Shade distribution of indirect resin composites compared with a shade guide

Objectives To determine the distributions in color parameters of two brands of indirect resin composite (belleGlass NG: 16 shades; Sinfony: 26 shades), and to compare the color of these materials with the key shade guide (Vitapan classical shade guide). Methods Resin composites were packed into a mold and light cured with a light-curing unit, and then were post-cured in each proprietary curing chamber. Color was measured according to the CIELAB color scale on a reflection spectrophotometer. Color distributions were evaluated based on the value–chroma scale and the CIE a*–b* scale. Color differences between each shade material and the corresponding shade tab, and between each material and the nearest shade tab, which showed the smallest color difference, in the Vitapan classical shade guide were calculated. Results For both materials, the value–chroma distribution was mainly correlated with the shade groups in each material, not with the shade designations themselves. The CIE a*–b* distribution showed trends in each shade group for both materials. Compared with the Vitapan classical shade guide tabs, the range of color differences with the corresponding shade tab was 14.7–23.0 image units, all of which were perceptible (image). Conclusions In clinical shade matching, color distribution of each material should be considered and color discrepancy with the corresponding key shade guide tab should be also considered.