胶原纤维和基质金属蛋白酶9在大鼠正畸牙根吸收中的表达及意义

Expression and significance of collagen fiber and matrix metalloproteinase-9 during orthodontic root resorption in rats

背景:牙根吸收是正畸治疗中最常见的并发症,也是当前正畸研究中的热点,目前关于牙根吸收过程中不同时间点下牙周组织胶原纤维的重塑过程及其与基质金属蛋白酶9的关系尚不清楚。目的:研究在正畸源性牙根吸收过程中,压力侧不同时间点牙周组织中胶原纤维重塑和基质金属蛋白酶9的表达情况。方法:选取30只8周龄雄性Wistar大鼠,牵拉左侧上颌第一磨牙向近中移动,建立正畸牙移动模型(实验组),右侧第一磨牙不做任何处理(对照组)。加力后1,3,5,7,14,21 d,利用组织形态学技术观察分析牙槽骨和牙根表面、牙周组织胶原纤维变化以及基质金属蛋白酶9表达情况。结果与结论:①苏木精-伊红染色和Masson三色染色证实,与对照组相比,加力后不同时间点实验组牙槽骨和牙根表面均发生不同程度的牙根吸收,牙周组织胶原纤维发生结构重构,在7,21 d重构最显著,并且随加力时间延长单位面积内胶原纤维表达先减少后增多;②免疫组织化学染色证实,与对照组相比,实验组基质金属蛋白酶9表达增多,随加力时间延长基质金属蛋白酶9表达量呈现先增多后减少的趋势;Pearson相关分析显示,基质金属蛋白酶9与牙周组织胶原纤维的表达具有负相关性(r=-0.933,P<0.01);③结果说明,在大鼠正畸牙牙根吸收过程中,随加力时间延长牙周组织中胶原纤维呈现动态变化,基质金属蛋白酶9的表达水平与胶原纤维的动态变化和牙根吸收活动的变化趋势有关。

BACKGROUND:Root resorption is the most common complication in orthodontic treatment,and is also a hot topic in current orthodontic research.Currently,the remodeling process of collagen fibers in the inferior periodontal tissue and its relationship with matrix metalloproteinase-9 remain unclear at different time points during root resorption.OBJECTIVE:To investigate the remodeling of collagen fibers and the expression of matrix metalloproteinase-9 in the inferior periodontal tissue at different time points on the pressure side during orthodontic root resorption.METHODS:Thirty eight-week-old male Wistar rats were selected,and the orthodontic tooth movement model was established by pulling the left maxillary first molars towards the near middle in the experimental group,and the right side was not treated as the control group.The changes of collagen fibers and expression of matrix metalloproteinase-9 in alveolar bone,root surface and periodontal tissue at 1,3,5,7,14,and 21 days were observed and analyzed by histomorphology after force application.RESULTS AND CONCLUSION:(1)Hematoxylin-eosin staining and Masson's trichrome staining results confirmed that compared with the control group,the alveolar bone and tooth root surface of the experimental group had different degrees of resorption.The periodontal tissue collagen fibers underwent structural remodeling.The remodeling was most significant at 7 and 21 days.The expression of collagen fibers per unit area decreased first and then increased with the extension of the force.(2)Immunohistochemical staining confirmed that compared with the control group,the expression of matrix metalloproteinase-9 in the experimental group increased.The expression level showed a trend of first increasing and then decreasing with the extension of the application time.Pearson correlation analysis confirmed that the matrix metalloproteinase-9 expression was negatively correlated with the expression of collagen fibers in periodontal tissues(r=-0.933,P<0.01).(3)The above results indicate that during orthodontic tooth root resorption in rats,the collagen in periodontal tissues is prolonged with time of stress.The expression level of matrix metalloproteinase-9 is related to the dynamic changes of collagen fibers and the changing trend of tooth root resorption.