The safety of baking soda as an abrasive of commercial toothpastes has already been demonstrated and are based on the high solubility of baking soda and its lower or equivalent hardness in relation to enamel and dentin, respectively. However, the use of baking soda by patients that seek to remove extrinsic staining to whiten their teeth at-home brings some concerns regarding the safety of baking soda. In addition, potential deleterious effects caused by baking soda may be concentration-dependent and/or be associated to the load applied during brushing. Thus, the aim of this study was to assess the abrasion caused in enamel and root dentin by plain or diluted (slurries containing different concentratuion of baking soda), under brushing loads of higher or lower magnitude. Enamel and root dentin slabs (3x3x2 mm) will be secctioned from human third molars and then embedded, flattened and polished in a pneumatic grinder. According to sample size calculation and random arrangement, 8 samples will be alloocated into 12 groups, composed by the combination among 5 different baking soda concentrations in artificial saliva (1:0 = plain, 1:1, 1:2, 1:3 e 1:4, by weight) or a control toothpaste (Crest cavity Protection, 1:3, by weight) with 2 brushing load magnitudes (1 and 3 N). Two additional groups will be brushed in the presence of artificial saliva under 1- and 3 N load. Based on the group that the samples pertain, they witll be subjected to brushing in an equipment recommended by the ISO 11609 (2017) and which simulated clinically observed parameters. Then, the samples will be analysed for wear (surface loss) using an optical profilometer. In order to identify the effect of baking soda concentration, brushing load and the interaction between these independent variables, if normality and homocedasticity are met, both enamel and root dentin data will be treated with two-way analysis of variance, followed by multiple comparison test. Alternatively data transformation or non-parametric approaches may be applied. The significance level will be set at 5%.
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