1987 Fiscal Year Final Research Report Summary
Bacteriological Study for Prevention of Recurrent Caries
| Project/Area Number |
60440088
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Conservative dentistry
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| Research Institution | Niigata University |
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Principal Investigator |
IWAKU Masaaki Niigata University, 歯学部, 教授 (70013927)
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| Co-Investigator(Kenkyū-buntansha) |
ARAI Hideaki Niigata University, 歯学部, 助手 (00175952)
KOTA Kohichi Niigata University, 歯学部, 助教授 (90018755)
HOSHINO Etsuro Niigata University, 歯学部, 教授 (90124619)
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| Project Period (FY) |
1985 – 1987
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| Keywords | Recurrent caries / Anaerobes / Metronidazole / α-TCP |
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| Research Abstract |
Bacteriological Study for Prevention of Recurrent Caries This study was projected to develop the most effective clinical method for preventing recurrent caries by using bactericidal material against bacteria in human carious dentin. It was clarified by Hoshino that the majority of microorganisms isolated from both shallow and deep layers of dentinal lesions are obligate anaerobes, which suggests that autimicrobial treatment directed specifically against anaerobes may be effective in preventing complications. And, it has been well known that metronidazole(MN) has a wide spectrum of bactericidal action against obligate anaerobes.
Bactericidal efficacy of MN against bacteria in human carious dentin was clarified as follows:
1. Bacterial recovery from human carious dentin obtained from patients was measured on BHI-Blood agar plates containing MN(10<mu>g/ml) and on those lacking MN, and the addition of MN caused more than 99% reduction of bacterial recovery.
2. Overwhelming majority of bacteria in carious dentin of freshly extracted human teeth was not recovered when the lesions were covered with <alpha>-Tricalcium Phosphate <alpha>-TCP) cement containing 5% MN for 1-3 days, whereas more than 10^3 bacteria(CFU) were obtained when the lesions were covered with <alpha>-TCP cement containing no MN.
3. No any bacteria were recovered from the samples of dentinal lesions which hab been covered by <alpha>-TCP cement containing MN in situ for 1 day, 28 days and/or 1 year ana/or 2 years in vivo. The bactericidal efficacy of MN in situ is clearly demonstrated, suggesting that topical application of MN is effective in caries treatment to deisinfect bacteria which remained accidentally in the smear layer and under restorations or intentionally in the deep layers of acute dentin caries of the child's permanent molar just after eruption to avoid pulp exposure, or invade newly from the tooth surfaces.
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