Masking ability of indirect restorative systems on tooth-colored resin substrates

Objective To evaluate the masking ability of different indirect restorative systems (IRS) on tooth-colored resin substrates. Methods A1-shaded specimens from 5 IRS (LDC-IPS e.max^® CAD; YZW-Zenostar Zr Translucent; PICN-Enamic; YLD-T-IPS e.max^® ZirCAD + IPS e.max Ceram; CAD-on-Zenostar Zr Translucent + Crystall./Connect + IPS e.max^® CAD) were fabricated. Specimens (n = 5) were cemented with a resin luting agent (Variolink^® N; shade White) on three different shades (ND3, ND8 and ND9) of a tooth-colored resin substrate (IPS Natural Die Material). Spectral reflectance and color coordinates were measured using a spectroradiometer under standardized lighting conditions (CIE D65 illumination) and optical geometry 0/45°. Color differences (ΔE_ab^* and ΔE₀₀) from cemented specimens and CIELAB- and CIEDE2000-based translucency parameter (TP and TP₀₀) from non-cemented specimens were calculated. Data was statistically analyzed using one-way ANOVA and Tukey's tests (α = 0.05). ΔE values were also analyzed using perceptibility (PT = 1.22 ΔE_ab^* units; 0.81 ΔE₀₀ units) and acceptability (AT = 2.66 ΔE_ab^* units; 1.77 ΔE₀₀ units) thresholds. Results The cemented specimens of CAD-on, LDC, YZW and PICN on different substrates (ND3-ND8, ND3-ND9 and ND8-ND9) showed different ΔE_ab^* and ΔE₀₀ values (p ≤ 0.05), which were above AT. YLD-T showed ΔE_ab^* and ΔE₀₀ values below AT for all comparisons. Lowest and highest TP and TP₀₀ values were obtained for YLD-T and PICN, respectively (p ≤ 0.05). Significance Resin-cemented YLD-T on different tooth-colored substrates showed less translucency as well as smaller color differences (below acceptability threshold), indicating the best masking ability among evaluated systems.