MICROBIOLOGICAL ASPECTS OF ROOT SURFACE CARIES

我们在这个项目中研究的广泛目标仍然是 阐明不同菌斑微生物作为龋病病原的作用 代理商和各种推定的致龋决定因素的整合 统一的龋齿病因概念。 一项重大努力将涉及 噬菌斑16 SrRNA探针设计与验证 有机体 目标微生物为S。mutans、S.远缘种 包括非变异链球菌（non-MS）（种特异性 探针）、放线菌、双歧杆菌、乳杆菌和韦荣氏球菌 （所有基因特异性探针），也许还有其他一些细菌。 在 与其他可用的方法相比，探针将允许快速和 这些龋相关菌斑生物的准确计数。 他们的 将在一个大型的临床试验中确定与人类根龋的关系。 临床研究（Clinical Core）。 在这方面特别值得注意的是， 所谓的“低”pH非MS，非MS的一段能够 产酸菌在低pH下产酸，如它们在糖肉汤中的“最终”pH所示。 我们之前的发现表明，除了变异基因 链球菌，这些生物体值得认真考虑， 可能是第二梯队的致龋菌斑生物。 此外，DNA 探针分析可能有助于进一步揭示 这些和其他口腔链球菌。 这些非MS的探针鉴别 物种将与其“最终”pH值的分析相结合。 相同探针鉴定物种的菌株的“最终”pH值将 允许直接定量斑块中的“低pH”非MS片段。 还将获得其他靶微生物的“最终”pH值数据 使用来自大型研究（临床核心）和其他来源的样本 (e.g.培养物收集）。 将获得类似的数据， 这些生物体关于它们的酸耐受性（能够 在酸性pH下生长/存活）。 这将产生一个全面的画面， 与两种主要龋相关细菌相关的菌斑孔 性状，即在酸性菌斑pH和酸性条件下的产酸能力 宽容，并将进一步帮助建设一个综合的 龋齿病因的概念。 原位鉴定的研究 细菌与免疫细胞化学的关系，根龋将重点 首先是全面查明 牙本质的“前进细菌前沿”。 这将与一个 分析蚀变牙本质区域的矿物质含量， 根据我们的研究结果，似乎是由于单一类型的行动， 有机体。 这项工作可能会产生非常重要的新数据 不同菌斑微生物的致龋性。 后来，这项工作将在 扩大与比较的组成菌斑植物群 与完整和改变的牙骨质或牙本质有关。

The broad aim of our studies in this project continues to be the elucidation of the role of different plaque organisms as caries-etiologic agents and the integration of various putative cariogenic determinants into a unified concept of caries causation. A major effort will involve the design and validation of 16S rRNA-based DNA probes for plaque organisms. Target organisms will be S. mutans, S. sobrinus and species comprising the non-mutans streptococci (non-MS) (Species-specific probes), Actinomyces, Bifidobacterium, Lactobacillus and Veillonella (genous-specific probes for all), and perhaps some other bacteria. In contrast to other available methods, the probes will permit the rapid and accurate enumeration of these caries-relevant plaque organisms. Their association with human root caries will be determined in a large clinical study (Clinical Core). Of particular interest in this regard will be to so-called 'low'-pH non-MS i.e., a segment of the non-MS capable of acidogeneis at low pH as indicated by their 'final' pH in sugar broth. Our previous findings have suggested that, besides the mutans streptococci, these organisms warrant serious consideration as a, perhaps, second echelon of cariogenic plaque organisms. Further, DNA probe analysis may help to unravel further the difficult taxonomy of these and other oral streptococci. Probe identification of these non-MS species will be coupled with analysis of their 'final' pH. Homogeneity of the 'final' pH of strains of the same probe-identified species will permit direct quantitation of the 'low-pH' non-MS segment in plaque. Data on 'final' pH will also be obtained for the other target organisms using samples from the large study (Clinical Core) and other sources (e.g. Culture Collection). Similar kind of data will be obtained for these organisms with respect to their acid tolerance (ability to grow/survive at acidic pH). This will yield a comprehensive picture of the plaque fora with respect to two major caries-relevant bacterial traits, i.e. capability for acidogenesis at acid plaque pH and acid tolerance, and will further aid in the construction of an integrated concept of caries causation. Studies of the in situ identification of bacteria with immunocytochemistry in relation to root caries will focus initially on a comprehensive identification of organisms in the 'advancing bacterial front' of dentin. This will be coupled with an analysis of the mineral content of areas of altered dentin which, according to our findings, appear to be due to the action of single types of organisms. This work may yield highly-significant new data on the cariogenicity of different plaque organisms. Later, this work will be expanded with a comparison of the composition of the plaque flora associated with intact and altered cementum or dentin.