| Project/Area Number |
12671852
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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 |
Conservative dentistry
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
SHINTANI Hideaki Hiroshima University, Faculty of Dentistry, Professor, 歯学部, 教授 (80034239)
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| Co-Investigator(Kenkyū-buntansha) |
URABE Hidenori Hiroshima University, Dental Hospital, Lecturer, 歯学部・附属病院, 講師 (10231185)
FUJITANI Morioki Hiroshima University, Faculty of Dentistry, Associate Professor, 歯学部, 助教授 (60190055)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2001: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2000: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | Er:YAG Laser / CO2 Laser / Adhesive resin / Dentin Bonding / Mechanism of Adhesion / Interface of Adhesion / Morphological Study / Analytical-chemical Study / CO2レーザー / 形態学研究 / Er:YAGレーザー |
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| Research Abstract |
This study was to investigate 1) the changes of surface characteristics of Er:YAG or CO2 lased dentin and 2) the adhesive properties of resinous materials to the lased dentin.
Labial surface of freshly extracted bovine tooth was ground to expose flat dentin. The dentin surfaces were then polished with 600-grid SiC paper and were irradiated by Er:YAG laser (60mJ/pulse, 10pps). The superficial layer of the lased dentin was morphologically examined by Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). The surface characteristics of lased dentin were chemically analyzed using X-ray Photoelectron Spectroscopy (XPS). In addition, the laser-irradiated cavity was restored with Mega Bond/AP-X according to the manufacturer's instructions, and the interfacial micro- and ultra-structures were observed under Scanning Electron Microscopy (SEM).
The AFM observation revealed that the structural defects such as micro cracks and stratified structures were formed. By the TEM observat
… More
ions, the amorphous matrix substances of 10-15mm thickness, which consisted of denatured dentin collagen, were superficially observed. The analysis of XPS wide-scan spectrum of lased dentin surface showed the intensity of both CIs and NIs peaks obviously decreased. The SEM examination of resin-dentin interface revealed that the degenerated layer of 10-12mm thickness was observed beneath the hybrid layer.
Early bond strength and durability of adhesion of the commercial adhesives to the lased dentin were significantly lower than those to the rotary cut dentin in micro-tensile bond test. This might be caused by the concentration of stress to those structural defects, by the inhibition of resin-impregnation due to the denatured layer, or by the deterioration of mechanical properties of the hybrid layer and the lased dentin itself.
It was suggested that both the structural defects and the denatured layer affect the adhesive properties of resinous materials to the Er:YAG laser-irradiated dentin. Less
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