Palatal distraction in a canine cleft palate model.

The purpose of this study was to determine whether the canine hard palate can be lengthened by distraction osteogenesis in a cleft palate model using a mostly submucosal distractor. Five mongrel dogs were used. After raising mucoperiosteal flaps, a midline strip of bone was removed from the hard palate of each dog to simulate the bony defect seen in a cleft palate. A transverse osteotomy was then made to separate the posterior segment of the hard palate from the anterior segment. Posterior osteotomies were also made laterally parallel to the teeth so that the 2 posterior segments (one on either side of the bony cleft) were mobile. An intraoral distractor that was mostly submucosal was attached to the anterior hard palate and both segments of the mobilized posterior hard palate. Radiopaque bone markers were placed, and x-rays were obtained. After a 10-day latency period, the distractor was expanded 0.675 mm per day until it had been lengthened 10.125 mm. Distractors were left in place for an additional 8 weeks. After distractor removal, animals were observed for an additional 8 weeks before euthanization. Follow-up x-rays and histologic examinations were performed. New bone formation was found at the site of distraction in all dogs at the time of death. This new bone was seen on the follow-up x-rays and on histologic examination of the hard palates using both hematoxylin and eosin staining and Masson's trichrome stain. Distraction osteogenesis using a mostly submucosal device is an effective technique for lengthening the hard palate in a canine cleft palate model. The technique may eventually provide an alternative treatment for velopharyngeal incompetence in humans that is more precise and involves less morbidity than existing treatments.