Estimated erosive potential depends on exposure time

Objectives: Evaluate erosive potential of beverages, using exposure times from 3 to 30 min, and to analyse the relationship between erosion and several drink parameters. Methods: pH, calcium, phosphate and fluoride concentration, saturation, titratable-acidity to pH 5.5 and the viscosity of sixteen beverages were measured or calculated. Enamel samples (N = 90) were serially exposed to 1 ml of the beverages for 3, 6, 9, 15 and 30 min and erosion was measured as the loss of calcium to the beverage. Rate of erosion per min was calculated by linear curve fitting using all exposure times. Linear regression analysis was performed to determine the correlation between erosion and the drink parameters. A limited multivariate analysis was performed for the outcome parameter with the highest univariate correlations (erosion per minute) and 4 drink variables. Results: A negative relationship was observed only for pH for all exposure times. Only for erosion per min a significant relationship with pH and saturation was found. In a model for erosion per min using only saturation, fluoride concentration, titratable acidity and viscosity, both saturation and viscosity were shown to have a significant effect (p = 0.01 and p = 0.05, respectively). Conclusion: Exposure times between 3 and 30 min result in very different estimates of erosive potential. There is no sound theoretical ground for preferring one or other exposure time/outcome as being more clinically relevant. Clinical relevance: This study shows that effect of the choice of study methodology on the measurement of erosive potential of beverages is large.