Effect of iron on the dissolution of bovine enamel powder in vitro by carbonated beverages

Abstract Objectives The aim of this study was to evaluate, in vitro , the effect of iron on the dissolution of bovine enamel powder, when added to two carbonated beverages. Design Powdered enamel was produced by griding enamel fragments of bovine incisor in a steel pestle and mortar. Particles between 75 and 106 μm were selected using appropriated meshes. At time zero, the carbonated beverage (Coke® or Sprite Zero® ) was added to powdered enamel (1 mg enamel powder/10 μL of beverage) and vortexed for 30 s. The sample was immediately centrifuged (11,000 rpm) for 30 s and the supernatant was removed at 1 min 40 s. This procedure was repeated five times with the beverage containing increasing ferrous sulphate concentrations (1.25, 2.5, 5, 10, 15, 30 and 60 mmol/L). The phosphate released in the medium was analysed spectrophotometrically. Data were analysed using ANOVA and Tukey's test ( p < 0.05). Results When iron at 30 and 60 mmol/L was added to Coke® , a significant reduction in the dissolution of powdered enamel was observed when compared to control (11 and 17%, respectively), while lower iron concentrations did not have any effect on enamel powder dissolution. Regarding Sprite Zero® , iron concentrations up to 10 mmol/L had no significant effect, while higher concentrations significantly increased enamel powder dissolution. Conclusions The results suggest that iron can interfere with the dissolution of dental enamel powder in the presence of acidic beverages and the type of acid in these beverages seems to modulate this effect.