Evaluation of pH-stat to assess the erosive potential of beverages

The erosive potential of acidic beverages should be assessed by a clinical relevant, fast and inexpensive method due to the high number of beverages available on the market. Objective: To evaluate the pH-stat analysis as an indicator of the erosive potential of beverages, by comparing it with other established methods. Methods: In phase 1, the erosive potential of 12 commercially available acidic beverages was tested by surface microhardness change (SMC) and surface loss (SL) of bovine enamel specimens after exposure times of 5, 10, 30, 60 and 120 min (n = 10). In phase 2, the pH-stat analysis of the beverages was performed (in triplicate) by setting the automatic titrator to the initial pH of each solution and by adding 25 mg of hydroxyapatite crystals, under agitation, at 25° C. The reaction of hydroxyapatite with the testing solution drove the pH increase, which was brought down by titration with 0.1N HCl. The final volume of the titrant added to each solution, after a 10-min reaction period was considered the response variable of this test. The titratable acidity and calcium (ionic and total), phosphate and fluoride concentrations of each solution was also analyzed. Correlation analyses of the pH-stat results with SMC and SL, for each demineralization time, and with the chemical properties of each beverage were performed. Results: The correlation of pH-stat with SMC and SL was very strong (r ³ 0.81) at all demineralization times tested, except at 5 and 10 min for SL, when it was strong (r ³ 0.60). pH-stat correlated very strongly with titratable acidity and calcium content (r ³ 0.73), strongly with phosphate (r = 0.64) and very weakly with fluoride (r = 0.13). Conclusion: The pH-stat method showed to be a promising in vitro method for the measurement of the erosive potential of acidic beverages.