Comparative Antimicrobial Effects of Lemon Verbena Extracts and Chlorhexidine on Cariogenic Bacteria

Background: Caries is a type of oral bacterial infectious disease. The two species responsible for the initiation of human dental caries include Streptococcus mutans and Streptococcus sobrinus. Lactobacillus species have also been observed in the secondary pathogenesis of caries. The antimicrobial properties of herbs, which do not affect the natural flora of the oral cavity, make them a suitable alternative to chemicals. Objectives: Due to the lack of studies and evidence on the antibacterial effect of the Aloysia citriodora on caries-causing bacteria and the absence of a research on different types of extracts of this herb, further tests were conducted in the present study.  Methods: In this comparative laboratory study, after preparing and extracting A. citriodora and obtaining its essential oil with a Cloninger machine, different concentrations were prepared. Then, zone of inhibition (ZOI) and minimum inhibitory concentration (MIC) tests were performed on S. mutans, S. sobrinus, and Lactobacillus casei. These tests were also performed on ۰.۱۲% chlorhexidine. Data were reported as Mean±SEM. The Kruskal-Wallis test was used to compare the ZOI diameters among different mouthwashes. Results: The greatest antibacterial effect of A. citriodora was related to the essential oil, followed by the hydroalcoholic, aqueous, and hexane extracts, respectively. In general, based on mean concentrations, S. mutans (P<۰.۰۰۱) and L. casei (P<۰.۰۰۱) were the most susceptible bacteria to chlorhexidine, while S. sobrinus (P<۰.۰۰۱) was most susceptible to the essential oil. The Kruskal-Wallis test showed a significant difference between the different extracts, essential oils, and mouthwash groups at all concentrations. Conclusion: If the results of the present study are confirmed by further studies, the essential oil as well as aqueous and hydroalcoholic extracts of A. citriodora can be used in the formulation of mouthwashes and toothpastes to combat caries-causing bacteria.

کلیدواژه ها:

Antimicrobial agents ، Streptococcus mutans ، Streptococcus sobrinus ، Lactobacillus casei ، Plant extracts