The effect of magnesium hydroxide-containing dentifrice using an extrinsic and intrinsic erosion cycling model

•A protective effect of Mg(OH)2 dentifrice on initial enamel erosion is indicated.•Mg(OH)2 dentifrice can decrease initial erosion more efficiently than NaF dentifrice.•Mg is a promising component to be evaluated in clinical studies in erosion prevention. To evaluate, in vitro, the effect of Mg(OH)2 dentifrice, and the influence of the number of experimental days, on the extrinsic (citric acid –CA) and intrinsic (hydrochloric acid –HCl) enamel erosion models. Human enamel slabs were selected according to surface hardness and randomly assigned to 3 groups (n=9) as follows: non-fluoridated (negative control), NaF (1450ppm F- positive control) and Mg(OH)2 (2%) dentifrices. The slabs were daily submitted to a 2-h period of pellicle formation and, over a period of 5days, submitted to cycles (3×/day) of erosive challenge (CA 0.05M, pH=3.75 or HCl 0.01M, pH=2 for 30s), treatment (1min −1:3w/w of dentifrice/distilled water) and remineralization (artificial saliva/120min). Enamel changes were determined by surface hardness loss (SHL) for each day and mechanical profilometry analysis. Data were analyzed by two-way ANOVA followed by Tukey’s test to % SHL and one-way ANOVA to profilometry (p