Effect of varnish with trimetaphosphate on erosion/abrasion of the enamel

Objectives: The aim of the present study was to evaluate in situ the effect of fluoride varnish with sodium trimetaphosphate (TMP) on the erosion (ERO) and erosion followed by abrasion (ERO+ABR). Methods: Bovine enamel blocks were selected through surface hardness and randomized into five groups: Placebo (without fluoride), 2.5%NaF, 5%NaF  and 2.5%NaF plus 5%TMP. Ten volunteers wore palatal appliances with four blocks in a double-blind crossover study. The varnish remained in contact with the enamel for 6 hours and it was completely removed, then the appliances was submitted to erosive challenge through immersion in citric acid (0.05M, pH 3.2) for 5 minutes, 4 times to the day, during 5 days. In the sequence, all the blocks received treatment with slurry from placebo dentifrices (1:3). Half of each appliances was submitted to ERO+ABR process by brushing for 15 seconds. The wear of the enamel surface (µm), surface (SHf) and cross-sectional (ΔKHN) hardness were evaluated. The data were subjected to analysis of variance followed by Student-Newman-Keuls test (p<0.05). Results: The wear observed in ERO was lower than that seen in the wear ERO + ABR in all groups. The increase of fluoride was related with a reduction of the wear and of the mineral loss in both challenges. Lower values of wear and ΔKHN were observed in 2.5%NaF plus 5%TMP group, when compared to other groups of the study in both conditions ERO and ERO+ABR (p<0.05). The 2.5%NaF plus 5%TMP group showed the highest values of surface hardness final (SHf) being statistically similar to the 5%NaF group. Conclusion: The addition of TMP in a fluoride varnish formulation enhance its ability against erosion and erosion followed by abrasion.