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KMID : 0358920050320020332
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Journal of the Korean Academy of Pedodontics
2005 Volume.32 No. 2 p.332 ~ p.343
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EFFECT OF SOFT-START LIGHT CURING ON THE POLYMERIZATION AND THE CONTRACTION STRESS OF COMPOSITE RESIN
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Wee You-Min
Oh You-Hyang
Lee Nan-Young
Lee Chang-Seep
Lee Sang-Ho
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Abstract
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The purpose of this study was to evaluate the influence of soft-start light curing on contraction stress and hardness of composite resin.
Composite resin mold was cured using the one-step continuous curing method with three difference light sources; conventional halogen light curing for 40 seconds at 400 mw/㎠, plasma arc light curing for 6 seconds at 1300 mW/㎠ and LED light curing for 10 seconds at 700 mW/㎠. For the soft-start curing method 2 seconds light exposure at 650 mW/㎠ followed by 3 seconds at 1300 mW/㎠ and exponential increase with 5 seconds followed by 10 seconds at 700 mW/㎠ were used.
Contraction stress was measured using strain gauge method and Vickers hardness was measured 24 hours after polymerization at the top and bottom of specimens.
Resin-acrylic interfaces were observed using a scanning electron micro scope(SEM).
The results of present study can be summarized as follows:
1. Contraction stresses at 10 min after polymerization were significantly reduced with the soft-start curing both in plasma and LED light sources(P<0.05).
2. Plasma light curing with soft-start resulted in not only the lowest contraction stress, but also the lowest hardness (P<0.05).
3. LED light curing with soft-start showed lower contraction stress than the one-step continuous halogen and LED light curing(P<0.05).
4. Micro hardness of specimens cured by LED light with soft-start was equivalent to that of cured by the one-step continuous halogen and LED light(P>0.05).
5. Curing by LED light with soft-start and conventional halogen light resulted in better marginal sealing than plasma light and one-step LED light curing.
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KEYWORD
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Soft-start light curing, Contraction stress, Microhardness
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