上颌快速扩弓腭中缝血管内皮生长因子的时空表达与新骨形成的相关性研究

Correlation between vascular endothelial growth factor temporal expression and new bone formation in midpalatal suture during rapid maxillary expansion

目的探讨上颌快速扩弓扩张期和固定期兔腭中缝组织血管内皮生长因子(VEGF)的时空表达模式以及新骨形成情况。方法将44只新西兰大白兔随机分为11组:实验组(共5组)、对照组(共5组)、对照0组,每组4只。用螺旋分裂基托扩大矫治器(Haas矫正器)扩张兔上牙弓,快速扩张2周,固定4周。在安装扩张器当天(对照0组)、快速扩张第1、2周、固定第1、2、4周(实验组和对照组)取兔上颌骨腭中缝组织块,采用免疫组织化学法检测VEGF在腭中缝组织中的分布和表达变化,采用过碘酸-Schiff染色法观测新骨形成。结果快速扩张的腭中缝可见高水平的VEGF表达,VEGF阳性信号主要定位于血管内皮细胞胞浆和增殖活跃的成骨细胞胞浆。对照组VEGF在整个实验过程中均呈弱阳性表达。实验组快速扩张第1周、快速扩张第2周、固定第1周、固定第2周VEGF蛋白表达量均高于对照组。随着机械应力快速扩张,实验组VEGF蛋白表达量逐渐上升,固定1周达峰值后逐渐下降。实验组新骨形成的量均高于对照组,新骨形成的量逐渐上升,固定2周达峰值后逐渐下降。结论上颌快速扩弓产生的机械牵张力可以导致VEGF生成增加从而促进血管及新骨的生成。

Objective This study aims to investigate the temporal pattern of expression of vascular endothelial growth factor（VEGF） and new bone formation during midpalatal suture expansion osteogenesis for rapid maxillary expansion.Methods A total of 44 New Zealand white rabbits were randomly assigned to 11 groups,namely,five experimental groups,five control groups,and one control 0 group.A Haas appliance was used for the rapid expansion of the midpalatal suture;rapid expansion was set for 2 weeks and fixed for 4 weeks.The tissue of the maxillary midpalatal suture was harvested on the day of installing rapid expansion（control 0 group）,on weeks 1 and 2 for rapid expansion,and on weeks 1,2,and 4 for fixed（experimental group and control group,respectively）.The immunohistochemical method was used to detect distribution and expression of VEGF,and new bone formation was observed with periodic acid-Schiff.Results Higher VEGF expressions are observed after midpalatal suture distraction osteogenesis.Positive staining for VEGF is mainly noted in the vascular endothelial cells,and the active osteoblasts are at the edge of a newborn trabecular bone.A weak VEGF expression is detected among cells in the control group.The VEGF expression of the experimental group is higher than that of the control group in rapid expansion weeks 1 and 2 and in fixed weeks 1 and 2.The expression of VEGF in the experimental group increases significantly and peaks at fixed week 1,and then gradually decreases.The amount of newly formed bone in the experimental groups is always higher than that in the control group;moreover,it increases significantly and peaks at fixed week 2,and then gradually decreases.Conclusion The mechanical strain created by rapid maxillary expansion generates a sequence of VEGF cellular events that lead to increased vascularization and subsequent new bone formation.