2007 Fiscal Year Final Research Report Summary
Study on bacterial ecology and structural permeability within dental plaque using a quantitative method for mapping the distribution pattern of plaque bacteria
| Project/Area Number |
17592192
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Social dentistry
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| Research Institution | Aichi Gakuin University |
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Principal Investigator |
KATO Kazuo Aichi Gakuin University, School of Dentistry, Associate Professor (60183266)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Depth-specific analysis / Dental plaque structure / Bacterial ecology / Mutans Streptococci / Probiotic / Fluoride compound |
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| Research Abstract |
(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
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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
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