Effect of fluoride varnish supplemented with sodium trimetaphosphate on enamel erosion and abrasion
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Purpose: To assess in vitro the effect on enamel erosion (ERO) and erosion followed by abrasion (ERO+ABR) of varnishes with different fluoride concentrations, supplemented or not with sodium trimetaphosphate (IMP). Methods: Bovine enamel blocks were randomly divided into six groups according to the type of varnish used: placebo (no F), NaF 5%, NaF 2.5%, NaF 2.5% plus TMP 3.5%, NaF 2.5% plus TMP 5%, NaF 2.5% plus TMP 10%. Varnishes were tested for ERO and ERO+ABR, separately for 3 and 5 days. ERO was done by immersion in Sprite Zero (5 minutes, 4x/day), while ERO+ABR was performed by brushing for 15 seconds after each erosive challenge. Enamel wear (mu m) and cross-sectional hardness (Delta KHN) were assessed after the experimental periods. Data were analyzed by ANOVA, Tukey's test and Pearson's correlation coefficient (P< 0.05). Results: Varnishes supplemented with TMP promoted significantly lower wear and hardness loss when compared to the other treatments in all conditions studied (139 0.05). Similar wear rates were observed for the placebo, NaF 2.5% and NaF 5% varnishes (P> 0.05). Greater wear was observed after 5 days of ERO and ERO+ABR when compared with 3 days (P< 0.05). Positive and significant correlations were found between enamel wear and Delta KHN. No dose-response relationship was found between TMP concentration and wear and hardness. It was concluded that fluoride varnishes supplemented with TMP had a higher protective effect against ERO and ERO+ABR, which was associated with a reduction in enamel softening.