1993 Fiscal Year Final Research Report Summary
Fatigue Crack Propagation in Composite Resins
| Project/Area Number |
04454469
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Conservative dentistry
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| Research Institution | Osaka University |
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Principal Investigator |
TSUCHITANI Yasuhiko Osaka Univ., Fac.of Dentisity, Professor, 歯学部, 教授 (40028709)
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| Co-Investigator(Kenkyū-buntansha) |
ITOTAGAWA Tokunori Osaka Univ., Fac.of Density, Instructor, 歯学部, 助手 (70232494)
TAKESHIGE Fumio Osaka Univ., Hospital Attached to the Fac.of Density, Instructor, 歯学部・附属病院, 助手 (60206969)
TORII Mitsuo Osaka Univ., Fac.of Dentisity, Associate Professor, 歯学部, 助教授 (30116066)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Composite resin / Fatigue crack / Fracture mechanics |
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| Research Abstract |
1.The Paris law (da/dN=C(DELTA K)^m) could be applied to the fatigue crack growth rate of the materials used in this study. Constant m was in the range of 24.3-32.2 for composite resins and 19.7-21.0 for unfilled resins. The DELTA K_<th> was in the range of 0.43-0.82 MPa・m^<1/2> for composite resins and 0.20-0.21MPa・m^<1/2> for unfilled resins. Constant m of dental composites was extremely higher than that of metal(m=2-7), but did not differ very much from each other. The fatigue crack growth rate of dental composites depended on DELTA K_<th> rather than constant m. 2.Microstructural examination of fatigue fracture surfaces by SEM indicated that the fatigue crack of dental composites propagated along the interface between inorganic filler and matrix, and that some organic fillers were penetrated with fatigue cracks.
3.Fatigue crack growth rate was more sensitive to degradation of composites by aging in water than transverse strength.
4.The fatigue resistance of composites measured as DELTA K_<th> decreased by aging in water. SEM observation showed that fatigue crack propagated in both matrix and filler-matrix interface after aging in water for three months.
These results indicated that that crack deflection and crack bridging by inorganic filler increased the fatigue resistance of composites, and that decrease of fatigue resistance by aging in water was caused by the degradation of resin matrix. From the present study, it was shown that the fatigue crack propagation test was an effective method to investigate toughening and degradation of dental composites.
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