Comparison of the Antimicrobial Efficacy of Green Tea Extract With 1% Sodium Hypochlorite Against Enterococcus faecalis: An In Vitro Study

Residual microorganisms are the main cause of root canal treatment failure. Due to the occurrence of bacterial resistance against antibiotics and the side effects of these drugs, herbs that possess antimicrobial qualities are drawing more attention than before. The aim of this study was to compare different concentrations of green tea with 1% sodium hypochlorite with regard to their antimicrobial effects on Enterococcus faecalis. In this experimental study, extracts of green tea with four different concentrations (40, 80, 100 and 200 mg/mL) were prepared. E. faecalis was cultured on Mueller Hinton agar. Within each culture plate, a disc with one of the concentrations of green tea extract, a disc of 1% sodium hypochlorite, a disc of tetracycline as a positive control, and a disc of distilled water as a negative control was placed. After 48 hours, the mean of the inhibition zone diameter was compared by using one-way ANOVA. The mean of the inhibition zone diameter around the discs of green tea extract in all concentrations was significantly less than 1% sodium hypochlorite (P < 0.001). The antimicrobial effect increased in higher concentrations of extracts of green tea (P < 0.001). Although the antimicrobial effect increases in higher concentrations of extracts of green tea, 1% sodium hypochlorite has a greater antimicrobial effect on E. faecalis in comparison with extracts of green tea.