Efficacy of stevioside sweetener on pH of plaque among young adults

BACKGROUND: Stevioside is a natural herbal sweetener extracted from Stevia rebaudiana. An in vitro study has proved the antibacterial efficacy of 0.2% Stevia aqueous solution against Streptococcus mutans and Lactobacillus acidophilus, and the present study was conducted to clinically evaluate the efficacy of Stevia leaf extract and Stevia product on plaque pH, when compared with sucrose solution. MATERIALS AND METHODS: A clinical trial was conducted among a sample of 22 undergraduate students who volunteered. After obtaining consent, students were instructed not to brush at night and not to use any mouth rinse during the course of the study. Baseline plaque pH was measured in situ using digital pH meter. Students were asked to rinse for 1 min with 0.2% aqueous solution of Stevia leaf extract and plaque pH was measured in situ at 4 time points (5, 10, 15, and 30 min) after each rinse. After a washout period of 2 days, 10% sucrose and 1% Stevia product solutions were similarly tested. Statistical analysis was performed using analysis of variance (ANOVA) test and repeated measures ANOVA. Tukey's HSD test was used to obtain multiple comparisons. The level of significance was set to be at P < 0.05. RESULTS: At 5, 10, 15, and 30 min, a significant difference in mean plaque pH values was observed between three test solutions (P < 0.000). Post hoc Tukey's HSD test showed that the difference in mean pH values between aqueous Stevia extract and sucrose and Stevia product and sucrose was highly significant (P < 0.000). CONCLUSION: Stevia leaf extract and commercially available Stevia product did not significantly affect plaque pH values, implying that two solutions are non-fermentable and do not support bacterial survival.