Effect of a 4% titanium tetrafluoride (TiF4) varnish on demineralisation and remineralisation of bovine enamel in vitro

Objectives This in vitro study assessed the effect of a 4% TiF4 varnish on demineralisation and remineralisation of sound enamel and artificial carious enamel lesions, respectively. Methods Bovine sound and carious enamel (n = 110) were randomly allocated to each type of varnish: Duraphat®-D (NaF, 2.26%F, pH 4.5, Colgate-Brazil, n = 30), Duofluorid®-F (NaF, 2.71%F, pH 8.0, FGM-Brazil, n = 30), TiF4–T (2.45%F, pH 1.0, FGM-Brazil, n = 30) and no-fluoride–P (FGM-Brazil, pH 5.0, n = 20). For the formation of artificial enamel caries, half of the blocks were immersed in 32 mL buffer acetate solution (16 h), whereas the other half was maintained sound. The varnishes were applied onto the enamel surfaces. Thus, the samples were subjected to pH cycles (37 °C) for 7 days. The response variables tested were surface and cross-sectional hardness. Data were tested using Kruskal-Wallis test (p < 0.05). Results All F varnishes significantly reduced demineralisation and increased remineralisation in comparison to placebo. The TiF4 did not significantly reduce the surface enamel softening when compared with the other F varnishes, but it decreased the loss of subsurface hardness to the same extent. In enamel blocks with previous artificial carious lesions, the TiF4 significantly improved the rehardening compared to the other varnishes up to 30 μm depth. Conclusions The TiF4 varnish was able to decrease the demineralisation and increase the remineralisation of previously sound and carious enamel, respectively. It was equally effective compared to NaF varnishes on reducing the demineralisation at subsurface, but it was more effective on improving the remineralisation at surface and subsurface.