Comparison of the Antimicrobial Effect of Pomegranate Seed Extract with MI Fluoride Varnish and Their Synergistic Effects against Cariogenic Bacteria (Streptococcus mutans and Lactobacillus acidophilus)-an in-Vitro Study

Background and purpose: The antibacterial properties of pomegranate have been investigated in numerous studies. The aim of this study was to compare the antimicrobial effect of pomegranate seed extract (PSE) with Minnimally Invasive (MI) fluoride varnish and also to investigate their synergistic effect on the caries-causing bacteria Streptococcus mutans and Lactobacillus acidophilus bacteria. Materials and methods: In this in-vitro study, the antibacterial properties and the minimum inhibitory and bactericidal concentrations (MIC and MBC, respectively) of the the compounds were investigated using the disk agar diffusion test (growth inhibition halo) and the micro broth dilution test. The antibacterial activity of the methanolic extracts was studied in 5 groups: PSE, PSE and varnish, MI varnish, positive control (ampicillin and erythromycin) and negative control (sterile physiological serum). The data were analyzed using SPSS ver22 software. Results: The largest diameter of growth inhibition in S. mutans and L. acidophilus was observed in the combination of two extracts (12±0.22mm) and varnish (12±1.22mm), respectively, while the smallest diameters were recorded in PSE (8.0±1.0mm and 4.0±1.5mm, respectively). Varnish showed the lowest MICs and MBCs for both types of bacteria tested. PSE and varnish showed similar results in inhibiting the growth of S. mutans (P=0.588); however, the simultaneous use of two extracts showed significant synergistic effects (P<0.05). Conclusion: The MI varnish has a more favorable effect than the other groups studied, and a lower concentration is required to inhibit the growth of two bacterial species. However, high concentrations of PSE, with and without fluoride varnish, can be used against Streptococcus mutans.