Translucency and Masking Ability of Single-Shade Opaque Composite Resin Compared with Conventional Opaque Composite Resins According to Thickness

This study aimed to evaluate and compare the translucency and masking ability of a single-shade opaque composite resin with those of conventional opaque-shade composite resins of varying thicknesses. Three types of composite resin specimens, Omnichroma Blocker, Filtek Z350 XT A2D, and Gradia Direct Anterior AO2, were fabricated with a diameter of 8.0 mm and thicknesses of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 4.0 mm. Three background plates were tested: a white tile, a black tile, and a C4-shade porcelain plate. The CIE L*a*b* values of the resin specimens on each background and in their inherent color were measured using a spectrophotometer, and the translucency parameter (TP) and color difference (ΔE*ab) were calculated. In all groups, TP and ΔE*ab values decreased with increasing specimen thickness. The black background was masked at a thickness of 1.5 mm or more, while the C4-shade porcelain background was masked at all tested thicknesses. Within the limitations of this study, a minimum thickness of 1.5 mm is recommended to mask intraoral darkness, and a thickness of 0.5 mm or greater is recommended to mask stained or discolored tooth structures.