| Project/Area Number |
17592043
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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 |
補綴理工系歯学
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| Research Institution | Tokyo Dental College |
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Principal Investigator |
KAWADA Eiji Tokyo Dental College, 歯学部, Professor (40147260)
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| Co-Investigator(Kenkyū-buntansha) |
HOSOYA Yumiko Nagasaki University, Scholl of Dentistry, 准教授 (80112803)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥2,910,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | nano inentatio / bleaching / vital tooth / morphology / hydrogen peroxide / enamel / cross-sectional structure / 硬さ / 歯学 / 光沢 |
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| Research Abstract |
Carbamide peroxide and hydrogen peroxide are used as the main agent in vital tooth bleaching. In this study, bovine enamel was immersed in different concentrations of peroxide over differing periods of time to clarify the influence of peroxide treatment. Its influence on cross-sectional morphology and mechanical properties was investigated.
Bovine enamel surfaces, from which coronal cementum was removed, were covered with nail varnish, except for a 3x5-mm window on the labial surface. Specimens were then immersed in 10% or 30% carbamide peroxide (CP) or hydrogen peroxide (HP) for 30 or 180 min (n=5, each condition). The specimens were then embedded in epoxy resin and cut at an angle perpendicular to the tooth axis 7 mm from the incisal edge of the tooth. Sectional enamel was finally polished with a 0.05-gm alumina suspension. Nanohardness was determined by using a nanoindentation system. Observation was carried out under scanning electron microscopy. The nanohardness of the enamel treated with either peroxide decreased at 2μm below the outermost enamel surface, but no decrease was observed at 50 tm. Higher concentrations of peroxides caused erosion to a depth of 5μm below the outermost surface, which was deeper than that with a low concentration of peroxide.
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