Masking Ability of CAD-CAM Materials at Different Thicknesses: A Study on Color, Translucency, and Infinite Optical Thickness

Abstract

Objective: To evaluate the masking ability of different thicknesses of CAD-CAM resin-matrix and feldspar porcelain materials. Materials and Methods: Specimens (Ø7.5mm, thickness 0.5, 1.0, and 1.5mm, n=3/material) were fabricated from Lava Ultimate-LU, Grandio Blocs-GB, VITA Enamic-VE, and VITA Mark II-VM. Backgrounds were obtained from nine composite die shades (ND1-ND9, IPS Natural Die Material). Spectral reflectance was measured for samples against a black background and each ND background. CIEDE2000 color differences (ΔE00), relative translucency parameter differences (ΔRTP00), and infinite optical thickness (X∞) were calculated. ΔE00 data among materials were analyzed using Kruskal–Wallis and Mann–Whitney tests (α=0.05). ΔE00 between thicknesses and ΔRTP00 data were compared to perceptible and acceptable thresholds. Root mean square error (RMSE) and goodness-of-fit (GFC) were used as performance behavior of X∞. Results: VM exhibited the lowest ΔE00 (p<0.001) and ΔRTP00 values across all tested conditions. Overall, LU and GB did not differ for 0.5 and 1.0mm. Regardless of the background, when comparing 1.0–1.5mm, acceptable ΔE00 were observed, with only VM showing imperceptible values. Good spectral match and good comparative values of X∞ were found for LU-GB. Conclusion: The masking effect depended on material and thickness, with VM and thicker samples demonstrating superior results. In general, the spectral behavior and values of infinite optical thickness differed among materials. Clinical Significance: The masking ability of high-translucency CAD-CAM materials was influenced by composition, thickness, and the underlying tooth-colored background. Materials with lower translucency and greater thickness are recommended for highly discolored teeth. Vita Mark II was the most suitable material for restorations on darkened substrates.