1998 Fiscal Year Final Research Report Summary
Curing method for reducing polymerization contraction stress of light-curing resin composite
| Project/Area Number |
09671947
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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 | Tokyo Medical and Dental University |
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Principal Investigator |
YOSHIKAWA Takako Tokyo Medical and Dental University, 歯学部, 助手 (00182733)
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| Co-Investigator(Kenkyū-buntansha) |
MORIGAMI Makoto Tokyo Medical and Dental University, 歯学部, 助手 (30292973)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Light-cured resin composite / Slow-start curing method / Polymerization controaction stress / Palymerization behavior / marginal sealing / Cavity wall adaptation / Environmental SEM / Incremental filling technique |
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| Research Abstract |
Light-cured resin composites are now widely used in daily clinical practice because of their esthetic advantages, ease of use, good bonding to tooth structure, and improved mechanical properties. However, light-cured resin composites are usually polymerized from the resin surface near a light source, which causes polymerization contraction of the resin composite towards the light. This shrinkage creates more gaps between the resin and cavity wall/floor than self-cured resin composites.
This projects was to evaluate the effect of the light wring method on the marginal sealing and cavity wall adaptation on resin composite restorations with different C-factor shapes and also to evaluate the effect of incremental filling technique on resin micro-bond strength to Class I dentin-cavity floors. Moreover, environmental SEM observation was carried out to evaluate on resin-tooth interface using two light curing method.
It was concluded that incremental filling technique did not improve dentin micro-bond strength to cavity floor. On the other hand, slow-start curing method ; 270 mW/cm^2 10 s + 5 s (interval) + 600 mW/cm^2 50 s reduce the polymerization contraction stress, and tended to improve marginal sealing and resin composite adaptation to the cavity wall regardless of bonding system and C-factor. Ordinary curing method ; 600 mW/cm^2 60 s resulted in poor marginal sealing and wall adaptation. Environmental SEM observation showed that the slow-start curing method improved resin composite adaptation to the cavity wall and this curing method was effective to the cavities both with and without enamel margin.
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