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 (deltaE(ab)*) between resin composite and dentin relative to three illuminants were calculated, and ratio of deltaE(ab)* 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 deltaE(ab)* 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.