Color assimilation of resin composites with adjacent color according to the distance

Color of esthetic restorative materials shifts toward color of adjacent material.

The purposes were to determine the amount of distance-dependent color shift in resin composites toward the color of adjacent materials and to define a color shift parameter (CSP) that can quantify this phenomenon.

Three brands of resin composites, two shades for each, were investigated. Specimens of 2 (thickness) × 4 (width) × 16 (length) mm(3) were fixed in an adjustable XY stage in contact with black and white ceramic tiles at each end. Color was measured by a spectroradiometer at seven separated points in 2-mm intervals, in which P1 was 2 mm away from the black tile. Mean value of the color differences (ΔE*ab ) between P1 and each of the other measurement points (P2-P6) was defined as the CSP, in which higher CSP value indicated smaller color assimilation toward P1 color.

The range of the CSP was 7.5-12.4, which was influenced by the brand and shade of resin composites (p < 0.05).

The CSP defined in this study provided the amount of color shift of esthetic materials toward adjacent color, which indicated the color assimilation effect of these materials.

The CSP investigated in the present study might be used to compare the tendency of color assimilation of esthetic restorative materials, and proper CSP ranges for optimal color assimilation or color blocking should be further determined.