Nishioka M, Shiiya T, Ueno K, Suda H
Department of Endodontics, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
Endod Dent Traumatol. 1998 Aug;14(4):163-73. doi: 10.1111/j.1600-9657.1998.tb00832.x.
The purpose of the present study was to evaluate the influence of bacterial infection on the pulpal and periodontal tissues in replanted teeth using germ-free and conventional rats. Forty maxillary and mandibular first molars from ten 6-week-old germ-free male Wistar rats were used. The animals and all materials were maintained in a germ-free environment inside vinyl isolators throughout the experimental periods. Twenty conventional male Wistar rats served as controls. The first molars were intentionally replanted immediately after extraction. At 3 days, and 1, 2, 4 and 8 weeks after replantation, animals were sacrificed and the replanted teeth were histopathologically evaluated. Diversity of pulp tissue response was notable in conventional rats, which initially showed various degrees of neutrophil infiltration and then displayed different types of response, including revascularization with reparative dentin formation and complete necrosis. Pulpal responses of germ-free rats were less variable, being characterized by an almost complete lack of neutrophil infiltration and a high frequency of bone-like tissue ingrowth. Typical inflammatory resorption was detected only in conventional rats, whereas a higher incidence of ankylosis was notable in germ-free rats. The present results may corroborate the concept that bacterial infection is a major cause of serious healing complications following tooth replantation, such as pulp necrosis and inflammatory root resorption. The difficulty in optimally controlling bacterial infection seems to be highly relevant to the complexity and unpredictability of the outcome of this procedure. It should also be emphasized that extensive mechanical damage to the periodontal tissues may trigger the development of unfavorable healing complications as ankylosis, even under strictly aseptic conditions.
本研究的目的是使用无菌大鼠和普通大鼠评估细菌感染对再植牙牙髓和牙周组织的影响。选用了来自10只6周龄无菌雄性Wistar大鼠的40颗上颌和下颌第一磨牙。在整个实验期间，动物和所有材料都置于乙烯隔离器内的无菌环境中。20只普通雄性Wistar大鼠作为对照。第一磨牙在拔除后立即进行有意再植。在再植后3天、1周、2周、4周和8周，处死动物并对再植牙进行组织病理学评估。普通大鼠牙髓组织反应的多样性显著，最初表现为不同程度的中性粒细胞浸润，随后表现出不同类型的反应，包括伴有修复性牙本质形成的血管再生和完全坏死。无菌大鼠的牙髓反应变化较小，其特征是几乎完全缺乏中性粒细胞浸润，且骨样组织长入的频率较高。仅在普通大鼠中检测到典型的炎性吸收，而无菌大鼠中骨粘连的发生率较高。目前的结果可能证实了细菌感染是牙齿再植后严重愈合并发症（如牙髓坏死和炎性牙根吸收）的主要原因这一概念。最佳控制细菌感染的困难似乎与该手术结果的复杂性和不可预测性高度相关。还应强调的是，即使在严格无菌条件下，对牙周组织的广泛机械损伤也可能引发如骨粘连等不良愈合并发症的发生。
