Study on bacterial ecology and structural permeability within dental plaque using a quantitative method for mapping the distribution pattern of plaque bacteria

(1)通过从牙菌斑最外层到最内层的变形链球菌深度特异性分析，评价SnF_2凝胶处理对牙菌斑的体内抗菌效果。变形链球菌阳性分数的模式在受试者之间变化很大。虽然处理后含有变形链球菌的菌斑层频率更高，表明处理使其在菌斑中的栖息地明显变宽，但处理后菌斑层的体积明显降低。结果表明，SnF_2凝胶的应用确实增加了牙菌斑的孔隙度，为蛀牙细菌提供了更大的栖息地，特别是在更深的区域。(2)食用含罗伊氏乳杆菌和不含任何甜味剂的两种酸奶产品均可显著降低唾液中变形链球菌的检出率，而含木糖醇代替蔗糖的酸奶产品则没有显著效果。任何酸奶产品的消费……都不能与sobrinus的显著减少联系起来。然而，安慰剂对照试验表明，食用含有罗伊氏乳杆菌的酸奶并不能显著减少菌斑内变形链球菌的栖息地。(3)采用基于16S核糖体RNA基因的种特异性巢式两步PCR扩增技术，建立快速灵敏的人牙菌斑龋菌检测方法。使用一套细菌16S核糖体RNA基因通用引物（用于第一次PCR），以及根据16S rRNA基因序列比对设计的两套突变链球菌或sobrinus特异性PCR引物（用于第二次PCR）。来自8名志愿者的菌斑样本被用于巢式PCR，巢式PCR比使用特定引物集的直接PCR更敏感。(4)显微放射观察显示NaF和MFP的耐酸性有很大差异。NaF处理的牙釉质仅在表面表现出耐酸性。而MFP处理后的牙釉质具有厚而深的耐酸层。因此NaF不能渗透到牙釉质中，而MFP渗透得更深。结果表明，NaF和MFP在酸性条件下的耐酸性投资上有很好的对比。少

(1) The antimicrobial effect of SnF_2 gel treatment on dental plaque in vivo was evaluated, using a depth-specific analysis of Streptococcus mutans from the outermost to the innermost plaque. The patterns of positive fractions for S. mutans were highly varied among the subjects. Although frequencies of plaque layer containing S. mutans were higher after the treatment, indicating that the treatment made their habitat in plaque significantly wider, volume of plaque layers were significant lower after the treatment. The results suggested that the application of SnF_2 gel might indeed increase the porosity of plaque, creating a larger habitat for cariogenic bacteria particularly in deeper regions.(2) Consuming both yogurt products containing L. reuteri with sucrose and without either sweetener significantly reduced the detection rates of S. mutans in saliva, although the product including xylitol instead of sucrose couldn't produce significant results. The consumption of any yogurt product … More s could not be linked to any significant reductions of S. sobrinus. However, placebo-controlled trial demonstrated that consuming yogurt with L. reuteri could not significantly reduce the habitat for mutans streptococci within plaque in vivo.(3) Species-specific nested, two-step PCR amplification based upon 16S ribosomal RNA genes was employed to develop the rapid and sensitive detection method for cariogenic bacteria in human plaque. A set of PCR primers universal for bacterial 16S ribosomal RNA gene (for the first PCR), and two sets of PCR primers specific for either S. mutans or S. sobrinus designed from the alignment of the 16S rRNA gene sequences (for the second PCR) were used. Plaque samples from 8 volunteers were used for the nested PCR, and the nested PCR was shown to be more sensitive rather than a direct PCR using specific primer sets.(4)Observations of microradiography revealed great differences in acid resistance between NaF and MFP. NaF treated enamel showed acid resistant at only superficial area. However MFP treated enamel has thick and deep acid resistant layer. Therefore, NaF could not penetrate into the enamel while MFP penetrated deeper. The results showed that NaF and MFP made an interesting contrast at investment of acid resistance on acidic condition. Less