A study on mechanisms of tissue repair and regeneration of the dentin-pulp complex

本研究旨在阐明牙本质牙髓复合体的组织修复和/或再生机制。结果表明：1.在小鼠磨牙发育过程中，MMP-2、MMP-9和MT 1-MMP在牙上皮和间充质中均有表达。相比之下，TIMPs（1-3）表达差异。TIMPs在牙胚发育过程中的时空分布规律表明，TIMPs在牙胚发育过程中起着多种内在作用。2.形成修复性牙本质的成牙本质细胞样细胞表达TGF-βs，尤其是β2和β3，同时也表达TGF-β II型受体，这表明形成修复性牙本质的细胞表达成牙本质细胞表型，TGF-β 1表达成牙本质细胞表型。βs可能参与了盖髓后修复性牙本质形成过程中替代性成牙本质细胞的分化。3.正常牙洞制备引起MHCII类分子表达细胞分布的改变，尽管这种变化似乎是可逆的。与此相反，在去龋和修复的牙齿中，抗原呈递和细胞和/或体液免疫反应似乎持续存在，即使在治疗后。4.用810 nm-GaAlAs半导体激光照射大鼠磨牙牙面，评价牙髓的反应。这种激光在一定的功率设置下可以诱导三级牙本质的形成，而不会损伤硬组织，也不会引起牙髓中的炎症反应。

This study aims to elucidate mechanisms of tissue repair and/or regeneration of the dentin-pulp complex. Several factors involved in cell differentiation during tooth development and reparative dentinogenesis were analyzed.The results were as follows :1.During mouse molar tooth development, MMP-2,-9,and MT1-MMP were expressed in the dental epithelium and mesenchyme. In contrast, TIMPs(1-3) were differentially expressed. The distinct temporospatial distribution patterns of the TIMPs suggest that these inhibitors play several intrinsic roles during tooth development.2.The odontoblast-like cells forming reparative dentin expressed TGF-βs, especially β2 and β3, and also TGF-β type II receptor, suggesting that cells that form reparative dentin express odontoblast phenotype and that TGF-βs may be involved in the differentiation of replacement odontoblasts during reparative dentinogenesis after pulp capping.3.Cavity preparation in normal teeth caused alteration in the distribution of MHC class II molecule-expressing cells, although this change appears to be reversible. By contrast, in the caries-removed and restored teeth, antigen presentation and cellular and/or humoral immunoresponses would seem to persist, even after treatment.4.The pulpal responses to the irradiation of tooth surfaces with an 810nm-GaAlAs semiconductor laser were evaluated in the rat molars. This laser at certain power settings could induce the formation of tertiary dentin without hard tissue injury nor evoking inflammatory reactions in the pulp.