The Animal Model's Establishment And Histological Study Of Nonvascularized Transport Disc Distraction Osteogenesis

Objective: To establish an animal model of nonvascularized transport disc distraction osteogenesis in dogs. To observe the histology and morphous of new bone formation of distraction area. To study the form mode and influential factor of new bone formation in the nonvascularized transport disc distraction osteogenesis and to further approach the ossific mechanism of DO, which offer a theory and experiment evidence for clinical application.Methods: The experimental object was 8 dogs. The mandibular defect was made firstly through partial mandibular ectomize for the experimental dogs and the length of defect was about 30mm from canines distant place. In operation, subtus dentoalveolar nerve vascular bundle was cut off. A transport disc was then made in the extraorgan and the length of transport disc was about 20mm. Then shift it to distal end of defect and resettle the intra-oral DO device. Mandibular defect was reconstructed at a rate of 1mm per day and rhythms of 1 time per day. Tetracycline was venously injected in the part of experimental animals. The animals from each group were killed at 1, 2, 4, and 12 weeks after bone distraction respectively. At last, gross, X-ray, histology and tetracycline fluorescent labeling of new bone tissue in the distraction zone were studied.Results: All animals completed successfully the distraction osteogenesis. Gross and histology showed that new bone's formation belonged to complete intramembrane osteogenesis. Ossification direction was from marginal periost to center. Ossification course was neogenesis and rebuild concomitance. The speed and quality of osteogenesis in the lingual side was better than in the buccal side.Conclusion: The animal model of nonvascularized transport disc distraction osteogenesis was successful and it was first time in international. Further, it offered a new method and idea for mandibular defect reconstruction. The mode of new bone's formation still belonged to complete intramembrane osteogenesis. The mode was coincident with ossific mode of vascularized transport disc distraction osteogenesis, but it wasn't coincident with orthodox theory. Otherwise, the adhesion of abradant periosteum was rather strong. After adhesion, it was hardly influencing for function. So don't emphasize to avoid avulsing lingual side's periosteum clinically.