Accelerated artificial aging and color stability in resin-based cements.

The aim of this study was to determine color change after accelerated artificial ageing (AAA) of different composite cements that are used with veneers. Five cylindrical test specimens, 15 mm in diameter and 2 mm thick, were made from a single layer of each of the following: RelyX Veneer 3M ESPE (RX), Paracore White Coltene (PC), Solocem White Opaque Coltene (SO), Resin Duo Cement Densell (DC), Panavia V5 Paste Kuraray Noritake (PA) and Panavia F2.0 Kuraray Noritake (PF) (30 specimens altogether). The specimens were light cured following manufacturers' instructions using a Coltolux LED (Coltene) unit. Initial color was determined using an Easyshade - Vita Zahnfabrik Spectrophotometer. Then, the specimens were subjected to AAA for two weeks (336 hours) with cycles of 4 hours of UV light at 60 °C and 4 hours of vapor condensation at 50 °C, successively, after which color was recorded again. Color change was determined for each specimen according to the differenceinshadeon the Vita scale before and after AAA. Results were analyzed using Kruskal Wallis test. Mean and standard deviation for each group were: RX 8.40 (1.52); PC 8.60 (3.13); SO 6.40 (3.51); DC 10.00 (0.00); PA 7.60 (3.29); PF 2.00 (0.00). The Kruskal Wallis test showed significant difference for material (p<0.05), and comparison of means showed difference between Panavia F2.0 and the other materials. A table providing equivalence between the Vita Classic and CIELAB scales was used to transfer the recorded colors to the CIELAB scale, and the color difference ΔE was calculated for each group, where ΔL, Δa and Δb are the differences in the L, a and b values before and after the AAA. The mean and standard deviation were analyzed statistically by the ANOVA test and Tukey's test. Mean and standard deviation for each group were: RX 14.94 (2.02); PC 14.51 (4.02); SO 12.08 (4.53); DC 16.31 (0.00); PA 10.9 (3.38); PF 7.24 (0.00). The ANOVA test showed significantdifferenceformaterial (p<0.05). Tukey's test showed two groups (PF-DC, RX, PA). Under the experimental conditions of this study, it can be concluded that accelerated ageing significantly affects the color stability of the resin based cements tested.