Amount of Bone Lengthening Affects Blood Flow Recovery and Bone Mineralization After Distraction Osteogenesis in a Canine Cleft Palate Model

Objectives: Distraction osteogenesis has been applied to the craniofacial region. To reduce the cleft width of patients with cleft lip and palate, alveolar bones are distracted toward the cleft. However, no reports have described limitations to the amount of lengthening that can be achieved by distraction osteogenesis in this area. Therefore, we investigated the healing process following different extents of distraction osteogenesis using a canine cleft palate model. Methods: A 10-mm bone defect was made in the palates. A bony segment including the canine was prepared and translocated into the defect area at a rate of 1 mm/d for 6 or 10 days, resulting in two groups (6- and 10-mm groups). Canine pulpal blood flow was monitored for 100 days with Doppler flowmetry. Then, the animals were sacrificed and the regenerated bone area was evaluated radiologically and histologically. Statistical significance was confirmed with the Mann-Whitney rank test. Results: Pulpal blood flow in the 6-mm group recovered to original levels earlier than in the 10-mm group. Cortical bone density in the regenerated bone, measured by peripheral quantitative computed tomography, was significantly greater in the 6-mm group than in the 10-mm group. The amount of regenerated bone in histologic sections was also significantly greater in the 6-mm group. Conclusion: We clearly showed that healing progress depends on the extent of distraction osteogenesis, highlighting the importance of limited distraction osteogenesis in the alveolar area.