Erosive potentials of brewed teas

Abstract

Purpose: To measure the pH, titratable acidity, fluoride concentration and erosive potential of brewed teas.

Methods: Bag teas were purchased to represent black, green, citrus, fruity, and floral tea flavors from Tulsi, Bigelow, HyVee, Tazo, and Yogi brands and brewed (1 bag/240 ml) in boiling water for 3 minutes. The pH, titratable acidity, and fluoride concentrations were measured. Following these measurements, a representative tea from each flavor was selected for investigation of erosion potential. Six extracted human molars were randomly assigned to each tea. Teeth were painted with fingernail polish to expose a 1 x 4 mm window and then soaked in tea for a total of 25 hours with teas refreshed every 5 hours. Teeth were then sectioned using a microtome and photographed using a polarized light microscope. Lesion depths (i.e., eroded surfaces) were measured using Image Pro Plus software. Differences in physiochemical properties and lesion depths between beverages were investigated using one-way ANOVA with post-hoc Tukey's HSD test. Relationships among lesion depths and physiochemical properties were evaluated using the Pearson correlation test.

Results: pH, titratable acidity and fluoride concentrations differed between tea flavors (P < 0.05) and between brands (P < 0.05). Lesion depths produced by the citrus tea (83.1 +/- 10.3 microm) were greater than those produced by the fruity tea (56.5 +/- 6.1 microm); both teas produced greater depths than black (30.1 +/- 7.4 microm), floral (25.0 +/- 3.2 microm) or green (22.3 +/- 6.3 microm) teas (P < 0.05). pH (r = -0.96; P = 0.009) was inversely and titratable acidity (r = 0.97; P = 0.006) was positively associated with lesion depths.