Surface properties and susceptibility to staining of a resin composite after brushing with different whitening toothpastes.

Objectives: This study investigated the effects of different whitening toothpaste (WT) on the surface properties and staining susceptibility of a resin composite. Methods: Cylindrical samples were prepared with a micro-hybrid resin composite and were randomized into groups according to the toothpaste (n = 12): distilled water (DW), regular toothpaste (RT), WT with silica + pyrophosphate (WT-S/P), WT with pentaphosphate and pyrophosphate (WT-P/P), WT with hydrogen peroxide and pyrophosphate (WT-HP/P) and WT with charcoal and pyrophosphate (WT-Ch/P). The samples were brushed for 825 cycles in an automatic brushing machine, simulating 30 days of brushing. After that, an immersion in coffee (10 mL/sample) was performed for 30 minutes for 30 days. The analyses of color, surface microhardness (SMH), and surface roughness (Ra) were performed at the initial time, after brushing with toothpaste and after immersion in coffee. The ΔL*, Δa*, Δb*, ΔEab, Δand E00 values were calculated comparing after toothpaste with initial time and after coffee with after toothpaste. Data were analyzed using a mixed linear model for repeated measures (SMH), Kruskal-Wallis, Dunn, Friedman, and Nemenyi tests, with α = 0.05. Results: For ΔL*, the WT-Ch/P group had the lowest values and differed from the other groups comparing the after toothpaste with the initial time interval (p < 0.001). The WT-Ch/P group had the lowest SMH values in after-toothpaste time (p < 0.001). In after-toothpaste time and after coffee time, the WT-S/P group had the highest Ra values and differed from the groups except the WT-Ch/P group (p < 0.001). Conclusions: The toothpaste composition affects the surface characteristics and susceptibility to staining of the resin composite. The charcoal-based toothpaste had the worst performance for the color analyses and SMH.