Antibacterial Effect of Green Tea Extract on Streptococcus mutans and Enterococcus faecalis Isolated from Dental Plaque

Green tea polyphenols green tea is one important factor for inhibition of growth of oral bacteria. This study investigates the antibacterial effect of green tea extract on Enterococcus faecalis and Streptococcus mutans of dental plaques. A lot of 60 samples of dental plaques, the samples were placed in transport medium (TSB) and were then transported to the microbiology laboratory. The samples were cultured in blood agar medium, Mitis salivarius agar, bile esculin agar and were incubated in proximity of Co2 (5-10%) at 37 °C for 48 hours. After observing the colonies, the slides were prepared and were stained by Grams Method. To ensure the authentication and identification of microorganisms, common microbial and chemical tests were used. After determining the type of bacteria, antibiogram test was done and to determine bacterial sensitivity and resistance to green tea, sodium hypochlorite and chlorhexidine by Disc Diffiusion Agar according to CLSI (Clinical and Laboratory Standards Institute) guidelines. The data were analyzed by ANOVA and Tukey test (a=0.05) ANOVA test showed that diameter of growth inhibition of green tea was not so different from chlorhexidine for Streptococcus mutans, (P=0.305) but was significantly less than sodium hypochlorite (P=0.0001) and also the inhibitory effect of sodium hypochlorite was significantly higher than chlorhexidine (P=0.038). In Enterococcus faecalis, sodium hypochlorite was more effective than green tea and chlorhexidine (P=0.0001) and chlorhrxidine effect was significantly greater than that of green tea (P=0.0001). Sodium hypochlorite had the highest inhibitory effect on growth of Streptococcus mutans and Enterococcus faecalis. Since there was no significant difference between inhibitory effect of green tea in Streptococcus mutans and chlorhexidine, using it as a mouth wash, could be a suitable alternadive way to prevent tooth decay