Influence of Use of Opaque Single-Shade Composite Resin and Residual Dentin Thickness on the Esthetic Performance of Single-Shade Composite Resin

This study aimed to analyze the effect of combining a single-shade composite resin with an opaque single-shade composite resin on the color adjustment potential (CAP) and color difference (ΔE*ab) of restorations at various residual dentin thicknesses. One single-shade composite resin (Omnichroma [OM]), one opaque single-shade composite resin (Omnichroma Blocker [OB]), and two multi-shade composite resins (Filtek Z350 XT [FT] A2D shade and Estelite Sigma Quick [ES] OA2 shade) were included in this study. Using first molar denture teeth in A2 shade, both single and dual specimens were fabricated at residual dentin thicknesses of 0, 1, and 2 mm. The translucency parameter (TP), ΔE*ab , and CAP were calculated for the control group and 3 experimental groups. The FT group exhibited the highest ΔE*ab values and the lowest CAP (p < 0.0083), while the highest TP values were observed in the control group (p < 0.0083). CAP and ΔE*ab did not show significant differences based on residual dentin thicknesses in most groups. TP was significantly higher at 0 mm residual dentin thickness than at 1 mm and 2 mm in all groups (p < 0.0167). When the perceptibility threshold was set at ΔE*ab ≤ 2.0, the ES and OB groups exhibited color differences within the threshold. These findings suggest that combining a singleshade composite resin with an opaque single-shade composite resin can contribute to the esthetic performance of restorations.