| The congenital or acquired deformity and defect, esp the deformity of mandible, is common in clinic. Most of them were caused by postoperation, trauma and inflammation, leading to dysfunction and physiognomy malformation. From 1992, McCarthy firstly introduced the use of extraoral distractor to treat deformity of mandible, distraction osteogenesis became an important method to correct oral and maxillofacial underdevelopment and formities of facial skeleton.Many animal experiments and clinic cases have been reported to investigate the medial-distal and vertical distraction in recent years. Such as dysostosis, defect of mandible,micrognathia,OSAS,palate cleft and so on.At the bottom of many reviews, this study designed bucco-lingular distraction of canine's mandible,in order to inquiry the possibility of bucco-lingular distraction.Also,the study might supply a experimental basis of three-dimensional distraction.In this experiment, a half-buried distractor has been used after the square osteotomy to unilateral cortical bone of twelve canine's bilateral mandible. The bone segment of left mandible was elongated buccally after a consolidation phase of 7 days. The distraction protocol consisted of a rate of 0.5mm twice daily for 7 days, while right bone segment didn't proceeddistraction as control. The new osteogenesis were obtained and decalcified and paraffin slices were made respectively on the 4th day, the 1st, 2nd, 4th, 6th, 8th week after distraction complete. The slices were stained with HE and modified Mallory's. The results indicated that the left distraction segment obviously eminence buccally. The newly generated bone could be observed in distraction gap and it calcificate well at 8th week. The newly bone were continuous with circumference normal bone.Other specimens didn't decalcify and processed for SEM evaluation and Ca/P ratio assay.With elongation time of the consolidation,the contents of Ca, P bundle were found to be elevated in the experiment. The newly generated bone decalcified as well as nomal bone with the maturity of distracted callus. It also shows that Ca, P element took part in the whole procedure of bone generation.Many growth factors have been proved to produce a marked effect onDO. In this study, The expression of integrin β1 in bone tissue, especially in the membrane of osteoblast and osteoclast was detected differently. Inosteoblasts, integrin β1 expressed increased on the 1 st week, maximum on the 2nd~4th week and normal on the 8th week. In osteoclast, inferior positive expression of integrin β1 was observed on the 4th day, decreased on the 1 st week and disappeared on the 4th week.The increased expression of integrin β 1 in osteoblast suggested that integrin β1 has a critical influence on distraction osteogenesis, and likely relates to the mechanical signal transduction. The interaction of the integrin and other signal molecul and the strain delivering from inter-cells should be studied further and deeply in future.In general, the experiments in this study showed that bucco-lingulardistraction is feasible and coincident with the principle of DO by XRS. The Ca, P element had been proved to participate the whole distraction. Integrin β1 probably took part in transducting the mechanical signal to osteogenesis's signal.The results of the study might provide effective basis on treating HFM in clinic. |
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