Do adhesive systems influence the color match of resin composites?

This in vitro study evaluated the influence of adhesive systems on the color match of a resin composite with different translucencies.

Sixty disk-shaped specimens were made with A2 and opaque A2 (OA2) shades of nanohybrid resin composite Z250 XT. Specimens of each shade (n = 30) were randomly reassigned to 3 subgroups according to adhesive system: a 2-step etch-and-rinse adhesive (Adper Single Bond Plus), a 2-step self-etch system (Clearfil SE Bond) and a universal adhesive (Scotchbond Universal Adhesive). The bonding agents were applied to resin composite specimens following the manufacturers’ recommendations. Additionally, 5 disk samples of each adhesive system were prepared. Colorimetric evaluation (CIE L*a*b* system) was performed immediately after polishing the sample and application of the adhesive systems. Color changes (ΔE and ΔE₀₀) were calculated between 2 measurements. Color coordinates L*, a* and b* of the adhesive disks were also assessed. The data obtained were analyzed using ANOVA and Tukey’s post hoc test (α = 0.05).

The application of Scotchbond Universal Adhesive to the resin composite A2 shade resulted in the highest color change (p<0.01; ΔE = 3.1 ± 0.7 and ΔE₀₀ = 1.8 ± 0.4). However, no significant difference was observed among adhesive systems when applied to the resin composite OA2 shade (p>0.05). Scotchbond Universal Adhesive revealed augmented yellowing and greening in comparison with other experimental groups.

The universal adhesive tested resulted in higher visually perceptible color changes when using a more translucent resin composite shade, but this was clinically acceptable.