In vitro Evaluation of Surface Free Energy of Dentin after Treatment with Sodium Trimetaphosphate Associated or Not with Fluoride, Exposed or Not to Calcium

Abstract

It has been stated that sodium trimetaphosphate (TMP) promotes a more anionic dentin surface inducing greater calcium (Ca) and phosphate precipitation. The aim of the present study was to evaluate in vitro the surface free energy (γ_s) of dentin after treatment with TMP associated or not with fluoride (F), exposed or not to Ca, as well as the adsorption of TMP, F, and Ca by dentin. Bovine dentin blocks (n = 12 blocks/group) were treated with solutions containing TMP at 0, 1, 3, or 9 (w/v) followed or not by the application of Ca. These solutions were or were not associated to 1,100 ppm F. F, Ca, and TMP were determined in the solutions before and after the treatment to calculate the adsorption by dentin. To analyze the γ_s of dentin, the apolar (γ_s^LW), and polar (γ_s^AB), components were determined by contact angle measurement. Data were submitted to 2-way ANOVA followed by the Student-Newman-Keuls test (p < 0.05). TMP reduces γ_s of dentin and increases electron donor sites (γ_s⁻). Higher values of γ_s⁻ led to higher adsorption of Ca (p < 0.001). The F/TMP association did not change γ_s or γ_s^LW and reduced the values of γ_s⁻, but the adsorption of Ca was higher. There was correlation between the adsorption of TMP and γ_s⁻ (Pearson’s r = 0.801; p < 0.001) and F (Pearson’s r = 0.871, p < 0.001). It is possible to conclude that TMP increased γ_s⁻ and Ca adsorption, and reduced γ_s. The association with F increased the adsorption of TMP without rising γ_s⁻; however, there was higher adsorption of Ca.