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

(1)通过对变形链球菌菌斑从外到内的深度特异性分析，评价了SNF2凝胶处理对牙菌斑的体内抑菌效果。变形链球菌的阳性部分在不同的受试者中有很大的不同。虽然治疗后菌斑层中含有变形链球菌的频率增加，表明治疗使其在菌斑中的栖息地明显变宽，但治疗后菌斑层的体积明显降低。结果表明，SNF2凝胶的应用确实可能增加菌斑的孔隙率，为致龋菌创造更大的栖息地，特别是在更深的地区。(2)无论是含路氏乳杆菌的酸奶产品加蔗糖还是不加任何甜味剂，都能显著降低唾液中变形链球菌的检出率，尽管含木糖醇的酸奶产品不能产生显著的效果。消费任何酸奶产品…更多的S不能与远缘链球菌的任何显著减少联系在一起。然而，安慰剂对照试验表明，饮用含有路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)基于16S核糖体RNA基因的物种特异性套式两步聚合酶链式反应技术，建立了快速、灵敏的检测人菌斑中致龋菌的方法。使用一组细菌16S核糖体RNA基因通用的聚合酶链式反应(第一次)和根据16S rRNA基因序列比对设计的两套针对变形链球菌和远缘链霉菌的聚合酶链式反应(第二次聚合酶链式反应)。用8例健康志愿者的菌斑标本进行套式聚合酶链式反应，结果表明套式聚合酶链式反应比直接聚合酶链式反应更敏感。(4)显微放射学观察显示NaF和MFP的耐酸性有很大差异。氟化钠处理后的牙釉质仅在表面表现出耐酸性。然而，经MFP处理的牙釉质具有较厚的耐酸层。因此，氟化钠不能渗透到牙釉质中，而MFP渗透得更深。结果表明，在酸性条件下，NaF和MFP在耐酸性能方面有很好的对比。较少

(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