目的 检测并研究冠根部的牙本质内基质金属蛋白酶(M MPs)及其对牙本质胶原纤维降解的作用.方法 将牙本质粉经盐酸胍提取,然后经EDTA循环脱矿,再经盐酸胍提取.提取物经免疫印迹与酶谱分析检测基质金属蛋白酶-2,9(MMP - 2,9)及酶的活性.扫描电镜观察脱矿及脱矿后置于人工唾液中的冠根部牙本质表面结构变化.结果 免疫印迹结果显示提取物中含有MMP -2,9.酶谱分析结果显示提取物中MMP -2,9均具有活性.扫描电镜结果表明,脱矿的冠根部表面胶原纤维较完整；而脱矿后置于人工唾液中的牙本质表面胶原纤维断裂,结构紊乱.结论 冠根部牙本质中含有活性的MMP -2,9.脱矿过程中的低pH值能使牙本质中的MMP活化,在中性时可降解胶原纤维.%Objective This study was to determine matrix metalloproteinases in the crown and root dentin and their effects on the degradation of collagen fibers. Methods Dentin powder was extracted by guanidine, then demineralized for four times by EDTA,finally extracted by guanidine hydrochloride again. Matrix metalloproteinases and their activity in the extracted materials were measured by Western blot and SDS gel electrophoresis zymography. Scanning electron microscope was used to observe surface structure of demineralized crown and root dentin, as well as demineralized dentin which had been put into artificial saliva. Results MMP-2 and MMP-9 in the extracted materials were confirmed by western blot. More importantly, the protein acitivity of MMP-2 and MMP-9 from the crown and root dentin was verified by SDS gel electrophoresis zymography. It was indicated by SEM that the structural integrity of the collagen network of crown and root dentin still existed after determineralization, while collagenous fibril was destructed and the structrual integrity of crown and root dentin disappeared after being demineralized in artificial saliva. Conclusions MMP-2 and MMP-9 proteins have proved to present with activity in the materials extracted from the crown and root dentin. After being activated at low pH in demineraliza-tion, MMPs can degrade collagen in crown and root dentin.
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