The effect of tea on surface loss of the dental enamel under erosive challenge in vitro

Aim: To investigate the effect of black and green tea on surface loss (progression) of dental enamel under erosive challenge in vitro. Materials and Methods: A total of 150 bovine enamel slabs were subjected to a pH cycling regime with erosive challenges (0.3% citric acid, pH 2.6). The slabs were randomly assigned to 5 treatment groups: black and green tea (≈ 5.0 ppm F), black tea with milk, black tea with citric acid 1.0% pH (3.6) and fluoride-free water (control). Within 28 days of the pH cycling period, the slabs were exposed five times for 2 minutes’ periods in erosive challenge citric acid plus three times for 10 minutes in each of 5 treatment groups. Throughout the cycling period the slabs were stored at 37 oC in artificial saliva in an incubator. The slabs were analysed with the Profilometer to measure the amount of surface loss at days 7, 14, 21 and 28 of the pH cycling period. Results: Data showed normal distribution by Kolmogrov-Smirnov test and the overall appearance of Q-Q plot for the variables. The results showed that the mean enamel surface loss for each group increased over time. One-way ANOVA test with Bonferroni correction was used to compare between groups. There was a significant difference in enamel surface loss after 28 days erosive challenge when comparing between the fluoride free-water (control) group with black tea and black tea infusion with additions of milk or citric acid groups (p<0.05), but there was no difference in comparison with green tea group. There was no difference on enamel surface loss between black tea and green tea, and black tea infusion with citric acid groups after 28 days of erosive challenge. However, the black tea with milk group showed a significant less enamel surface loss (p<0.05). Conclusions: All black tea groups with or without additions (citric acid or milk) were significantly beneficial with respect to enamel surface loss under erosive challenge. Furthermore, black tea infusion with addition of milk provides the greatest protection against tooth surface loss in our model.