Distraction osteogenesis of the ascending ramus for mandibular hypoplasia using extraoral or intraoral devices: A report of 8 cases

Purpose: This report presents the results of distraction osteogenesis using unidirectional extraoral and intraoral devices in 8 patients with differen t grades of vertical mandibular ramus hypoplasia. Patients and Methods: Eight patients with hypoplastic mandibles underwent u nilateral lengthening of the ascending ramus using unidirectional extraoral or intraoral devices, intraoral mandibular distraction was performed on 5 patients with deficiencies of the vertical ramus up to 24 mm. External devi ces were used in 3 patients with more severe hypoplasias. An intraoral oste otomy was performed, and progressive distraction at rates of 0.5 mm/12 hour s was initiated after 5 days. Once the desired length was reached, the devi ce was maintained in place for 8 to 12 weeks. Three-dimensional computed to mography scans were taken in all the patients to plan the procedure and to compare the changes postoperatively. Results: Successful distraction osteogenesis was achieved in all patients. The amount of mandibular lengthening ranged from 17 to 32 mm. Complications with the external devices such as rotation of the proximal bony fragment ( 2 cases) and loosening of the external screws at the end of the consolidati on period (1 case) were observed. Conclusions: The results suggest that the intraoral device can be used as t he method of choice for distraction osteogenesis of the ascending ramus of the mandible in patients with large deficiencies. Preoperative and postoper ative 3-dimensional computed tomographic scans are essential in treatment p lanning. (C) 2000 American Association of Oral and Maxillofacial Surgeons.