Effect of whitening toothpastes and activated charcoal powder on enamel wear and surface roughness

This study aimed to evaluate surface roughness (Sa), roughness profile (Rv), and enamel wear after brushing with different whitening toothpastes and charcoal powders. Sixty (n = 10) bovine enamel blocks (6 x 6 x 3 mm) were randomly distributed into six groups according to toothpaste type: regular toothpaste (CONT), toothpaste containing 2% hydrogen peroxide (HP), toothpaste containing titanium dioxide (TiO2), toothpaste containing charcoal (COAL), toothpaste containing charcoal and TiO2 (COAL+TiO2), and activated charcoal powder (COAL_PWD). Each block was subjected to 30,000 reciprocal cycles at a 1:3 proportion slurry. After brushing, the blocks were analyzed using an optical profilometer to determine Sa, Rv, and enamel wear. In addition, representative 3D images of each group and wear profiles were obtained. Sa was analyzed using generalized linear models followed by Bonferroni correction, whereas Rv was analyzed using one-way analysis of variance. After brushing, COAL and COAL+TiO2 showed higher Sa values than COAL_PWD. However, no significant difference was observed in Sa between whitening toothpaste and COAL_PWD, and CONT (p > 0.05). In addition, no differences were observed among the groups in Rv (p > 0.05). Conversely, enamel wear was higher for TiO2, COAL, COAL+TiO2, and COAL_PWD than for CONT. CONT showed the least enamel wear, whereas HP showed intermediate values. Representative 3D images and line profiles showed lower step-height and lower mean surface losses for the CONT and HP groups than for the other groups. Whitening toothpastes and COAL_PWD did not increase Sa or Rv compared with CONT, while CONT demonstrated lower enamel wear.