【作者】 麦华明；

【导师】 周诺；

【作者基本信息】 广西医科大学 ， 口腔临床医学， 2004， 硕士

【摘要】 目的：通过两种不同术式的比较，研究骨形态发生蛋白-2（BMP-2）、碱性成纤维细胞生长因子（bFGF）的表达水平和成骨的关系，探讨牵张成骨的成骨机制。方法：28只狗随机分为牵张成骨组和直接延长组各12只，以及正常对照4只，牵张组于双侧第一与第二磨牙之间将下颌骨截断，并装上牵张器将下颌骨固定，于术后第8天开始牵张，牵张频速率1mm/次/天，连续牵张10天后固定，将牵张器保留原处作为固定器，分别于牵张第6天、固定2周、固定8周各处死4只动物，切取双侧牵开区骨组织待测；而直接延长组则在相同的部位以相同的术式完成下颌骨截断术后直接拉开10mm后行钛板内固定，与牵张组的相应时期分别处死相同数量的动物，切取双侧拉开区组织待测，正常对照组，手术直接于第一及第二磨牙区切取相应骨组织待测。所有标本处理后均作常规HE染色和BMP-2、bFGF免疫组化染色分析，并分别于牵张完毕、固定2周、4周、8周时段对牵开区和拉开区拍X线片检查。结果：X线检查 见牵张组是从两断端边缘开始成骨，向中央靠拢，最终牵开区骨密度与周围正常骨组织相近，而直接延长组成骨速度慢，成骨量少，最终中央仍为低密度软组织影。HE染色 光镜检查可见牵张组牵张第六天在两骨断端附近即可见活跃的膜内成骨，牵张后固定2周，继续表现出活跃的膜内成骨现象，伴有少量的软骨内成骨，至固定第8周，牵开区几乎完全由新生的骨组织连接修复；而直接延长组仅早期在两骨断端附近可见活跃的膜内成骨，两周以后则以少量的软骨内成骨为主，中间区域仍为大量的纤维结缔组织,8周以后中央仍为软骨组织和纤维结缔组织间隔。免疫组化染色牵张组牵张中6天骨断端附近的新生编织骨边缘基质及周缘的活跃的成骨细胞、骨膜下及牵开区增生活跃的间充质细胞、成纤维细胞、胶原纤维基质均可见BMP-2、bFGF强阳性的染色。两组间的牵开区的BMP-2、bFGF染色平均灰度比较均无统计学差异（P>0.05）；牵张后固定2周，牵张组新生编织骨边缘的成骨细胞、软骨细胞、牵开区纤维结缔组织仍可见<WP=4>BMP-2、bFGF阳性染色，牵开区的染色平均灰度维持在较高水平，而直接延长组的BMP-2、bFGF在牵开区的染色强度明显降低，两组间BMP-2、bFGF平均染色灰度比较均有统计学差异（P<0.01）；牵张后固定8周，BMP-2、bFGF在牵张组和直接延长组的组织中的染色强度均明显减弱，仅在少数残留的软骨细胞、新骨基质及其周围的成骨细胞、成纤维细胞可见弱阳性染色,两组BMP-2、bFGF平均染色灰度比较均无统计学差异(P>0.05)。结论：牵张成骨以膜内成骨为主，达到良好的骨愈合，直接延长以软骨内成骨为主，成骨效果不稳定，容易导致成骨不良。在下颌骨牵张成骨过程中，在机械的牵张力和微创伤等多种因素刺激下，局部牵开区BMP-2和bFGF持续高表达。两种生长因子可能共同参与促进了牵开区大量新骨的形成。更多还原

【Abstract】 Objective: This study was designed to reveal the mechanism of expression and effect of Bone Morphogenetic Protein2(BMP-2) and basic fibroblast growth factor (bFGF) which result in successful osteogenesis, and to provided evidence for further application of bone growth factors to shorten the long period of distraction osteogenesis(DO), reconstruct bone defect and facilitate bone healing. Methods: Twenty-eight adult dogs were randomly divided into DO group (n=12) ，acute lengthening group(n=12) and normal group(n=4). All the dogs in DO group were underwent bilateral mandibular osteotomy between the first and second molars, and two custom-made distraction devices was fixed in the both two osteotomy regions of each dog. After a lantency period of 7 days post-operation, the distraction devices had been activated at a rate of 1mm per day ,four dogs were respectively sacrificed at days 6 of distraction period, weeks 2,8 of the consolidation after distraction for 10 days. All the dogs in acutely lengthened groups were underwent bilateral mandibular osteotomy as the DO group, both side of the mandible were acutely lengthed 10mm and were fixed by titanium plates, four dogs were respectively sacrificed at the same time of DO group, Callus of distraction gaps , lengthing gaps and the same regions of normal mandible were harvested. The change of histology was observed by HE staining micrograph examination. The spatial and temporal expression patterns of BMP-2 and bFGF were studied using immunohistochemistry. The X-ray examination was taken respectively at The first day, 2, 4, and 8 weeks after completion of distraction.Results: X-ray examination In DO group, The density of new bone was enhanced gradually from both side of osteotomy to the center of <WP=6>distraction gap, and appeared nearly the normal after 8 weeks of consolidation;In acute lengthening group, the rate of ossification appeared slower than DO group and the quantity of new formed bone seemed lesser, at last the center of lengthening gap still appeared low density. HE staining micrograph examination In DO group ,the active intramembranous ossification was seen at the osteotomized bone edges in 6 days of distraction, after 2 weeks of consolidation, the activity of intramembranous ossification was continued represented, accompanied with a few endochondral ossification; after 8 weeks of consolidation, the distraction gaps were nearly completely ossified. In the acutely lengthening group, active intramembranous ossification existed along the osteotomized bone edges in early stage too, but the major mode of new bone formation appeared change to be endochondral ossification after 2 weeks , fibril connective tissue and endochondral tissue were filled in the center area after 8 weeks. Immunohistochemistry In DO group and acutely lengthening group, during the distraction period, the strongly positive stain of BMP-2 and bFGF were both found in the osteoblasts around the newly formed trabecular bone and the bone formation front, mesenchymal cells and fibroblasts from the periosteum and distraction gap and the fibrous collagen. There was no statistic difference between the stain grays of two groups; after 2 weeks of consolidation, the positive stain of BMP-2 and bFGF were found in osteoblasts, cartilaginous tissue and fibrous connective tissue in the distraction gap of DO group, while the positive stain of BMP-2 and bFGF in acutely lengthening group were remarkably weakened. There were statistic difference between the stain grays of two groups (P<0.05); after 8 weeks of consolidation, the stain intensity of BMP-2 and bFGF in the two group were both markedly decreased, only faint positive stain was found in few rudimental cartilaginous tissue, fibroblasts, newly formed bone matrix and osteoblasts around it ,there <WP=7>was no statistic difference between the stain grays of two group(p>0.05). Conclusion: The major mode of new born formation in distraction osteogenesis is intramenbranous ossification, and result in bone union; the major mode of new bone form更多还原