Can TiF₄ varnish or TiF₄/NaF solution stain eroded and sound enamel?

This study evaluated the staining potential of TiF₄ varnish and TiF₄/NaF solution on both sound and previously eroded enamel in vitro.

One hundred and eighty bovine enamel samples were polished; half of them remained sound and the other half was eroded (4 × 90 s each, using a 0.1% citric acid). Thereafter, the baseline color reading was performed (T₀). The samples were then subdivided into the following treatments: TiF₄ varnish (24,500 ppm F, 1 × 6 h), NaF varnish (24,500 ppm F, 1 × 6 h), placebo varnish (1 × 6 h), TiF₄/NaF solution (500 ppm F, 6 × 1 min), Erosion Protection-Elmex^® (500 ppm F, 6 × 1 min) and control (water, 6 × 1 min). Between the applications, the samples were exposed to artificial saliva for 30 min. The color changes were measured immediately after the applications (T₁-T₆) and after the exposure to artificial saliva (S₁-S₆) by using a spectrophotometer (Vita EasyShade^®). The ΔE₀₀, L*, a* and b* data were compared using 2-way ANOVA/Tukey (p < 0.05).

TiF₄ varnish induced significantly higher color change (ΔE₀₀) compared to NaF and placebo varnishes on sound enamel immediately after application, but not after saliva exposure. TiF₄/NaF solution induced lower ΔE₀₀ values compared to control on sound enamel; however, no differences were found between TiF₄/NaF and Elmex^®. For eroded, no differences were seen between the tested varnishes and solutions. Both types of fluoride solutions increased the yellow appearance of enamel, while the varnishes did not.

The color changes induced by the experimental TiF₄ products are similar to the commercial ones.

Both TiF₄ varnish and TiF₄/NaF solution have shown staining potential similar to commercially available varnish (NaF) and solution (Elmex^®) on sound and eroded enamel. These findings support the conduction of clinical trials, which, in the future, may lead to the commercialization of these products.