Preliminary Study Of Repairing Mandible Defect By Distraction Osteogenesis With The Nonvascularized Transport Disc

Objective: To observe the differences between distraction osteogenesis(DO) with the nonvascularized transport disc(NTD) and the classical bifocal distraction osteogenesis(DO), investigate the mechanism of DO with NTD by establishing the repairing model of the dog's mandible defect by DO with NTD.Methods: Six adult dogs were divided into 3 groups randomly(n=2 in each group, which received a right mandibular osteotomy and were distracted for 10 days(1mm/day) and consolidated for 1, 4 or 12 weeks respectively. A customised internal distraction device was used to distract the mandible to unite the artificial madibular defact and NTD. Each group of dogs was killed on the 1th, 4th and 12th weeks of the consolidation period, and the specimens of NTD and it's surrounding regenerating tissue were harvested. Some pathological and morphological changes of specimens will be collected by naked eye, radiographs, histological analysis and scanning electron microscope(SEM). Results:There is a great quantity newly formed bone tissue in distraction gap and around NTD, most rich in the middle of NTD. The phenomenon of newly formed bone healing directly with NTD was found, and osteoclastes gathered on the part surface of NTD in 1 week after DO. Following with the lasting of the consolidation period, the regenerating bone was gradually becoming mature, which was integrated eventually with NTD and not distinguished by naked eye, radiographs, histological analysis and SEM in 12 weeks after DO.Conclusion: The defect of mandible can be repaired by DO with NTD, recovered integratelly the morphous and functions of mandible. The NTD may play important roles of osteoinduction, osteoconduction and osteogenesis, while the body of NTD may been rebuilded or absorbed with regeneration to follow during DO.