Abstract:Objective:To study the color differences of metal ceramic restorations and Vitapan classical shade guides in daylight-color,cool white and warm light sources. Methods:On the neutral gray background,CIE1976 L*a*b* color system,a digital camera and computer were selected to measure and compare the characteristics of A2 shade slice in the shade guides and two groups of metal ceramic restorations in three different light sources. Results:To the same group of metal ceramic restorations,the color differences were more obvious than 1.5NBS in three different light sources. The color difference between metal ceramic restorations and A2 shade slice was the most insignificant in the daylight-color light source. Conclusion:Color differences could be found between the shade guides and metal ceramic restorations in three different light sources. Daylight-color light source is better than the other two for the colorimetric.