Comparison of Antibacterial Effects of Heracleum persicum and Ziziphora tenuior L. Extracts, Calcium Hydroxide and Chlorhexidine on Enterococcus faecalis as Intracanal Medicaments in Root Canal Therapy – An In Vitro Study

BACKGROUND Given that periapical bacterial infections are considered as one of the causes of endodontic treatment failure, and biomechanical methods may not be able to eliminate bacteria resistant to endodontic treatment, including Enterococcus faecalis; therefore, this study was conducted to compare the antibacterial effects of Golpar and Kakoti extracts with calcium hydroxide and chlorhexidine against E. faecalis. METHODS At first, Heracleum persicum (Golpar) and Ziziphora tenuior L. (Kakoti) plants were extracted by ethanol solvent using the cold maceration method and a vacuum distillation apparatus. E. faecalis ATCC 29212 was used as the standard strain in all stages of the experiment. Antibiogram, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) tests were performed to evaluate the antibacterial activity of the prepared extracts. The anti-biofilm activity of the extracts was evaluated similar to MIC evaluation but with a longer incubation time and analyzed by ELISA at a wavelength of 492 nm. RESULTS The antibiogram test showed a growth inhibition zone diameter of 4 mm only for chlorhexidine. In addition, chlorhexidine exhibited the highest inhibitory and bactericidal activities in the MIC and MBC tests, respectively (MIC / MBC < 1.562 mg / mL). The MIC of Golpar, Kakoti, and Golpar + Kakoti extracts was determined to be 50 mg / mL. No significant inhibitory activity was observed for calcium hydroxide either alone or in combination with the plants' extracts. The MBC of Kakoti extract was 50 mg / mL, and the other compounds had an MBC greater than 100 mg / mL. CONCLUSIONS The present in vitro study showed that the highest inhibitory activity against E. faecalis was related to chlorhexidine; however, Golpar and Kakoti extracts at a concentration of 50 mg / mL exhibited a proper inhibitory activity compared to calcium hydroxide. Therefore, further studies are recommended to be conducted in the future. KEYWORDS Enterococcus faecalis, Ziziphora tenuior L., Heracleum persicum, Chlorhexidine, Calcium Hydroxide, Antibacterial effects.