İkbal Esra PEHLİVAN, Sema KAYA
Eastern Journal of Medicine (EJM) - 2026;31(4):879-891
Resin composites may undergo discoloration and surface degradation after exposure to acidic pigmented beverages, while bleaching may further affect their properties. This study evaluated color difference (DeltaE ??), whiteness index (WI ?), and surface roughness (Ra) of conventional, group-shade, and single-shade composites during a şalgam-induced staining and bleaching cycle. Disk-shaped specimens (8 x 2 mm) were prepared from five resin composites (n = 10/group). Measurements were performed at baseline (T1), after 24 h (T2) and 1 month (T3) of şalgam immersion, and 1 day (T4) and 10 days (T5) after bleaching with 35% hydrogen peroxide. DeltaE ?? and WI_D were determined spectrophotometrically and Ra using a contact profilometer. WI_D changes were analyzed using Friedman tests, between-material differences using Kruskal-Wallis and Dunn-Bonferroni tests, and material-by-time interactions using rank-based permutation tests. Significant material-by-time interactions were detected for DeltaE ?? and WI_D (both p < 0.001) and Ra (p = 0.049). At T3, Essentia Universal (S1) showed the greatest discoloration (DeltaE ?? = 11.47 +/- 2.75), whereas OptiShade (G2) showed the lowest (3.39 +/- 0.25). After bleaching, Filtek Easy Match (G1) showed the greatest whitening recovery (82%), while S1 showed the lowest ( -21%). Surface roughness increased after staining, particularly in S1, and decreased after bleaching. The tested composites showed material-dependent variability in color stability, whiteness recovery, and surface roughness. Group-shade composites showed more consistent overall performance, whereas single-shade composites showed greater variability. Material selection should consider long-term esthetic behavior in addition to initial shade matching.
