| Project/Area Number |
04671172
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Conservative dentistry
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| Research Institution | Kanagawa Dental College |
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Principal Investigator |
IWAMOTO Tsugio Kanagawa Dental Coll.Dept.of Restorative Dent.Professor, 歯学部, 教授 (90084722)
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| Co-Investigator(Kenkyū-buntansha) |
HANAOKA Koji Kanagawa Dental Coll.Dept.of Restorative Dent.Assis.Prof., 歯学部, 講師 (40198776)
TERANAKA Toshio Kanagawa Dental Coll.Dept.of Restorative Dent.Assoc.Prof., 歯学部, 助教授 (60104460)
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| Project Period (FY) |
1992 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1994: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1993: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1992: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Resin Composite / Fracture Toughness / Ring Specimen / Filler Content / Filler Shape / Filler Size / Frature Mechanics / グラスアイオノマーセメント / 破壊靱性 |
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| Research Abstract |
The objectives of this research project were 1) to determine the effect of water immersion period and thermal stress on fracture toughness (K_<IC>) of resin composite and light-cured glass ionomer cement using a ring specimen, 2) to evaluate the effect of filler shape, size and distribution on K_<IC>,3) to estimate the longevity of resin composit restorations using a fatigue test, and 4) to investigate the affecting factors on K_<IC> of resin composite using a ring specimen.
The results obtained were as follows :
1. The K_<IC> values of several commercial composites were decreased significantly from one day to one or three months stored in water. Thermal stressed composites showed a rapid decrease than the water immersed ones. The K_<IC> value of resin composite is significantly affected by prolonging water immersion period and increasing thermal stress.
2. The K_<IC> value of unfiled resin was significantly low (0.4 MPaROO<m>) , while the experimental resin composites with both spherical and crushed fillers showed the higher values ranged from 0.79 to 1.06 and from 0.96 to 1.30, respectively.
3. Resin composite with crushed filler always showed a significantly higher value of K_<IC> than those with corresponding size of spherical ones.
4. The resin composite containing spherical fillers rapidly generated the acoustic emission (AE) signal at the pop in, while gradual increase of AE signal was detected for the composite with crushed fillers.
5. The K_<IC> characteristics of resin composite was considerably affected by filler size.
6. The K_<IC> values of light-cured glass ionomer cements were ranged from 0.85 to 0.89 MPaROO<m>. These values were comparable to the micro-filled resin composites.
7. The fatigue strength reflected the retentive properties of the bonding site more accurately than the shear bond strength. The fatigue test should be utilized when estimating the durability of adhesive restorations in the oral cavity.
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