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Operative Dentistry, 2010, 35-6, 605-609
Laboratory Research
Effect of Accelerated Aging on the Color and Opacity of Resin Cements M Ghavam • M Amani-Tehran • M Saffarpour
Clinical Relevance While the studied cements behaved acceptably according to the color change index (∆E), they functioned differently in regards to opacity, especially the self-cure ones.
SUMMARY Statement of the Problem: The color stability of resin cements plays a major role in the esthetic performance of porcelain laminate veneers. Some dual-polymerizable resin cements used to bond porcelain laminates were shown to undergo color changes during service. Some recently produced cements are described as being color stable, but scientific data are not available. Purpose: The current study evaluated the effect of accelerated aging on the color and opacity of resin cements. The hypothesis was that the *Maryam Ghavam, DDS, MSc, associate professor, Department of Operative Dentistry, School of Dentistry, Tehran University of Medical Sciences, Dental Research Center, Tehran, Iran Mohammad Amani-Tehran, PhD, associate professor, Color Technology, Textile Engineering Department, Amirkabir University of Technology, Tehran, Iran Mahshid Saffarpour, assistant professor, Department of Operative Dentistry, School of Dentistry, Ghazvin University of Medical Sciences School of Dentistry, Qazvin, Iran *Reprint request: 9, Third West St, Seoul Blvd, Vanak Ave, Tehran, 19959, Iran; e-mail:
[email protected] DOI: 10.2341/09-161-L
auto-polymerizing cements would show less color and opacity stability. Materials and Methods: Forty (0.7 x 18 mm) feldspathic porcelain disks were prepared and divided into four equal groups. The resin cements were bonded to the disks by application of an identical load of 2.5 kilograms, and they were polymerized according to the manufacturer’s instructions. The groups were: Variolink Veneer (light-polymerizing), Variolink II (lightpolymerizing), Variolink II (dual-polymerizing) and Multilink (auto-polymerizing). A spectrophotometer was used to measure the following color parameters in the CIE L*a*b* color space on a black and white background: ∆a*, ∆b*, ∆L*, ∆C, ∆H, ∆E and ∆CR (contrast ratio). The measurements were performed before and after aging. Paired t- and one-way ANOVA tests were α=.05). used to analyze the data (α Results: None of the groups showed significant differences in ∆E before and after aging (p>.05); ∆E remained in the range of clinical acceptance ∆E.05). Also, one-way analysis of variance showed no significant difference in ∆E among the studied groups (p=0.71). Before aging, the difference in contrast ratio (CR) of the specimens was significant (p=0.00). The Tukey post-hoc test revealed significant differences between Variolink Veneer and dual-polymerized Variolink (p=0.02), Variolink Veneer and Multilink (p
