Rungvechvuttivittaya S, Okiji T, Suda H
Department of Endodontics, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
Arch Oral Biol. 1998 Sep;43(9):701-10. doi: 10.1016/s0003-9969(98)00044-2.
Bacterial infection of the dental pulp is a major hindrance to successful pulp regeneration after tooth replantation. This study examined how macrophages and class II molecule-expressing cells of the pulp respond to tooth replantation, on the hypothesis that they contribute to the defence and repair of the traumatized pulp. Upper right first molars of 5-week-old male Wistar rats were replanted immediately after extraction; contralateral untreated teeth served as controls. Pulpal cells expressing macrophage-associated antigens were immunohistochemically demonstrated at 0 h (immediately after the replantation) to 84 days postoperatively using antirat monoclonal antibodies OX6 (anti-class II molecules), ED1 (pan-macrophage antibody, reactive also with dendritic cells) and ED2 (anti-resident macrophages). Between 3 and 7 days postoperatively, ED1+ and OX6+ cells, but not ED2+ cells, were concentrated in areas of degeneration formed in the coronal pulp, and frequently showed a marked accumulation along the pulp-dentine border of the cuspal area. Confocal laser scanning microscopy revealed that some of the OX6+ cells with a dendritic profile extended several cytoplasmic processes into the dentinal tubules communicating with the enamel-free area at the tip of the cusp. From 14-84 days, approx. two-thirds of specimens exhibited pulp-tissue regeneration with increasing formation of reparative dentine. Following the formation of sound reparative dentine, cells positive to each antibody were distributed more centrally in the pulp than in the controls, and thus did not show any accumulation along the pulp-dentine border. However, in the other specimens where a bone-like hard tissue had formed in the pulp chamber, many ED1+ and OX6+ cells were still concentrated in the remaining pulp tissue and showed a marked accumulation along the pulp dentine border. Few ED2+ cells were observed in these specimens. These findings suggest that, following tooth replantation, exudative macrophages are actively engaged in eliminating dentinal tubule-derived infectious stimuli and that class II molecule-expressing cells, most probably containing dendritic cells, are positioned strategically at the outermost portion of the injured pulp to monitor incoming antigens. The intensity of the pulpal defence reaction may be dependent on the status of hard-tissue formation, which influences the amount of incoming antigens.
牙髓的细菌感染是牙齿再植后牙髓成功再生的主要障碍。本研究探讨了巨噬细胞和牙髓中表达II类分子的细胞对牙齿再植的反应，假设它们有助于受伤牙髓的防御和修复。5周龄雄性Wistar大鼠的右上第一磨牙在拔除后立即进行再植；对侧未处理的牙齿作为对照。使用抗大鼠单克隆抗体OX6（抗II类分子）、ED1（全巨噬细胞抗体，也与树突状细胞反应）和ED2（抗驻留巨噬细胞），在术后0小时（再植后立即）至84天通过免疫组织化学方法显示表达巨噬细胞相关抗原的牙髓细胞。术后3至7天，ED1+和OX6+细胞而非ED2+细胞集中在冠髓形成的变性区域，并经常沿牙尖区域的牙髓-牙本质界显著积聚。共聚焦激光扫描显微镜显示，一些具有树突状形态的OX6+细胞将几个细胞质突起延伸到与牙尖尖端无釉质区域相通的牙本质小管中。从14天到84天，约三分之二的标本表现出牙髓组织再生，修复性牙本质形成增加。在形成良好的修复性牙本质后，每种抗体阳性的细胞在牙髓中的分布比对照组更集中于中央，因此未沿牙髓-牙本质界出现任何积聚。然而，在牙髓腔中形成骨样硬组织的其他标本中，许多ED1+和OX6+细胞仍集中在剩余的牙髓组织中，并沿牙髓牙本质界显著积聚。在这些标本中观察到很少的ED2+细胞。这些发现表明，牙齿再植后，渗出性巨噬细胞积极参与消除牙本质小管来源的感染性刺激，并且表达II类分子的细胞，很可能包含树突状细胞，战略性地定位在受伤牙髓的最外层以监测进入的抗原。牙髓防御反应的强度可能取决于硬组织形成的状态，这会影响进入抗原的量。
