Abstract: Objective: To investigate the effects of different enamel/dentin composite shade matching methods on the resultant color of double-layered resin composite restorations. Methods: Two commercial resin composites (Z350 & NG) were included in this study. Resin specimens of each brand were prepared following 3 double-layered color matching methods:(1) dentin shade and enamel shade with the same shade but different translucencies; (2) dentin shade was darker than enamel shade; (3) enamel shade with A3 shade. The color coordinates of all the specimens and the corresponding Vita Classical Shade tabs were measured by a spectrophotometer. Color differences (ΔE) between the specimens and the corresponding Vita Classical Shade tabs were calculated. Results: There were significant differences between two commercial resin composites (P<0.05). ΔE values of Z350 were significantly lower than those of NG. Regarding to A1 shade, method 1 had the lowest ΔE value. With respect to A2 shade, the ΔE values of method 1 and 2 were lower than method 3. Conclusion: Z350 performs better results in matching the shade guide in contrast to NG. Method 1 is the best enamel/dentin composite shade matching methods for A1 shade. For A2 shade, method 1 and method 2 are better than method 3.

Key words: Composite resin, Double-layered technique, Shade matching method, Spectrophotometer, Color difference