Abstract
The purpose of the study was to investigate the influence of different tooth-colored substrates and restoration thicknesses on the final color of gingiva-colored resin-based composites (GCRBCs). Five different shades of GCRBCs [light pink (LP), dark pink (DP), orange (Or), brown (Br), and purple (P)] were used to prepare disc-shaped specimens with 2 different thicknesses: 1.0 mm, and 2.0 mm. GCRBC discs (n = 5) were placed over 3 different tooth-colored substrates (ND1, ND5, and ND9) and color parameters were assessed using a spectroradiometer. Color differences (∆E*(ab) and ∆E(00)) were calculated using CIELab and CIEDE2000 formulas and compared to 50:50% perceptibility (PT: ∆E*(ab) = 1.7, ΔE(00) = 1.1) and acceptability (AT: ∆E*(ab) = 3.7, ΔE(00) = 2.8) visual thresholds. Color variation data were statistically analyzed using two-way ANOVAs followed by Bonferroni's post hoc tests (a = 05). The ∆E*(ab) and ΔE(00) values of GCRBCs placed over ND9 substrates were significantly higher in the LP-1.0 mm and Or-1.0 mm groups that presented values above AT (p< .001).Regardless of the substrate color and GCRBC thickness applied, ∆E*(ab) and ΔE(00) values below AT were recorded in the gingival color groups of P. Substrate color significantly affected the color differences in the gingival color groups of LP, DP, and Or with a restoration thickness of 1.0 mm (p < .05). Gingival color, restoration thickness, and substrate color influenced the color differences of GCRBCs. When the gingival color was a lighter gingival color, rather than dark purple, the masking ability was decreased, especially with a restoration thickness of 1.0 mm.