Effect of Stevia Rebaudiana extracts on caries related variables

Methods:  In vitro; Three 10% test solutions containing stevioside, rebaudioside A and sucrose were prepared. A wild strain of SM was isolated and a 24-h-monospecific biofilm was obtained. A colorimetric technique (MTT assay), based on the reduction of a yellow tetrazolium salt to a purple formazan, was used to evaluate the biomass adherent. 90 μl of suspension were taken from each well and optical density was measured with a dual wave-length spectrophotometer in order to determine the bacterial counts. The means of the optical density (OD) was evaluated using oneway Anova. In vivo; On 20 healthy volunteers, plaque-pH was measured in three selected interproximal sites with a microtouch electrode. Each subjects rinsed for 1 minute with each test solution, allowing a 48 hour washout period. Plaque pH was measured at seven time points after each rinse.  Comparisons among the pH values for the three solutions were performed using repeated ANOVA.

Results: In vitro; Statistically significant difference was observed in SM growth between the Stevia extracts and sucrose (p<0.01). In vivo; No statistically significant differences were observed between pH values at baseline. Sucrose showed a statistically significant lower pH mean compared to Stevia extracts. (F=99.45 p< 0.01). pH returned to baseline after 45 minutes. 

Conclusions: Stevioside and rebaudioside A can be considered non-acidogenic in humans and could be efficiently used in dietary-based caries prevention strategies.