Objective: To investigate the color difference using both ΔE*ab and CIEDE2000 formulas of all combinations of all enamel and dentin shades of three different composite systems with three different shade guides, to compare the coverage error (CE) of the shade guides for each composite and to investigate whether coverage error is affected by enamel shade layer thickness (0.5 vs 1 mm).
Materials and methods: Disk specimens from all enamel and dentin shades of Essentia, Enamel Plus HRi, and IPS Empress Direct composites were fabricated. Color measurements were performed for all enamel-dentin combinations and for two thicknesses per enamel shade: 0.5 and 1 mm. Color was measured for three shade guides: Vitapan Classical, 3DMaster, and Ivoclar. Minimum color difference between layered composites and shade tabs, closest shade tab match and CE of all shade guides were calculated for all composite shade combinations.
Results: In most cases, the closest match was a mismatch. CE of 3DMaster was significantly lower for IPS Empress Direct and Enamel Plus HRi at 0.5 mm enamel thickness. Shade guides exhibited higher lightness values compared to composites and composites lower chroma values compared to shade guides.
Conclusions: Shade guides do not match well to the layered composites. 3DMaster performed better than the other two shade guides, in most cases.
Keywords: color difference; composite; coverage error; layering; shade guides.
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