The effect of in vitro aging on the color stability of cubic and tetragonal zirconia materials

Aim: The aim of this study is to evaluate the effect of artificial-accelerated aging (AAA) on the color stability of three types of monolithic cubic Zirconia materials of the third generation compared with tetragonal Zirconia materials of the first generation. Materials and Methods: A four groups of 10 disc-shaped specimens (10 mm × 1.2 mm) were made from the following CAD/CAM Zirconia blocks: first-generation Zirconia (Ceramill Zi LT) as a control, and three brands of third-generation Zirconia (Ceramill Zolid FX UT, Katana UTML, and Cercon XT) as the experimental groups. Ten discs from each group were subjected to the color measurement using a Spectrophotometer (Hunterlab, EasyMatch QC. Ver 4.90). Then, same discs were subjected to AAA for 3500 cycles. The data were analyzed with the one-way analysis of variance (ANOVA) and Tukey's post hoc test. Data analyses were evaluated at a statistically significance level of P < 0.05. Results: Statistically significant differences were detected in the L*, a*, and b* values among the four groups both before and after AAA. One-way ANOVA was used, which showed statistically significant differences among the groups (P < 0.001). The Ceramill ZI LT showed the greatest change in color (ΔE = 2.74 ± 0.23), followed by Katana UTML (ΔE = 1.91 ± 0.23), Ceramill Zolid FX UT (ΔE = 1.52 ± 0.43), and least change in color was seen in Cercon XT (ΔE = 1.44 ± 0.25). Tukey's post hoc test showed a statistically significantly difference among the test materials, except between Ceramill Zolid Fx UT and Cercon XT, where there was no significant difference seen in ΔE. Conclusion: The AAA protocols used in this study resulted in a significant effect in the (ΔE) of the four-tested Zirconia materials. The Ceramill ZI LT (First Generation) showed the greatest change in color and the least change in color was observed with Cercon XT (third generation). The color changes in all four tested Zirconia, though statistically significant was not a clinically perceivable