HIGH-SPEED DETECTION METHOD OF METALLIC ELEMENTS OF DENTAL RESTORATION FROM ALLERGY SUSPECTED PATIENTS BY X-RAY FLUORESCENCE ANALYSIS

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 12557166
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 展開研究
• Research Field: 補綴理工系歯学
• Research Institution: NIIGATA UNIVERSITY
• Principal Investigator: MIYAKAWA Osamu Graduate School of Medical and Dental Sciences, NIIGATA UNIVERSITY, Professor, 大学院・医歯学総合研究科, 教授 (40018429)
• Co-Investigator(Kenkyū-buntansha): HASHIMOTO Akihiko Dental Hospital, NIIGATA UNIVERSITY, Lecturer, 歯学部・附属病院, 講師 (20283020) ; OKAWA Seigo Graduate School of Medical and Dental Sciences, NIIGATA UNIVERSITY, Assistant, 大学院・医歯学総合研究科, 助手 (80143791) ; WATANABE Kouichi Graduate School of Medical and Dental Sciences, NIIGATA UNIVERSITY, Associate Professor, 大学院・医歯学総合研究科, 助教授 (20018766) ; MURASE Jun Horiba Cooperation, Research Center, Team Leader, 分析センター, チームリーダー(研究職)
• Project Period (FY): 2000 – 2001
• Keywords: metal allergy / X-ray fluorescence analysis / sample collection / high-speed detection / element analysis

Research Abstract

For diagnosis and treatment of metal allergy, it is essential to know the metallic elements composing the restorations in a suspected patient. This research aimed to confirm the hypothesis that microscopic X-ray fluorescence analysis can quickly provide effective information on the metallic elements, in spite of a very small amount of sample collected from the patient's mouth. The sample was collected by rubbing the restorations with the sharp corner of a folded lapping film. The sample like a spot at the corner was analyzed by a microscopic X-ray fluorescence equipment (XGT-2700, Horiba, Japan), which generates X-ray beam of 0.1 mm in diameter. Routine analysis took 8 minutes at most, including collection of the sample from the patient's mouth, charge of the sample, detection of the characteristic X-rays, and final display of the result. Based on the calibration line that was obtained by measuring X-ray intensity from standard gold films, the amount of gold sample on the film was estimated to be several tens nanogram. In the case of such a faint sample, the sensitivity for each element decreases with the increase of its characteristic X-ray energy because of the lack of sufficient information depth. To correct this intensity abnormality, the lapping film was covered with a plastic film before measurement. For typical dental alloys, main components were evaluated within a few percents deviation from the values indicated by manufacture. Furthermore, additive elements of 0.5 % or more, such as zinc, could be detected in high reliability. From these results, it is concluded that the high-speed detection method of metallic elements of dental restoration is very useful for diagnosis metal allergy.