Distraction Osteogenesis For Bony Repair Of Cleft Palate By Persistent Elastic Force: Experimental Studies In Dogs

Part I The possibility of persistent elastic distractionosteogenesis for bony repair of cleft palate Objective The objective of this study was to explore the possibility of distraction osteogenesis for closing cleft and lengthening hard palate by persistent elastic force. Methods Ten 6-month mongrel dogs were divided into three groups: the control(n=2), sham control(n=2) and the experimental group(n=6). A 8mm X 25mm posterior hard palatal cleft was made surgically in six experimental dogs. Two lateral and anterior of cleft osteotomies were performed. After a 5-day latency period, distraction device made of NiTi-shape memory alloy was placed to active osteogenesis. A half of the distractors were left in place for 8 weeks after the management had achieved the desired. Plaster cast meterage and X-ray examination were performed at the beginning and end of distraction period. When the animals were executed separately at the end of distraction period and retention period, histological study was made on the new bone specimen. Results There was no self-repairing for cleft in sham control. In experimental group, two lateral transportation segments meet at midline of palate after 5-7-day distraction period. Two lateral palatal sucosal merged together and the posterior clefts were closed after 2-3-week distraction, the front clefts became seams of l-2mm-width. Meanwhile, hard palatines were lengthened backward obviously. New bone formation was found at the site of distraction in all experimental dogs at the time of death. X-ray and histological examination proved that DO induced bone rgeneratedsuccessfully. Comparison of the plaster casts of beginning and end of treatment revealed no change in the occlusion. Conclusion Distraction osteogenesis using the device of NiTi-shape memory alloy is an effective technique for closing cleft and lengthening hard palate in a canine cleft palate model.