A new approach to repairing cleft palate and acquired palatal defects with distraction osteogenesis

Cleft palate (CP) is one of the most common human congenital deformities, and acquired palate defects after trauma or tumour resection are also common. In this study, distraction osteogenesis (DO) for CP and other palatal bone defects was evaluated. Twenty cats were assigned randomly to 3 groups of (1) 15, (2) 3 and (3) 2 cats. In groups 1 and 2, a rectangular ostectomy, in the posterior of the palatal bone shelf, was performed in the sagittal axis to establish the CP defect model. At the same time, a pure titanium intraoral distractor was fixed to molar teeth with brackets and to the palatal bone shelf across the defect with titanium miniscrews bilaterally. Four weeks later, a secondary transport disc (TD) osteotomy was performed, and gradual DO treatment started at 0.4mm twice a day, after 6 days of latency. DO was performed until the TD reached the opposite margin over the gap in 5-6 days. Three cats each of group 1 were killed at 2, 4, 6, 8 and 12 weeks after completion of DO. In group 2, the bone and soft-tissue defects were untreated until death 6 weeks later. Group 3 cats (control) were killed after 6 weeks. The TD successfully recombined with the opposite palatal bone stump, and proportional expansion of the overlay mucoperiosteal flap was achieved. Intramembranous bone formation was revealed: parallel collagen bundles gradually deposited on new bone trabeculae while the proliferative osteoblasts produced bone matrix. The bone defect was finally reconstructed by de novo osteogenesis. The control group was observed to have no spontaneous repairing. These results suggest that the CP defect was reconstructed by osteogenesis in situ, and the soft tissues expanded simultaneously to achieve functional correction. The intraoral distractor provided both effective distraction and stability.