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- Effects of the color components of light-cured composite resin before and after polymerization on degree of conversion and flexural strength
- Ji-A Yoo, Byeong-Hoon Cho
- J Korean Acad Conserv Dent 2011;36(4):324-335. Published online July 31, 2011
- DOI: https://doi.org/10.5395/JKACD.2011.36.4.324
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Abstract
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ePub Objectives This study investigated the effects of the color components of light-cured composite resin before and after polymerization on degree of conversion (DC) and biaxial flexural strength (FS).
Materials and Methods Four enamel shades (A1, A2, A3, A4) and two dentin shades (A2O, A3O) of Premisa (Kerr Co.) and Denfil (Vericom Co.) were evaluated on their CIE L*, a*, b* color components using the spectrophotometer before curing, after curing and at 7 day. The DC of same specimens were measured with Near-infrared spectrometer (Nexus, Thermo Nicolet Co.) at 2 hr after cure and at 7 day. Finally, the FS was obtained after all the other measurements were completed at 7 day. The correlations between each color component and DC and FS were evaluated.
Results The light-curing of composite resin resulted in color changes of Premisa in red-blue direction and Denfil in green-blue direction. The DC and FS were affected by product, time and shade (3-way ANOVA,
p < 0.05) and product and shade (2-way ANOVA,p < 0.05), respectively. Premisa only showed a significant correlation between the DC and CIE a* component - before and after polymerization (Pearson product moment correlation,p < 0.05). The FS of Premisa showed significant negative correlations with CIE a* and CIE b* components.Conclusions The DC and FS of the light-curing composite resin were affected by the color components of the material before and after polymerization.
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Original Article
- Comparative enamel bond strength between light- and dual-cured composites bonded by self-etching adhesives
- Young-Gon Cho, Sang-Hoon Yoo
- J Korean Acad Conserv Dent 2007;32(1):1-8. Published online January 31, 2007
- DOI: https://doi.org/10.5395/JKACD.2007.32.1.001
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Abstract
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This study compared the microshear bond strength (µSBS) of light-cured and dual-cured composites to enamel bonded with three self-etching adhesives. Crown segments of extracted human molars were cut mesiodistally, and 1 mm thickness of specimen was made. They were assigned to three groups by used adhesives: Xeno group (Xeno III), Adper group (Adper Prompt L-Pop), and AQ group (AQ Bond). Each adhesive was applied to cut enamel surface as per manufacturer's instruction. Light-cured (Filtek Z 250) or dual-cured composite (Luxacore) was bonded to enamel of each specimen using Tygon tube.
After storage in distilled water for 24 hours, the bonded specimens were subjected to µSBS testing with a crosshead speed of 1 mm/minute. The mean µSBS (n = 20 for each group) was statistically compared using two-way ANOVA, Tukey HSD, and t test at the 0.05 probability level. The results of this study were as follows;
1. The µSBS of light-cured composite was significantly higher than that of dual-cured composite when same adhesive was applied to enamel.
2. For Z 250, the µSBS of AQ group (9.95 ± 2.51 MPa) to enamel was significantly higher than that of Adper goup (6.74 ± 1.80 MPa), but not significantly different with Xeno group (7.73 ± 2.01 MPa).
3. For Luxacore, the µSBS of Xeno group (5.19 ± 1.32 MPa) to enamel was significantly higher than that of Adper goup (3.41 ± 1.19 MPa), but not significantly different with AQ group (4.50 ± 0.96 MPa).
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