1997 Fiscal Year Final Research Report Summary
The caries preventive effects of laser irradiation on occlusal pits and fissures
| Project/Area Number |
07672225
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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 |
矯正・小児・社会系歯学
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| Research Institution | Nagasaki University |
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Principal Investigator |
TAKAGI Okiuji Nagasaki Univ.School of Dentistry, Dept.of Preventive Dentistry, Professor, 歯学部, 教授 (80005090)
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| Co-Investigator(Kenkyū-buntansha) |
INABA Daisuke Iwate Medical Univ.School of Dentistry Dept.of Preventive Dentistry, Associate P, 歯学部, 助教授 (90146085)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Laser / Cariostatic effects / Mineral distribution / Intraoral study / Microradiography / pit and fissure / Enamel |
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| Research Abstract |
Laser irradiation has been reported to provide caries preventive effects by improving acid resistance of enamel surfaces. The acid resistance has been examined mainly by a Ca releasing rate from enamel in an acidic solutions. However, this method is not proper because it can not simulate a process of caries formation. Since interaction between enamel and plaque is important in caries research, caries formation test was carried out by exposure of lased enamel to an acidic gel system previously. As a result, no significant differences of mineral parameters (the lesion depth Id and mineral loss valucs DELTAZ) were not detected between lased and unlased samples. In this study, mineral changes in lased enamel by exposing samples to oral cavities. Human enamel blocks were used for the experiment. To promote plaque deposition and to simulate occlusal fissures, an U-shaped groove was formed in the central part of enamel surfaces. The samples were immersed in a 0.1 M lactic acid gel to produce artificial early caries-like lesions, and were irradiated with Q-switched Nd : YAG laser at a total energy dose of 100 J/cm2. The lased or unlased enamel samples were mounted on upper first molar of lO adults for 1 month. During the experimental period, dental plaque was maintained without brushing. Mineral distributions of the samples are under assessment by a transversal microradiography (TMR) and computer-assisted videodensitometry (CAV). The microradiograms of the samples show no visual differences between lased and unlased samples. In addition, any sign of remineralization is not observed is all the samples. In conclusion, it was suggested that caries susceptibility of enamel may not be changed by laser irradiation, and that intra oral study is essential to evaluate caries preventive effects of laser irradiation.
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