The colors of different PFM restorations was measured according to the CIE1976- L*a*b* color scale by a Minolta chromatics meter CR-321. The color difference (AE) was calculated and then analyzed.

• 遮色瓷厚度与其遮色能力呈非线形正比关系，即厚度增加，遮色能力增加，但厚度达一定值后，色差值不再增加。