Methods: Twelve subjects took part in this crossover and double-blind study performed in 3 phases of 5 days each. Each two human enamel and dentin samples were pre-treated with experimental-NaF varnish or NaF solution (both 2.45%F, pH 4.5) in phase A; experimental-TiF4 varnish or TiF4 solution (both 2.45%F, pH 1.2) in phase B; placebo varnish or control (untreated) in phase C. The varnishes were applied in a thin layer and removed after 6 h. The solution was applied to the enamel and dentin surfaces for 1 min. The samples were used in palatal appliances and one enamel and dentin sample, treated with one of the agents, was subjected to extraoral erosion (4 times/day, Coca-Cola, 90s, ERO) or erosion plus abrasion (2 times/day, fluoride-free toothpaste and electrical toothbrush, 10s/sample, ERO+ABR). The dental tissue loss was quantified by contact profilometry (µm). The data were analysed by two-way repeated-measures ANOVA and Bonferroni post hoc test (p<0.05).
Results: All F varnishes and solutions reduced the enamel and dentine wear significantly when compared to control and placebo varnish (p<0.001). In general, there were no significant differences among the F formulations and the conditions ERO and ERO+ABR.
Conclusions: TiF4 varnish has the same protective potential as TiF4 the solution and NaF-based products to reduce human enamel and dentin erosion alone or associated with abrasion in situ.