Comparison of various resin composite shades and layering technique with a shade guide

Purpose: The purpose of this study was to compare the final shade of different shades of composites (enamel shades) over a white backing (WB) and black backing (BB), and a layering technique (enamel over dentin composite) with the corresponding Vita Classical Shade tabs (VST). Materials and Methods: Composite disk specimens enamel (N = 5) shades B1, B2, A1, and A2, and dentin (N = 1) shades A1, A2, and A3 were made. The color of the VST B1, B2, A1, and A2, enamel shade disks, and layering composites of the same brand and different brands were assessed using a colorimeter over a WB and BB. The total color difference (ΔE*_ab = [(ΔL*)² + (Δa*_ab)² + (Δb*_ab) ²]^1/2) between the VST and the corresponding resin composite was calculated. The results were analyzed by one-way analysis of variance/Tukey's test (p < 0.05). Results: Overall, the L*, a*, and b* values of the enamel composite shades were significantly different from the corresponding VST. Only a few layered composites matched the L*, a*, and b* of the keyed VST. Out of the 72 combinations, 20 (28%) resulted in ΔE*_ab below the 3.3 clinically perceptible limit. CLINICAL SIGNIFICANCE Composite shades do not match well to the Vita shade guide tabs, even when the layering technique is used. As demonstrated in this study, only a few composites matched the corresponding Vita shade guide tabs.