Difference in the colour and colour change of dental resin composites by the background

summary The objective of this study was to evaluate the difference in the colour and colour change of dental resin composites over commonly used two backgrounds. Colour of five uncured and cured resin composites before and after polishing with 600‐, 1000‐ or 1500‐grit SiC paper was measured according to the CIELAB colour scale relative to the illuminant D65 over a white background (WB; reflectance = 91·57%) and a light trap (LT; reflectance = 0·01%) on a reflection spectrophotometer with the SCE geometry. Colour difference (ΔE*ab) by the background, and by the specimen conditions over each of two backgrounds was calculated. ΔE*ab values between the same specimen by the background were 2·38–11·60. ΔE*ab values by the specimen condition were varied by the background, and ΔE*ab between cured/polished specimens over WB were significantly higher than those over LT (P