Multidimensional instrumental and visual evaluation of metamerism in single-shade resin composites: effects of color-matching technology, underlying color, thickness, and translucency.

The metameric behavior of single-shade resin composites with different color-matching technologies and the effects of substrate color, material thickness, and translucency were evaluated using instrumental and visual methods. Disc-shaped specimens (1 × 6 mm and 2 × 6 mm) were prepared from three single-shade resin composites incorporating Smart Chromatic Technology (Omnichroma), Adaptive Light Matching Technology (Charisma Diamond One), and Adaptive Response Technology (SimpliShade Universal). The modified metamerism index (MImod) and translucency parameter (TP) were measured spectrophotometrically under D65, A, and F2 illuminants on standardized white and black backgrounds. Visual assessment (ΔV) was performed by two calibrated observers, and the data were statistically analyzed. MImod values differed significantly among the color-matching technologies, whereas TP values did not. MImod values were higher on white than on black backgrounds. Material thickness significantly effected TP values and MImod values on the black background but not on the white background. Visual assessment demonstrated good interobserver agreement, and a strong negative correlation was observed between MImod and ΔVmed on the black background. These findings indicate that metameric behavior is influenced by color-matching technology, substrate color, and, under black-background conditions, material thickness. Despite similar translucency values, differences in metameric behavior suggest that translucency alone does not explain metamerism, and visual perception of metamerism is also effected by substrate color.