RESUMO
This study investigated the isolated and combined effect of a single application of TiF4 or NaF varnish versus daily use of a solution containing a low concentration of TiF4/NaF against tooth erosion in vitro. A total of 90 bovine enamel and 108 root dentin samples were treated as follows: control (no treatment), solution containing TiF4/NaF (500 ppm F-, pH 4.4), NaF varnish (24,500 ppm F-, pH 5.0), TiF4 varnish (24,500 ppm F-, pH 1.0), TiF4 varnish + solution, and NaF varnish + solution. The erosive challenges were performed 4 × 90s/day (0.1% citric acid, pH 2.5) and, between them, the samples were immersed in artificial saliva. The tooth loss was measured using contact profilometry (after 7 days for dentin and after 7, 10, and 14 days for enamel). All treatments were effective in reducing tooth loss, except NaF varnish for enamel on day 7 (p < 0.0001). TiF4/NaF solution and TiF4 varnish did not differ with respect to enamel loss for 10 days; thereafter, TiF4 varnish lost its protective effect compared to TiF4/NaF solution. The combination of vehicles was more effective in reducing enamel loss than both varnishes on their own but not compared to the solution. For dentin, TiF4 varnish was more effective than NaF varnish, while TiF4/NaF solution and NaF varnish were similar. The combination of vehicles improved the protective effect only when compared to NaF varnish on its own (p < 0.0001). Both types of TiF4 applications, isolated or combined, were effective against tooth erosion, but some differences in their performance were seen between enamel and dentin.