Higashi T, Okamoto H
Department of Endodontology and Periodontology, Hiroshima University School of Dentistry, Japan.
J Endod. 1996 Apr;22(4):168-72. doi: 10.1016/S0099-2399(96)80094-X.
The purpose of this research was to study under undecalcified conditions the presence, ultrastructural features, and contributions of the degenerative zone beneath the necrotic zone and whether it had effects on the formation of reparative dentin in canine incisors and premolars. The research was conducted over a period of 14 days after experimental pulpotomy using calcium hydroxide as a pulp-capping agent. On the first day following pulp exposure and capping with calcium hydroxide, electron-dense spherical bodies were observed under the necrotic zone. Energy dispersive X-ray point analysis confirmed that these electron-dense deposits contained calcium and phosphorus. By the third day, varying amounts of minute von Kossa-positive granules could be observed light-microscopically between the two zones of necrosis and underlying vital pulp tissue. Migration and proliferation of pulpal cells, most probably mesenchymal cells, were observed adjacent to the von Kossa-positive zone. The ultrastructure of the von Kossa-positive zone consisted of degenerated cells, electron-dense spherical bodies, and electron-dense shortened dilating fibrils. By the seventh day, short cylindrical-shaped cells collected at the coronal end of the vital pulp tissue. By the fourteenth day, the specimens having a uniform von Kossa-positive zone exhibited rapid differentiation of odontoblasts and tubular dentin formation. In contrast, only some specimens having an irregular von Kossa-positive zone exhibited osteodentin formation and the beginning of odontoblast differentiation beneath the osteodentin. These findings suggest that this calcified degenerative zone has an important effect on the reparative process of pulp tissue after pulpotomy.
本研究的目的是在未脱钙条件下，研究犬切牙和前磨牙坏死区下方退变区的存在情况、超微结构特征及其作用，以及它是否对修复性牙本质的形成有影响。在使用氢氧化钙作为盖髓剂进行实验性牙髓切断术后14天进行了该研究。在牙髓暴露并用氢氧化钙覆盖后的第一天，在坏死区下方观察到电子致密的球体。能量色散X射线点分析证实这些电子致密沉积物含有钙和磷。到第三天，在坏死的两个区域与下方的活髓组织之间，通过光学显微镜可以观察到不同数量的微小冯·科萨阳性颗粒。在冯·科萨阳性区附近观察到牙髓细胞，很可能是间充质细胞的迁移和增殖。冯·科萨阳性区的超微结构由退变细胞、电子致密球体和电子致密的缩短扩张纤维组成。到第七天，短圆柱形细胞聚集在活髓组织的冠端。到第十四天，具有均匀冯·科萨阳性区的标本显示成牙本质细胞快速分化和管状牙本质形成。相比之下，只有一些具有不规则冯·科萨阳性区的标本显示骨样牙本质形成和成牙本质细胞在骨样牙本质下方开始分化。这些发现表明，这个钙化的退变区对牙髓切断术后牙髓组织的修复过程有重要影响。
