This in vitro study aimed to evaluate color recovery after 7 and 15 days of brushing with six whitening toothpastes that have different whitening mechanisms on coffee-stained anterior microhybrid composite resin. It also investigated the effects of brushing on surface microhardness. Disc-shaped specimens (2 mm thick, 10 mm in diameter) were prepared from a microhybrid anterior composite resin (GC G-ænial Anterior) (n = 10) and immersed in a coffee solution for 5 days to induce discoloration. Afterwards, the specimens underwent brushing simulation for 7 and 15 days using six whitening toothpastes and a non-whitening control toothpaste (Sensodyne Pronamel). Color changes were measured using a spectrophotometer based on the CIEDE2000 system, and surface microhardness was assessed with a Vickers microhardness tester. Statistical analysis was performed using repeated-measures analysis of variance (ANOVA). After coffee staining, all specimens showed discoloration exceeding the clinical acceptability threshold (ΔE00 > 1.8). After 7 days of brushing, significantly greater color recovery was observed in the Signal Whitening System, Colgate Optic White, and Sensodyne Extra Whitening groups compared to other toothpaste groups (p 1.8), with the highest color recovery noted in the Signal Whitening System group (ΔE00 = 2.52 ± 0.91). Regarding surface microhardness, significant increases were observed in all groups after brushing (p < 0.05). The Pronamel, Colgate Optic White, and Advance groups demonstrated significantly higher Vickers microhardness values compared to the Rocs group at the end of the 15-day period (p < 0.05).
Yapar et al. (2026) studied this question.