1991 Fiscal Year Final Research Report Summary
Annual changes in the level of fluorine in the third molar of Japanese during 1900 - 1970
| Project/Area Number |
01480488
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
小児・社会系歯学
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| Research Institution | National Institute of Health |
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Principal Investigator |
HINOIDE Moriyo National Institute of Health Oral Science Chief, 口腔科学部・生化学室々長 (60072906)
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| Co-Investigator(Kenkyū-buntansha) |
IMAI Susumu NIH Oral Science Chief researcher, 口腔科学部, 主任研究官 (80072958)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Tooth / Surface enamel / Fluorine level / Annual change / 1990 - 1970 |
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| Research Abstract |
In order to get the basic data concerning the amount of fluorine(F) ingested by Japanese, we examined the F content in the enamel surface of the third molar, and also examined annual changes in the F content.
1. We first developed the method for micro-determination of F using Teflon micro-diffusion vessel, and compared this method with direct method reported by McCann. Good accordance of F level in enamel was observed, but higher value of F level in dentin was obtained by micro-diffusion method. Therefore, F level in enamel and dentin were determined by direct method and micro-diffusion method, respectively.
2. Secondary, we examined the relationship between subject age at extraction of tooth and F level in enamel and dentin. It was observed that F content increased with age. The F level in enamel, however, did not increase because of abrasion of the tooth surface. Tooth sample as an index substance was limited to the tooth of extraction age at 20-29.
3. Thirdly, we determined the F level in the first and second layer of tooth enamel. Minute examination of F level in the first enamel layer was impossible because of large variation. Annual changes in F content in the second enamel layer was evident. The F content in this layer was generally high before the World War II, increased in the War, and then decreased gradually after the War. It could not be predicted during this research project that the F content in this layer might show decrease or no fluctuation in the future. Further continued examination is necessary to clear it.
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