Bacterial Invasion of Infected Canals and Root Dentin of Human Teeth and Analysis of the Host-parasite Interaction at the Apex. - Elucidation of Pathogenesis of Refractory Cases-.

我们用免疫学方法检查了16种选定细菌在感染根管系统和感染根管壁的牙本质小管中的流行和定位。在本研究中，我们建立了一种新的方法，可以在切片准备过程中保持管内内容物。结果表明，该方法可用于分析选定细菌的定位，特别是在感染根管中。所有的样本显示细菌侵入根管，然而，只有70%的检查牙齿显示细菌侵入牙本质小管。在根管的根尖部分，75%的样本显示细菌入侵。变形链球菌是感染根管中检出最多的细菌。冠状部分以变形链球菌为主，中间部分以干酪乳杆菌为主，根尖部分以血链球菌和黑化普雷沃氏菌/中普雷沃氏菌为主。密螺旋体在根管各部位均缺乏。在牙本质小管中，有大量的核梭杆菌、乳酸解真杆菌、结瘤真杆菌、干酪乳杆菌和微胃链球菌，而很少有直弯曲杆菌、粘放线菌和齿龈t。即使在扩大牙根管组，65%的牙齿仍有细菌侵入牙本质小管。分析细菌的定位，冠状面三分之一的细菌入侵率高于根尖三分之一（p<0.05）。免疫组织学研究揭示了感染根管和牙本质中所选细菌的实际情况。本研究还表明，根管扩大术并不能完全清除根管感染牙根小管内的所有细菌。

We immunologically examined the prevalence and localization of 16 selected bacteria in the infected root canal systems and dentinal tubules of the walls of the infected canals. In this study, we established the new method which could maintain the canal contents during the preparation of the sections. This method was revealed to be useful to analyze the localization of selected bacteria especially in infected root canals.All of the samples showed bacteria invasion in the root canals, however, only 70 % of the examined teeth showed bacterial invasion in the dentinal tubules. In the apical portions of the root canals, 75% of samples showed bacterial invasion. Streptococcus mutans was the most abundant bacteria detected in the Infected root canals. And S. mutans was the predominant bacteria in the coronal portions, Lactobacillus casei was predominant in the middle portions, and Streptococcus sanguis and Prevotella nigrescens/Prevotella interimedia were abundant in the apical portions of the root canals. Treponema denticola was scant in all parts of root canals. In the dentinal tubules, Fusobacterium nucleatum, Eubacterium alactolyticum, Eubacterium nodatum, L. casei, and Peptostreptococcus micros were abundant, whereas Campylobacter rectus, Actinomyces viscosus, and T. denticola were scant. Even in the canal-enlarged group, invasion of bacteria in the dentinal tubules was observed in 65% of the teeth. Analyzing the localization of the bacteria, the coronal third of the root dentin showed higher bacterial invasion than the apical third (p<0.05).This immunohistological study revealed the actual condition of the selected bacteria in infected root canal and dentin. And this study also indicated that the canal-enlargement procedure could not completely remove all the bacteria in the dentinal tubules of the roots of teeth with infected canals.