| Project/Area Number |
13672044
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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 | Nagasaki University |
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Principal Investigator |
SHIRAISHI Takanobu Nagasaki Univ., Developmental & Reconstructive Medicine, Associate Professor, 大学院・医歯薬学総合研究科, 助教授 (10150468)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Yasuhiro Nagasaki Univ., Developmental & Reconstructive Medicine, Instructor, 大学院・医歯薬学総合研究科, 助手 (10217086)
HISATSUNE Kunihiro Nagasaki Univ., Developmental & Reconstructive Medicine, Professor, 大学院・医歯薬学総合研究科, 教授 (20037526)
TAKUMA Yasuko Nagasaki Univ., Faculty of Dentistry, Research Fellow, 歯学部, 教務職員 (60160074)
MIURA Eri nagasaki Univ., Developmental & Reconstructive Medicine, Instructor, 大学院・医歯薬学総合研究科, 助手 (70315258)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2002: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2001: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | dental alloy / Ag-Pd-Cu-Au alloy / alternative alloy / palladium / DSC / color / spectral reflectance / tarnish |
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| Research Abstract |
Experimental Pd-free Ag-Au-Pt-Cu alloys with various chemical compositions were prepared to substitute for traditional dental Ag-Pd-Cu-Au alloys. Liquidus and solidus temperatures were determined from DSC data. Spectrophotometric colorimetry was performed to investigate the optical properties and to quantify the tarnish resistance in the 0.1% Na_2S solution. Principal results obtained are as follows.
1. In the alloys with the same Au content, both liquidus and solidus temperatures lowered with increasing Cu content. Solidification temperature range became narrow with increasing Cu content.
2. In all the experimental alloys, spectral reflectance was high in the long-wavelength region and very low in the short-wavelength region due to the effective absorption of light.
3. In the alloys with the same Cu content, the absorption edge systematically moved towards longer wavelength direction with increasing Au content. Simultaneously, spectral reflectance in the long-wavelength region slightly decreased with increasing Au content. Owing to these systematic variations of spectral reflectance curves, chromaticity index b^* (yellow-blue) apparently increased, giving a gold tinge to the alloy.
4. In the alloys with the same Cu content of 15 at.% or 20 at.%, tarnish resistance of the alloys in the 0.1% Na_2S solution was markedly improved with Au content.
5. Among the three coordinates, L^*, a^*, b^*, in the CIELAB color space, decrease in L^*-value effectively affected the color change, ΔE^*, of the material in the tarnish test solution.
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