Journal of the Korean Academy of Pediatric Dentistry 2005;32(2):312-320.
Published online May 31, 2005.
NFLUENCE OF IRRADIATION MODES ON THE MICROHARDNESS AND THE POLYMERIZATION CONTRACTION OF COMPOSITE RESIN POLYMERIZED WITH LED CURING UNIT
 
Correspondence:  , 
Abstract
The purpose of this study was to evaluate the polymerization contraction and the microhardness of compostie 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 strainmeter. Measurements were recorded at each second for the total of 10 minutes including the periods of light application. And microhardness 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 flowable resin liner group, soft start curing group was not found decrease of polymerization contraction. But, In Supreme only filling group, the lowest polymeriation 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 microhardness values of each group not revealed significant difference(p>0.05). But, lower surface microhardness was not reached 80% of upper surface microhardness.
Key Words: LED curing unit, Polymerization contraction, Microhardness


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