Nagaoka S, Liu H J, Minemoto K, Kawagoe M
Department of Operative Dentistry and Endodontology, Kagoshima University Dental School, Kagoshima, Japan.
J Endod. 1995 Nov;21(11):546-51. doi: 10.1016/S0099-2399(06)80983-0.
The ability of Lactobacillus casei, Streptococcus sobrinus, Actinomyces viscosus, and Streptococcus salivarius to induce dental caries was determined in vitro. A class I cavity (depth: 2mm) was prepared in extracted human caries-free premolars to make dentin blocks. The blocks were inoculated with these four bacterial strains in a monoinfective fashion and were incubated under anaerobic conditions. In addition to the monoinfection groups, mixed-infection groups of L. Casei with S. sobrinus or A. viscosus were also prepared. Half of the culture medium was renewed every 3 days, and the pH of the medium was measured. After 4 or 12 wk, these dentin blocks were prepared by Brown-Brenn staining and by contact microradiography for light microscopic observation and for immunohistochemical staining. The final pH of the S. salivarius group was the highest among the experimental groups, at approximately 5.1; that of the others was approximately 4.3. Bacterial invasion into the dentinal tubules was observed in all but the S. salivarius group. Among the monoinfection groups, the S. sobrinus group showed the highest invasion rate, followed by the A. Viscosus group and the L. casei group. The invasion rate was also high in the mixed-infection groups. Immunohistochemical staining revealed invasion only by L. casei, and not by S. sobrinus and A. viscosus. The invasion rate by L. casei was higher in the mixed-infection group with either S. sobrinus or A. viscosus than in the monoinfection groups. These findings suggest that lactobacillus might play an important role in the initiation and progress of dentinal caries, and that this bacterial species might exhibit a cooperative cariogenicity when it coexists with other bacterial species that surpasses its individual cariogenicity.
在体外测定了干酪乳杆菌、远缘链球菌、粘性放线菌和唾液链球菌诱导龋齿的能力。在拔除的无龋人类前磨牙上制备I类洞（深度：2mm），制成牙本质块。将这些牙本质块以单感染方式接种这四种细菌菌株，并在厌氧条件下培养。除单感染组外，还制备了干酪乳杆菌与远缘链球菌或粘性放线菌的混合感染组。每3天更换一半培养基，并测量培养基的pH值。4周或12周后，对这些牙本质块进行Brown-Brenn染色和接触式显微放射摄影，用于光学显微镜观察和免疫组织化学染色。唾液链球菌组的最终pH值在各实验组中最高，约为5.1；其他组约为4.3。除唾液链球菌组外，在所有组中均观察到细菌侵入牙本质小管。在单感染组中，远缘链球菌组的侵入率最高，其次是粘性放线菌组和干酪乳杆菌组。混合感染组的侵入率也很高。免疫组织化学染色显示仅干酪乳杆菌侵入，远缘链球菌和粘性放线菌未侵入。干酪乳杆菌在与远缘链球菌或粘性放线菌的混合感染组中的侵入率高于单感染组。这些发现表明，乳杆菌可能在牙本质龋的发生和发展中起重要作用，并且当该细菌物种与其他细菌物种共存时可能表现出超过其个体致龋性的协同致龋性。
