2003 Fiscal Year Final Research Report Summary
Discoloration Mechanism of Dental Titanium and Titanium Alloys
| Project/Area Number |
13470420
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 |
ODA Yutaka Tokyo Dental College, Department of Dentistry, Professor, 歯学部, 教授 (00085838)
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| Co-Investigator(Kenkyū-buntansha) |
HATTORI Masayuki Tokyo Dental College, Department of Dentistry, Lecturer, 歯学部, 助手 (10307390)
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| Project Period (FY) |
2001 – 2003
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| Keywords | Titanium / Discoloration / Electrochemical / Corrosion / Denture cleaner / Titanium alloy |
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| Research Abstract |
In recent years, titanium prosthetics have been widely used in clinical dentistry. However, there are reports that titanium plates were discolored by some denture cleaner. This study investigated the cause. of discoloration by measuring the pH of denture cleaners and by surface analysis of discolored specimens using EPMA and XPS. Severe discoloration was observed with denture cleaners with a highly alkajine range. Discoloration was regarded as due to roughness caused by corrosion. The degree of discoloration depended on the thickness of the oxide film. The role of albumin on the corrosion behavior of titanium in a solution containing fluoride was elucidated. The corrosion of titanium in a solution containing fluoride was distinct, and that adding albumin to the solution containing fluoride suppressed corrosion. Fluorine was detected on the titanium surface immersed in the solution containing fluoride, and dissolution of the titanium was confirmed. The titanium immersed in a solution co
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ntaining both fluoride and albumin had an albumin film regardless of the albumin concentration. In addition, the amount of dissolved titanium from the titanium immersed in the solution was less than when the solution contained no albumin. It was suggested that the formation of adsorbed albumin films on in the passive film acted to not only protect the titanium from attack by the fluoride but also suppressed dissolution of the titanium-fluoride compounds.
Peroxide, which is produced by inflammatory cells, and fluoride prophylactic agents are two possible causes for the discoloration of titanium and titanium alloys. This study compared differences of the discoloration of several titanium alloys caused by peroxide and fluoride solutions. The rates of discoloration were different with the two solutions. The color difference was higher for Ti-Ni and Ti-Cu than for other alloys with H202. In contrast, these alloy showed only a slight change in the fluoride solution. This data implies that the rate of corrosion of titanium alloys is different for solutions containing peroxide than those containing fluoride. Less
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