Yoshiba K, Yoshiba N, Nakamura H, Iwaku M, Ozawa H
Department of Operative Dentistry and Endodontics, Niigata University School of Dentistry, Japan.
J Dent Res. 1996 Aug;75(8):1590-7. doi: 10.1177/00220345960750081101.
Exposed dental pulp is known to possess the ability to form a hard-tissue barrier (dentin bridge). The exact mechanisms by which pulp cells differentiate into odontoblasts in this process are unknown. Fibronectin has been demonstrated to play a crucial role in odontoblast differentiation during tooth development. This study tested the hypothesis that fibronectin is involved in the initial stages of replacement odontoblast differentiation and reparative dentin formation. We observed its immunohistochemical localization during dentin bridge formation in human teeth, after pulp was capped with calcium hydroxide [Ca(OH)2]. One day after the capping, precipitation of crystalline structures was observed at the TEM level in association with cell debris at the interface between the superficial necrotic zone and underlying pulp tissue. This layer of dystrophic calcification showed positive reaction for fibronectin, and pulp cells appeared to be closely associated with this layer, seven to ten days post-operatively. At 14 days, an alignment of cells, some of which were elongated and odontoblast-like, was observed adjacent to the fibronectin-positive irregular matrix. Between the cells, corkscrew fiber-like fluorescence was visible. At 28 days, the irregular fibrous matrix was followed by the formation of tubular dentin-like matrix lined with odontoblast-like cells. Therefore, it would seem that fibronectin associated with the initially formed calcified layer might play a mediating role in the differentiation of pulp cells into odontoblasts during reparative dentinogenesis, after pulp was capped with Ca(OH)2.
已知暴露的牙髓具有形成硬组织屏障（牙本质桥）的能力。在此过程中，牙髓细胞分化为成牙本质细胞的确切机制尚不清楚。已证明纤连蛋白在牙齿发育过程中的成牙本质细胞分化中起关键作用。本研究检验了纤连蛋白参与替代成牙本质细胞分化和修复性牙本质形成初始阶段的假说。我们观察了用氢氧化钙[Ca(OH)₂]覆盖牙髓后，人牙牙本质桥形成过程中纤连蛋白的免疫组织化学定位。覆盖后一天，在透射电镜水平观察到晶体结构沉淀，与表层坏死区和下方牙髓组织界面处的细胞碎片相关。术后7至10天，这层营养不良性钙化对纤连蛋白呈阳性反应，牙髓细胞似乎与该层紧密相关。术后14天，在纤连蛋白阳性的不规则基质附近观察到细胞排列，其中一些细胞伸长且类似成牙本质细胞。细胞之间可见螺旋状纤维样荧光。术后28天，不规则纤维基质之后形成了由类似成牙本质细胞的细胞排列的管状牙本质样基质。因此，在用Ca(OH)₂覆盖牙髓后，与最初形成的钙化层相关的纤连蛋白似乎可能在修复性牙本质形成过程中牙髓细胞向成牙本质细胞的分化中起介导作用。
