Evaluation of Discoloration After Thermocycling in CAD/CAM Blocks of Different Thicknesses

The study aims to evaluate the color of CAD/CAM blocks of different thicknesses after thermocycling as in-vitro. A total of 180 samples (n=10) were prepared in 2 thicknesses (0.5mm, and 1.0 mm) from various CAD/CAM blocks of different structures (Katana UTML, Prettau® 4 Anterior® Dispersive, IPS e-max Cad, Vita YZ-XT, Vita YZ-T, Vita Suprinity PC, Vita Enamic, Shofu HC, G-Ceram). The color values of the samples (L*, a*, b*) were measured before and after thermocycling. The discoloration (ΔE) data obtained were statistically compared with two way-ANOVA, Tukey HSD posthoc tests, and Paired Sample T-Test (p<0.05). The highest average discoloration was found in the Katana group (ΔE=3.07) with a thickness of 1 mm, while the lowest was found in the Shofu HC group (ΔE=0.49) with a thickness of 0.5 mm. In contrast, the ΔE value was significantly different in samples with a thickness of 1 mm and 0.5 mm (p<0.05), there was no difference in the ΔE values in the groups in themselves. Discoloration values of test materials depending on thickness varied, but the difference of thickness in the same material did not affect the color change. All the color changes were clinically accepted.