Distraction osteogenesis of the mandible with a modified intraoral appliance: a pilot study in miniature pigs.

The purpose of this study was to evaluate an intraoral, nontooth-borne, submucosal distraction appliance in the pig mandible from a clinical, radiographic, and histologic perspective. Intraoral distraction appliances were fabricated, tested for strength, and then adapted and rigidly fixated to the mandibles of three growing miniature Yucatan pigs. A bicortical osteotomy was performed on the right side of the mandible, and a buccal and lingual corticotomy on the left. Two amalgam markers were placed on each side of the osteotomy/corticotomy sites as references. Measurements were taken to evaluate the length and vector of the distraction site, and radiographs were obtained perioperatively. After a latency period of 5 days, distraction was commenced and continued for 13 days at a rate of 1 mm/day. Clinical evidence of distraction was apparent in all cases, with resulting Class III skeletal deformities. Distraction progressed further for the corticotomy sides than the osteotomy sides because of distraction device failure. Radiographic examination revealed increased bone density at the periphery of the distracted callus, with less density apparent centrally. Histologic examination showed fibrous connective tissue in the center of the callus, with cartilage and osteoid formation at the periphery. Bone formation was parallel to the vectors of distraction in all cases. This study confirms that the use of a modified intraoral appliance for distraction osteogenesis is feasible. Use of this device overcomes many of the problems associated with extraoral devices and may have clinical applications.