Metameric effect between resin composite and dentin

Objectives The purpose of this study was to determine the metameric color differences between resin composites and dentin. Methods Spectral reflectance and color of five shades of one brand of resin composite were measured according to the CIELAB color scale relative to the standard illuminant D65, A and F2. Average values of human dentin were used as the optical properties of dentin. Color differences image between resin composite and dentin relative to three illuminants were calculated, and ratio of image values by the illuminant (A/D65 and F2/D65) was calculated. Ratios of changes in hue angle of resin composites by illuminant over those of dentin were compared. Results In curves of spectral reflectance, three of five shades made more than three crossing points with dentin indicating a metameric effect. Color differences between resin composite and dentin was changed when illuminant were changed from daylight (D65) to incandescent light (A) or fluorescent light (F2). Ratios of image value between resin composite and dentin by the illuminant were 0.74–0.98. Color difference relative to D65 was larger than those for illuminants A and F2. Differences in hue angle (value relative to illuminant A-that to D65) of resin composites were in the range from −10.1 to −7.2 (−13.8 to −14.0 in dentin), and those between F and D65 were 2.6–5.2 (−3.9 to −2.8 in dentin). Significance Changes in optical properties of resin composites relative to the different illuminants were different from those of dentin; therefore this inconsistency should be considered in shade matching of resin composites.