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

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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.