Comparative evaluation of various herbal extracts on biofilms of Streptococcus mutans and Scardovia wiggsiae: An in vitro study

Background Owing to their strong antimicrobial properties, Helichrysum arenarium (HA), Anzer thyme (AT), and Stevia rebaudiana (SR) have been commonly used in medicine. Aim This study aimed to evaluate antimicrobial activities of HA, AT, and SR against S. mutans and S. wiggsiae in biofilms formed on primary teeth. Design Fifty enamel samples were divided into two groups: mono-species biofilm and two-species biofilm. Each biofilm group was divided into five subgroups (n = 5): group 1, HA; group 2, AT; group 3, SR; group 4, CHX (positive control); and group 5, distilled water (negative control). Minimum inhibitory concentration and minimum bactericidal concentration were determined. The number of viable microorganisms was counted. The presence of microorganisms was examined using a scanning electron microscope, and mineral analysis was performed using energy-dispersive X-ray analysis. Results In the mono-species biofilm, CHX was significantly more effective against S. mutans than other groups (p < .001). Furthermore, HA, AT, and SR groups showed significantly lower colony counts of S. mutans than distilled water (p < .05). In the two-species biofilm group, AT, SR, and CHX were significantly more effective against S. wiggsiae than distilled water (p < .05). Conclusions HA, AT, and SR have been suggested as effective natural alternatives to CHX against cariogenic bacteria