단계별 광중합 방식이 복합레진 수복물의 수축 응력과 변연 접합도에 미치는 영향
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- The purpose of this study was to investigate the effect of step-curing mode on polymerization shrinkage and contraction of composite resin restoration. Class I cavities were prepared on the extracted human premolars. The cavities were filled with Filtek Z-250TM(hybrid resin, 3M ESPE, USA) and Filtek flowTM(flowable resin, 3M ESPE, USA) and cured with one of the following irradiation modes; Halogen 40sec with continuous curing, LED 10 sec with continuous curing, and LED 13 sec with step-curing.
Contraction stress was measured with strain gauge which was connected to TML DataloggerTM(TDS-102, SOKKI, Japan) and resin-dentin interfaces were observed by scanning electron microscope.
The results of present study can be summarized as follows:
1. Composite resin 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 flowTM showed lower contraction stress than Filtek Z-250TM regardless of curing modes.
3. LED step-curing mode showed lowest contraction stress in Filtek Z-250TM compared with other curing modes(P<0.05).
4. LED step-curing mode showed lowest contraction stress in Filtek flowTM compared with other curing modes(P<0.05), but difference in contraction stress was not so greate as in Filtek Z-250TM.
5. Polymerization of composite resin by LED light with step-curing mode and halogen light with continuous mode resulted in better marginal sealing than LED light with continuous mode.
On the basis of above results, we think that LED light with step-curing mode will provide the reduction of polymerization contraction stress and the proper marginal seal of composite resin restoration.
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