Assessing Color Inconstancy of CAD/CAM Materials: Influence of CIE White LED Illuminants and Substrate Shade

To assess how the CIE white LED illuminants and substrate shade impact the color inconstancy of high-translucency CAD/CAM materials.

From the spectral reflectance factors of Lava Ultimate-LU, Grandio blocks-GB, VITA Enamic-VE, and VITA Mark II-M specimens (n = 3/material) measured on nine background shades (ND1-ND9), the corresponding colors under D65, A, and nine CIE white LED illuminants were computed using the CIECAT16. Color differences (ΔE₀₀) between specimens illuminated by the D65 and other illuminants were determined. The total color differences were evaluated in terms of the corresponding variation in lightness, chroma, and hue to calculate %ΔL₀₀, %ΔC₀₀, and %ΔH₀₀. ΔE₀₀ data were compared to perceptible and acceptable thresholds.

Overall, all materials exhibited acceptable color mismatch for LEDs B3, B4, and B5 and all ND shades, with exceptions for ND6. RGB produced the highest ΔE₀₀ values, indicating an unacceptable match (ΔE₀₀ > 5.4). Less saturated ND1 and ND9 resulted in the smallest ΔE₀₀ values. %ΔL₀₀, %ΔC₀₀, and %ΔH₀₀ values revealed that color differences were primarily due to changes in chroma and/or hue across all different materials, illuminants, and substrate shades.

The color inconstancy of CAD/CAM materials was affected by the CIE white LED illuminants and by substrate shade. The findings highlight the importance of considering substrate shade and illuminant type on the color appearance of restorative materials, with implications for material selection in esthetically demanding clinical scenarios. This is especially relevant for translucent restorations planned over dark and saturated abutment teeth.