Impacto do verniz fluoretado sobre o efeito protetor de um dentifrício contendo estanho e fluoreto contra o desgaste erosivo-abrasivo do esmalte: estudo in vitro

Background: Erosive tooth wear results from repeated exposure to dietary or intrinsic acids and mechanical forces. Purpose: To determine whether fluoride varnish pretreatment enhances the protection provided by a tin- and fluoride-containing toothpaste against erosive-abrasive enamel wear. Methods: In this in vitro study, 52 human enamel specimens from 30 third molars were allocated to four groups (n = 13): fluoride varnish pretreatment followed by tin- and fluoride-containing toothpaste (FV), the same toothpaste without pretreatment (PC), fluoride varnish pretreatment followed by fluoride-free toothpaste (FV-C), and fluoride-free toothpaste without pretreatment (NC). Specimens underwent 10 days of erosive-abrasive cycling. Enamel loss was measured by contact profilometry and analyzed with two-way analysis of variance and model-based simple-effect contrasts. Results: Mean enamel loss (± standard deviation) was 7.34 ± 3.98 μm (FV), 18.80 ± 4.72 μm (PC), 8.64 ± 4.74 μm (FV-C), and 22.58 ± 4.26 μm (NC). Varnish pretreatment (p < 0.001) and toothpaste formulation (p = 0.044) had significant main effects. Their interaction was not statistically significant (p = 0.317). PC had lower enamel loss than NC (p = 0.034). FV and FV-C did not differ significantly (p = 0.459). Conclusion: Fluoride varnish pretreatment reduced enamel loss under these experimental conditions. The tin- and fluoride-containing toothpaste reduced enamel loss relative to the fluoride-free toothpaste without varnish pretreatment. After pretreatment, the difference between toothpaste formulations was not statistically significant. These findings do not establish treatment equivalence or exclude additional benefits under clinical conditions.