| Project/Area Number |
63045008
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | University-to-University Cooperative Research |
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| Research Institution | Tokyo Medical and Dental University (1989-1990)
Mining College, Akita University (1988) |
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Principal Investigator |
MIYAIRI Hiroo Tokyo Med. Dent. Univ., Inst. Med. Dent. Engng, Professor, 医用器材研究所, 教授 (50013892)
HONDA Sakuro (1988) Mining College, Akita University, 鉱山学部, 教授 (50006631)
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| Co-Investigator(Kenkyū-buntansha) |
魏 燕 北京医科大学, 口腔医学研究所, 助理研究員
鄭 剛 北京医科大学, 口腔医学研究所, 工程師
王 光和 北京医科大学, 口腔医学院, 院長
徐 恒昌 北京医科大学, 口腔医学研究所, 教授
FUKUDA Hideaki Tokyo Med. Dent. Univ., Inst. Med. Dent. Engng, Assistant, 医用器材研究所, 助手 (50014163)
NAGAI Masahiro Tokyo Med. Dent. Univ., Inst. Med. Dent. Engng, Assistant, 医用器材研究所, 助手 (10013971)
TAKAKUDA Kazuo Tokyo Med. Dent. Univ., Inst. Med. Dent. Engng, Assoc. Professor, 医用器材研究所, 助教授 (70108223)
UEI Ian Beijing Med. Unvi., School of Stomatology, Assistant
ZHENG Gang Beijing Med. Univ., School of Stomatology, Engineer
WANG Khung Beijing Med. Univ., School of Stomatology, Professor
XU engchang Beijing Med. Univ., School of Stomatology, Professor
RATANASTHIEN チェンマイ大学, 理学部, 助教授
YAMAMOTO Masatsugu Mining College, Akita University, 鉱山学部, 講師 (80191443)
KITA Itsuro Mining College, Akita University, 鉱山学部, 助教授 (10143075)
TAKASHIMA Isao Mining College, Akita University, 鉱山学部, 助教授 (50163192)
AKIBAYASHI Satoshi Mining College, Akita University, 鉱山学部, 助教授 (90006669)
RATANASTHIEN Benjavun Faculty of Science, Chiang Mai University
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| Project Period (FY) |
1988 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 1990: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1989: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1988: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Dental Adhesive Materials / Composite Resins / Resin Cements / Strength of Adhesives / Wear / Thailand / Geothermal resources / Heat source / Reservoir engineering / Age dating / Isotope geochemistry / 土壌ガス |
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| Research Abstract |
We study here the durability of dental adhesive materials. The evaluation of durability is so important that it includes not only the degradation of adhesive strength but also the marginal leakage, degradation of materials themselves and the wear properties.
1. Dental composite resins are the most popular dental adhesive materials. The wear properties are one of the most serious concerns of many clinicians. The mechanism of wear phenomena includes the wear of the matrix resins themseleves and the falling off of fillers after the degradation of matrix-filler interfaces. In coming decades, the improvement of these materials will be focused on the strengthening of the matrix-filler interfaces because the strengthening of resins the organic materials being seemed so difficult. Thus we investigate the degradation of matrix-filler interfaces here. First we improve the wear testing machine which simulates the wear mechanism in the oral environment, by the applications of elastomer materials be
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tween the experimental resin specimens and opposite steel cylinders. It was verified that the wears similar to those in oral environment can be realized by this machine.
2. In order to improve the in vitro simulation of the degradation mechanism in the oral environment, we further attempt the repeated application of mechanical stresses to the resin specimens, prior to the wear testings. The materials choosed are the micro-filler type and those for resin-inlay. Then we found that so high stresses as one third of ultimates strength and so many times as 1,000,000 do not induce significant degradation of wear properties. The SEM observation also reveal no significant differences on the wear surfaces. It is concluded that recent commercial materials as tested are so improved that no significant degradation will be observed after the dry fatigue testings. The degradation may be accelerated by the wet fatigue testings.
3. The durability of adhesive strength is the most important concerns for adhesive resin cement. Hence next we develop the load application apparatus for the adhesive specimens held in water. The influence of mechanical stresses and environmental effects are examined for the composite resin type resin cements. Then it is found that the simultaneous applications of the mechanical and environmental effect is essential to the acceleration of the adhesive strength degradation. The sole application of mechanical stresses without aqueous environment or the holding of specimens in aqueous environment without mechanical stresses do not induce significant degradation in specimens. Further, the tensile stresses are found to be more effective than the shear stresses for the acceleration of the degradation.
4. Marginal leakages also are important problems for dental resin cements. So we try to install the specimens for monitoring crack extensions to the above mentioned load application apparatus. We examined the two distinct types of adhesives and compare the results, the one is composite resin type whereas the other do not contain any fillers. The slow crack extension was observed in the soft adhesives. On the other hand, brittle fracture is observed in rigid adhesives. Less
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