下颌三焦点牵张成骨过程中新骨组织骨形成蛋白的时空表达与影像学研究

Temporospatial expressions of BMP and X-rays/CT imageologic study during trifocal mandibular distraction osteogenesis

目的观察下颌三焦点牵张成骨过程中新骨组织骨形成蛋白的分布表达及影像学特征。方法选取4只成年恒河猴,通过下颌前分骨截除术形成颏部正中联合骨缺损。在两侧下颌体部各制备一个输送盘,用自行研制的多平面牵张装置使双侧输送盘向前内方向缓慢移动并在颏部正中对接以修复颏部骨缺损。在牵张结束的第2、4、8与16周分别行X线或CT检查后处死,标本以抗骨形成蛋白(BMP)单抗免疫组化方法染色观察。结果免疫组化结果显示,牵张结束的第2周BMP广泛表达于牵开间隙的成骨细胞内,第4周成骨活跃,第8～16周BMP表达渐趋减弱。X线及CT影像显示新骨组织的钙化成熟是沿牵张方向逐渐发展,二者具有时相相关性。结论BMP在牵张成骨的早期起重要作用。X线及CT亦证明,在牵张弧形轨迹上,新骨组织从无到有,最终实现骨连续性及结构的恢复。

Objective To study the expression patterns of BMP and X-rays/CT Imageologic characteristics during trifocal mandibular distraction osteogenesis. Methods 4 monkeys were used in this study. The mandibular symphyseal defects were made by resection of the anterior part （ranged from canine to canine） of mandible. Bilateral transport disks （ranged from first premolar to first molar） were created in the remaining mandibular bodies, and a custom-made adjustable multiplanar distraction apparatus was applied to repair the artificial mandibular symphyseal defects by means of trifocal distraction osteogenesis. After a delay period of 7 days, the bilateral transport discs were distracted forward and inward simultaneously. X-ray films and 3-dimmensional CT scan were used to detect the bilateral transport segments movement and the new bone formation. One monkeys were sacrificed at 2,4,8 and 16 weeks respectively after the completion of distraction. The distracted calluses were harvested and processed for Anti-BMP immunohistochemistry studies. Results Anti-BMP immunohistochemistry study showed extensively positive DAB dye in early 2 weeks and continually positive expression of BMP in 4 weeks. The expression of BMP wore off gradually through the 8th to 16th weeks. The X-rays and CT imageologic study showed that the newly mineralized bone developed and matured along curved trace which was created by multiplanar trifocal distractor. The newly formed bone bridged the defect area completely and mandibular symphyseal defects were reconstructed at the end of the study. X-rays/CT imageologic characteristics showed kind of correlativity with immunohistochemistry findings. Conclusion BMP may play important roles at the early stage of distraction osteogenesis. X-rays/CT imageologic study also proves that new bone formation along the curved trace is dynamic and can eventually realized structural reconstruction.