In vitro effect of calcium nanophosphate and high-concentrated fluoride agents on enamel erosion: an AFM study.

BACKGROUND: Calcium nanophosphate paste can provide ions to remineralize enamel. There are, however, no data available about the remineralizing effect of this paste on the prevention of enamel erosion, when compared with highly concentrated fluoride agents. AIM: To analyze the effect of calcium nanophosphate paste, fluoride gel, and varnish to protect against enamel erosion using surface Knoop hardness (KNH) and atomic force microscopy (AFM). DESIGN: Forty enamel blocks (4 x 4 mm) of third molars were used for 4 groups (n = 10): 1.23% fluoride gel (Fluorgel-DFL((R)) ); calcium nanophosphate paste (Desensibilize NanoP-FGM((R)) ); fluoride varnish (Duraphat-Colgate((R)) ) and control (without agent). The specimens were immersed in cola drink for 5 min and 2 h in artificial saliva, 4x per day for 5 days. The agents were applied before the first erosive cycle. KNH values were obtained before and after the erosive challenge. The surface morphology was evaluated by AFM. anova, Tukey's, and T-Student tests were applied. RESULTS: After erosion, no significant difference was found for KNH among gel, nanophosphate, and varnish groups; however, they showed higher KNH than control group. Gel and nanophosphate paste showed a protective layer formation on enamel surface by AFM. CONCLUSIONS: The calcium nanophosphate paste showed similar protection against enamel erosion compared with high-concentrated fluoride agents, even containing lower fluoride concentration.