Efficacy of toothpaste containing activated charcoal on the color change and effect on enamel surface roughness and wear

Abstract

The whitening toothpastes are generally based on abrasives and/or chemical agents. The oral care industry has been developing a range of products used for extrinsic stains removal. Toothpastes containing activated charcoal are getting more popular, and its supposed mechanism of action is based on hindering pigment adsorption on the tooth surface. Despite their growing use, a lack of clarity regarding efficacy and safety is associated to such products, and studies with methodologies aimed at simulating clinical conditions with greater reliability are required. Thus, in this study, we will evaluate the effect of toothpastes containing activated charcoal on tooth color change and enamel surface roughness, considering their chemical (without abrasion) and chemical-mechanical (with abrasion) mode of action. In addition, surface enamel loss after prolonged brushing will be evaluated. Polished bovine enamel/dentin specimens will be divided into six treatments: deionized water (negative control - NC); Colgate® Maximum Anti-cavity Protection (Traditional toothpaste - positive control - PC); Colgate® Luminous White Activated Charcoal (LW); Oral-B® 3D White Therapy Charcoal (3DW); Curaprox® Black is White (BW); Dermavita® Whitemax (Activated Charcoal Powder - WP). In phase 1, the mechanisms of action involving or not abrasion (chemical and chemical-mechanical) will be tested. A staining/treatment cycle will be performed (immersion in staining solutions - 10 min, artificial saliva - 30 min and in toothpastes slurries - 2 min) 28 times, simulating four weeks of treatment. In chemical/mechanical challenge groups, abrasion will be performed in a brushing machine (15s - 200g) during the exposure to slurries. Color (L*a*b*) and surface roughness (Ra) will be measured by a reflectance spectrophotometer and a stylus profilometer, respectively. In phase 2, the abrasive potential of toothpastes will be evaluated by measuring the surface loss with profilometry. Additional specimens will be divided into the same groups tested in the phase 1 experiment. They will then be subjected to 100,000 abrasion cycles. Profilometric analyses will be performed at five periods: initial, after 25,000, 50,000, 75,000 and 100,000 cycles to determine the enamel surface loss (¼m). The data will be subjected to appropriate statistical analysis, according to the application of normality and homoscedasticity tests, at a significance level of 5%. (AU)