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KMID : 0358920050320020312
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Journal of the Korean Academy of Pedodontics
2005 Volume.32 No. 2 p.312 ~ p.320
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INFLUENCE OF IRRADIATION MODES ON THE MICROHARDNESS AND THE POLYMERIZATION CONTRACTION OF COMPOSITE RESIN POLYMERIZED WITH LED CURING UNIT
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Park In-Ho
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 polymerization contraction and the micro hardness of composite resin(Supreme？, Filtek Flow？, 3M-ESPE, USA) according to irradiation modes of LED curing unit(Elipar Freelight？, 3M-ESPE, USA).
The strain guage method was used for determination of polymerization contraction. Sample were divided by 6 groups according to curing modes and filling method.
Group A: Supreme？, Filtek Flow？ lining, 10seconds curing, Group B: Supreme？, Filtek Flow？ lining, 15seconds curing, Group C: Supreme？, Filtek Flow？ lining, 15seconds soft start curing, Group D: Supreme？ only, 10seconds curing, Group E: Supreme？ only, 15seconds curing, Group F: Supreme？ only, 15seconds soft start curing
Preparations of acrylic molds were followed by filling and curing. Strain guage attached to each sample were connected to a strain meter. Measurements were recorded at each second for the total of 10 minutes including the periods of light application. And micro hardness of each group after 24hours from light irradiation were measured.
Obtained data were analyzed statistically using Repeated measures ANOVA and Tukey test.
The results of the present study are as follows:
1. In flow able resin liner group, soft start curing group was not found decrease of polymerization contraction. But, In Supreme only filling group, the lowest polymerization contraction was found in soft start curing group.
2. 10 seconds curing group showed statistically significant reduction of polymerization contraction compared with 15 seconds curing group(p<0.05).
3. The micro hardness values of each group not revealed significant difference(p>0.05). But, lower surface micro hardness was not reached 80% of upper surface micro hardness.
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KEYWORD
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LED curing unit, Polymerization contraction, Microhardness
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