandible is frequently complicated by maxillary undergrowth. Recently, two-jaw surgery has been performed in such cases, in which gradual advancement of the maxilla by distraction osteogenesis, and then posterior shift of the mandible by sagittal split ramus osteotomy are carried out. To treat mandibular prognathism complicated with maxillary undergrowth, we performed gradual advancement of maxilla by using an internal distraction device, and then carried out sagittal split ramus osteotomy approximately 5 months after.
The patient was an 18-year and 4 month-old male with malocclusion, and was diagnosed as having skeletal class III deformities with maxillary undergrowth and open bite. After preoperative orthodontic treatment, the maxilla was advanced approximately 10mm by distraction osteogenesis. About 5 months after, the mandible was posteriorly shifted by 10mm on the left side, and 12mm on the right side by sagittal split ramus osteotomy.
As a result, the concavity of the middle face and the mandibular prognathism were improved. Good and stable occlusion was obtained. Furthermore, improvement in speech function by this treatment was also confirmed.
