Influence of modeling liquids on the color adaptation and optical properties of single and simply shade resin composites

Objectives This study evaluated the effect of different interlayer modeling liquids on the color adaptation and translucency of single- and simply-shade resin composites using spectrophotometric analysis. Materials and methods Four resin composites were evaluated: Herculite Classic Dentin (A2), Omnichroma, Essentia Universal, and Optishade Medium. A 2-mm base layer of Herculite Classic Dentin was used in all specimens, followed by two 1-mm layers of either the same or one of the other composites. GC Modeling Liquid and Bisco Modeling Resin were applied between increments, while no-liquid specimens served as controls. A total of 144 multilayered disc specimens were fabricated and polished under standardized conditions. Color measurements (L*, a*, b*, C*) were obtained with a spectrophotometer on gray, black, and white backgrounds. Color difference (Delta E-0(0)) and translucency parameter (TP) were calculated. Statistical analyses were performed using ANOVA with a significance level of p < 0.05. Results Both composite type and modeling liquid significantly influenced optical outcomes (p < 0.001). In Omnichroma, Delta E-0(0) values were higher with Bisco Modeling Resin compared with GC Modeling Liquid, indicating greater color change. Translucency analysis showed that Bisco Modeling Resin reduced TP values in Essentia Universal, Optishade Medium, and Herculite but increased TP in Omnichroma. GC Modeling Liquid caused decreased TP only in Essentia Universal. Across all conditions, Omnichroma displayed the highest translucency, while Herculite and Optishade Medium demonstrated lower values. Conclusion The optical properties of resin composites may be influenced by the composition of modeling liquids, with pigment-free single-shade materials showing greater susceptibility to such effects.