Cariogenicity of Lippia Dulcis and Stevia Rebaudiana in Caries Model

Objectives: Dental caries result from the breakdown of tooth structure due to acids produced by bacteria like Streptococcus mutans. These acids form when sugars are metabolized, leading to enamel demineralization. Lippia dulcis, native to Mexico and Central America, has been used as a natural sweetener, while Stevia rebaudiana, a South American plant, contains non-nutritive sweet compounds called steviolglycosides. This study evaluates the anticariogenic potential of these natural sweeteners in a caries model.
Methods: The effect of Lippia dulcis and Stevia rebaudiana on S. mutans biofilm formation was assessed using the microdilution method. Bacterial cultures grown in Brain Heart Infusion (BHI) medium were adjusted to a 0.5 McFarland standard and incubated with plant extracts in 96-well plates at 37°C for 24 hours. Biofilms were washed with phosphate-buffered saline (PBS), fixed with methanol, and stained with 1% crystal violet. Absorbance was measured at 570 nm. Viable colony counts were determined by dispersing biofilm bacteria with PBS, followed by sonication, serial dilution, and plating on BHI agar.
Results: Treatment with Lippia dulcis and Stevia rebaudiana extracts significantly reduced S. mutans biofilm formation and colony counts. The control group showed 1x 10⁶CFU/mL. Sugarfree Green (Stevia rebaudiana) reduced counts to <20 CFU/mL, while Lippia dulcis extract achieved 1x10²CFU/mL. Nature Sugarfree (Stevia rebaudiana with higher sugar content) reduced counts to 1x10³CFU/mL, showing mild inhibition.
Conclusions: Natural sweeteners like Lippia dulcis and Stevia rebaudiana exhibit potential anticariogenic effects. Sugarfree Green showed superior antibacterial activity, while Lippia dulcis demonstrated notable effectiveness. Further studies on longer incubation and additional sweeteners are needed to confirm these findings.