fa Oral medicine Oral medicine Original article Original article <div style="text-align: justify;"><strong><span dir="LTR">Background and Aim: </span></strong><span dir="LTR">One of the main goals of endodontic treatments is to disinfect the root canal and dentin tubules. This study compared the antimicrobial effect of different concentrations of green tea extract with that of two common irrigants on Enterococcus faecalis (E. faecalis) in the root canal system.</span><br> <strong><span dir="LTR">Materials and Methods: </span></strong><span dir="LTR">In this experimental study on 124 single canal teeth, suspensions derived from the 24-hour culture of E. faecalis were inoculated into the canals, and the samples were incubated for two weeks. Then, the teeth were divided into six experimental groups (n=20) and two control groups (n=2). In the first group, 5% sodium hypochlorite (NaOCl), in the second group, 2% chlorhexidine gluconate (CHX), in the third group, 3.125% green tea extract, in the fourth group, 12.5% green tea extract, in the fifth group, 25% green tea extract, and in the sixth group, normal saline was used for root canal irrigation. The next day, the extracted liquid from vortexed dentin fragments was cultured, and the colony-forming units (CFU) were counted 48 hours later. Data were analyzed using Mann-U-Whitney test.</span><br> <strong><span dir="LTR">Results: </span></strong><span dir="LTR">The CFU count for NaOCl and CHX showed a statistically significant difference compared to different groups of green tea extract (P<0.001). The percentage of microorganism reduction was 100% with NaOCl, 98.9% with CHX,</span> <span dir="LTR">58.35% with 3.125% green tea, 8.1% with 12.5% green tea, 94.8% with 25% green tea, and 57.5% with normal saline.</span><br> <strong><span dir="LTR">Conclusion: </span></strong><span dir="LTR">The results of this study showed that green tea extract can be used in endodontic treatment as the final root canal irrigant considering its naturalness and its antimicrobial ability.</span></div> <br> <div></div> Root Canal Irrigants, green tea extract polyphenon E, Enterococcus faecalis, Sodium Hypochlorite, Chlorhexidine 32 36 http://jrdms.dentaliau.ac.ir/browse.php?a_code=A-10-359-1&slc_lang=fa&sid=1 B Dadresanfar 10031947532846009735 10031947532846009735 No Assistant Professor, Endodontics Dept, Faculty of Dentistry, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran M Vatanpour 10031947532846009736 10031947532846009736 No Assistant professor, Endodontics Dept,Faculty of Dentistry, Tehran Medical Sciences M Farahmand mona.farahmand87@gmail.com 10031947532846009737 10031947532846009737 Yes Postgraduate student, Orthodontics Dept, Faculty of Dentistry, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran S Taheri 10031947532846009738 10031947532846009738 No Dentist HR Mahaseni Aghdam 10031947532846009739 10031947532846009739 No Assistant professor, Oral and Maxillofacial Surgery and Implant Research Center, Dental Faculty, Tehran Medical Sciences