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KMID : 0358920060330020221
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Journal of the Korean Academy of Pedodontics
2006 Volume.33 No. 2 p.221 ~ p.232
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EFFECT OF STEP CURING ON THE CONTRACTION STRESS AND MARGINAL ADAPTATION OF RESIN RESTORATION
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Park Jong-Whi
Lee Nan-Young
Lee Sang-Ho
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Abstract
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The purpose of this study was to inverstigate the effect of step-curing mode on polymerization shrinkage and contraction of composite resion restoration. Class I cavities were prepared on the extracted human premolars. The cavities were filled with Filtek Z-250™(hybrid resin, 3M ESPE, USA) and Filtek flow™(flowable resin, 3M ESPE, USA) and cured with one of the following irradiation modes; Halogen 40sec with continuous curing, LED 10sec with continuous curing, and LED 13sec with step-curing.
Contraction stress was measured with strain gauge which was connected to TML Datalogger™(TDS-102, SOKKI, Japan) and resion-dentin interfaces were observed by scanning electron microscope.
The results of present study can be summarized as follows:
1. Composite resion restoration showed transient expansion just after irradiation of curing light. Contraction stress was increased rapidly at the early phase of polymerization and reduced slowly as time elapsed(P<0.05).
2. Filtek flow™ showed lower contraction stress than Filtek Z-250™ regardless of curing modes.
3. LED step-curing mode showed lowest contraction stress in Filtek Z-250™ compared with other curing modes(P<0.05).
4. LED step-curing mode showed lowest contraction stress in Filtek flow™ compared with other curing modes(P<0.05), but difference in contraction stress was not go greate as in Filtek Z-250™.
5. Polymerization of composite resion by LED light with step-curing mode and halogen light with continuous mode resulted in better marginal sealing than LED light with continuous mode.
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KEYWORD
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Light curing, Polymerization shrinkage, Contraction stress, Step-curing, LED
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