Color difference of all-ceramic materials by the change of illuminants

To determine the differences in color and color parameters (lightness, chroma and hue) of simulated layered all-ceramic specimens at a clinically relevant thickness under three CIE standard illuminants.

Seven all-ceramic core materials of A2-corresponding shade, one sintering ceramic and one alloy core as references were prepared in clinically relevant thicknesses (0.4 to 0.8 mm). A2- and A3-corresponding shades of each of the recommended veneer ceramics were fabricated so that the thickness of the layered specimens was 1.5 mm. Bovine dentin was also used as a reference. Color was measured relative to the CIE standard illuminants D65, A and F2 with a reflection spectrophotometer. Differences in color and color parameters by the change of illuminants were calculated. Repeated measures two-way ANOVA with the fixed factor of the brand of ceramics on the difference in color and color parameters by the change of illuminants (D65 to A, D65 to F2 and A to F2) was performed (alpha = 0.05).

Color difference (deltaE*ab) was in the range of 0.6 to 0.8 for bovine dentin, 1.3 to 3.4 for A2-veneer layered specimens and 1.6 to 4.2 for A3-veneer layered specimens. Differences in color and parameters were significantly influenced by the brand of the ceramics and the combination of illuminants (P < 0.05).