[Color change by thickness and background color on visible light-cured composite resins]

The effects of thickness and background color on the color of five commercial light-cured composite resins were studied by a dental color meter using the CIE 1976 L*a*b* color system. As thickness increased from 1.0 to 4.0 mm, values of L*a*b* decreased for white and dentin color background but showed no obvious difference in color for a black background. the color of composite resins were not in fluenced by background color in a thickness of 4.0 mm. The values of color difference for 1.0 and 2.0 mm thick samples have a larger value than the same 4.0 mm samples. The color difference was recognized even for the same shade name in five representative kinds of composite resins.