AIM: To study the effects of MMP-2 and TIMP-2 on orthodontic root absorption in rats.METHODS: The root resorption model of 30 rats caused by orthodontic force was established.Samples were respectively collected on day 0, 1, 3, 5, 7,14 and 21 after treatment(n=5).Another 5 rats were used as the controls.The morphology of root absorption was observed by HE staining, MMP-2 and TIPM-2 expression was evaluated by immunohistochemical staining(IHCS).RESULTS: HE staining showed that root absorption started from day 3, with bone resorption lacunae formation confined to cementum, reached the peak at day 7,dentine was involved in the severe cases.After day 21 the root absorption degree reduced, osteoblasts gathered in the ares of root absorption.IHCS showed that MMP-2 and TIMP-2 positive expression mainly located in cytoplasm in root absorption area.Weak expression of MMP-2 was identified in control group.In treatment group, MMP-2 positive cells increased and reached the peak at day 7, gradually declined after day 14, and reduced more after day 21, but stronger than the controls.The expression of TIMP-2 was similar to that of MMP-2.CONCLUSION: MMP-2/TIMP-2 are involved in the metabolism of extracellular matrix in the process of root absorption.%目的:初步研究大鼠正畸牙移动性根吸收过程中MMP-2和TIMP-2的表达规律.方法:取8周龄SD大鼠35只, 5只用于正常对照, 30只用60 g的力牵拉上颌第一磨牙向近中移动以建立正畸牙移动性根吸收模型;于实验的0(空白对照组)、1、3、5、7、14、21 d各处死5只大鼠,取包括上颌第一磨牙的牙槽骨组织,HE染色观察形态,免疫组化染色法观察MMP-2和TIPM-2的表达.结果:加力3 d可见局限于牙骨质的骨吸收陷窝形成,此后逐渐加重,7 d时达到高峰,严重者累及牙本质;14 d时,根吸收程度减轻,根吸收部位可见成骨细胞聚集;21 d时,根吸收陷窝可见牙本质修复现象.
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