Fluoride gel supplemented with sodium hexametaphosphate reduces enamel erosive wear in situ

Abstract

Objective: This study evaluated the effect of fluoride gels, supplemented or not with sodium hexametaphosphate (HMP), on enamel erosive wear in situ. Methods: Twelve healthy volunteers wore palatal appliances containing four bovine enamel discs. Subjects were randomly allocated into four experimental phases (double-blind, crossover protocol) according to the gels: Placebo (no fluoride or HMP), 1% NaF, 2% NaF, and 1% NaF + 9% HMP. Enamel discs were selected after polishing and surface hardness analysis, and treated only once with the respective gels prior to each experimental phase. Erosion (ERO) was performed by extra-oral immersion of the appliance in 0.05 M citric acid, pH 3.2 (four times/day, five minutes each, 5 days). Additional abrasion (ERO + ABR) was produced on only two discs by toothbrushing with fluoridated dentifrice after ERO (four times/day, 30 s, 5 days). The specimens were submitted to profilometry and hardness analysis. The results were analyzed by two-way ANOVA and the Student-Newman-Keuls test (p < 0.05). Results: The 1% NaF + 9% HMP gel promoted significantly lower enamel wear for ERO compared to the other groups, being statistically lower than 1% NaF and Placebo for ERO + ABR. Similarly, the lowest values of integrated lesion area were found for 1% NaF + 9% HMP and 2% NaF, respectively, for ERO and ERO + ABR. Conclusion: The addition of HMP to the 1% NaF gel promoted greater protective effect against ERO and ERO + ABR compared to the 1% NaF gel, achieving similar protective levels to those seen for the 2% NaF gel. Clinical significance: Gel containing 1% NaF + 9% HMP showed a high anti-erosive potential, being a safer alternative when compared to a conventional 2% NaF gel. (C) 2015 Elsevier Ltd. All rights reserved.