Background and Aim: Oral infections and dental caries are considered as two serious public health problems, which inflict a costly burden on health care services worldwide, especially in the developing countries. The aim of this study was to evaluate the antibacterial activity of Iranian Licorice aqueous root extract on Lactobacillus Acidophilus in comparison with Chlorhexidine.

Materials and Methods: In this in-vitro experimental study, we evaluated the antibacterial activity of Licorice aqueous root extract and Chlorhexidine against Lactobacillus Acidophilus using Disk Diffusion Method, determining the Minimum Inhibitory Concentration (MIC) by Broth Micro & Macro Dilution Methods and the Minimum Bactericidal Concentration (MBC) by Agar Dilution Method. Research was repeated 3 times and data were analyzed by ANOVA test. The P value of ≤ 0.01 was considered as the level of significance.

Results: Chlorhexidine showed significantly higher levels of antibacterial activity against Lactobacillus Acidophilus in comparison with Licorice aqueous root extract (P < 0.01).

Conclusion: Although Licorice aqueous root extract is beneficial, Chlorhexidine is more efficient in the prevention of dental caries and oral infections.