The length of obturation is related to the presence of apical peridontitis and consequently to the success of endodontic treatment.

This study aimed to evaluate the surface (γ s ) and interaction (ΔG iwi ) free energy and calcium (Ca 2+ ) and phosphate (PO 4 3− ) adsorption to dental enamel treated with sodium trimetaphosphate (TMP) or calcium glycerophosphate (CaGP) that had or had not been exposed to CaPO 4 -containing solutions. Bovine enamel blocks (n = 192; 24 blocks/group) were treated (2 mL/block; 2 min) with TMP (0%, 1%, 3%, and 9%) and CaGP (0, 0.25, 0.5, and 1%) or exposed to a CaPO 4 -containing solution. The adsorption of these compounds by enamel was assessed before and after treatment. γ s and ΔG iwi and their apolar (γ s LW and ΔG iwi LW ) and polar (γ s AB and ΔG iwi AB ) components and acid-base interactions (γ s + /γ s − ) were determined by the contact angles. The data were subjected to ANOVA, followed by the Student-Newman-Keuls test (p < 0.05). The adsorption of TMP was dose dependent (p < 0.001), and it reduced γ s and γ s AB and increased ΔG iwi AB (ΔG iwi > 0) and γ s − when compared with the group without TMP (p < 0.001). The immersion in CaPO 4 -containing solu-tion increased γ s and γ s AB and reduced ΔG iwi AB (ΔG iwi > 0) and γ s − (p < 0.001). There was a correlation between the adsorption of TMP and Ca 2+ (r = 0.916; p < 0.001) and PO 4 3− (r = 0.899; p < 0.001). The adsorption of CaGP on the enamel was dose dependent (p < 0.001), reducing γ s , ΔG iwi AB (ΔG iwi < 0), γ s LW , and γ s − when compared to the group without CaGP (p < 0.001). When exposed to the CaPO 4 -containing solution, there was an increase in ΔG iwi AB (ΔG iwi > 0), γ s LW , and γ s − and a decrease in γ s AB (p < 0.001) without adsorption of Ca 2+ by enamel. It may be concluded that TMP and CaGP were adsorbed onto the enamel, producing hydrophilic and hydrophobic surfaces, respectively. TMP produces electron donor sites that induce Ca 2+ adsorption, while CaGP releases Ca 2+ into the medium.