Evaluation of the Combination of Different Concentrations of Ethanolic Extracts of Mint (Menta longifolia) and Licorice (Glycyrrhiza glabra) on Oral Pathogens

Introduction: The present study aimed to investigate the antimicrobial effect of the ethanolic extracts of mint and licorice on Candida albicans and Streptococcus mutans. If the antibacterial and antifungal effects of these plants are observed, they can be introduced as effective plants against oral biofilm microorganisms to replace commercial drugs. They can also be considered cost-effective and innovative solutions to deal with caries. Materials & Methods: Two medicinal plants, mint and licorice, were extracted using ethanol as a solvent following their collection and drying. The antibacterial and antifungal properties of these extracts were evaluated using disc diffusion, well diffusion, and biofilm formation measurement methods on a total of 162 samples. In addition, the Kruskal-Wallis test was employed for statistical analysis, with data processed using SPSS (version 22). A significance level of 5% was maintained across all tests. Results: The analysis of the results in the disc and well diffusion indicated that the concentration of 100 mg/ml of licorice showed the strongest antibacterial effect among different concentrations, and Streptococcus mutans was more susceptible than Candida albicans. Moreover, the results of measuring the amount of biofilm formation demonstrated that the concentration of 100 mg/ml of licorice had the most substantial effect in inhibiting the biofilm of Streptococcus mutans and Candida albicans. Conclusion: Among the examined samples, a concentration of 100 mg/ml of licorice exhibited an antibacterial effect comparable to that of commercial chlorhexidine mouthwash. This finding suggests the potential for further research into the development of an herbal mouthwash based on this extract.