Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 21 0 2024 02 13 1 7 EN Sholeh Ghabraei Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Hadi Assadian Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Hassan Razmi Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Mohammad Saeid Sheikhrezaei DDs, MSc, Associate Professor, Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences (TUMS), Tehran, Iran Sedigheh Khedma Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Nazanin Chitsaz Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Zahra Mohammadi Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Faranak Noori Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran 2021 10 12 2022 08 19 Objectives: Antibacterial activity against endodontic pathogens is a desirable feature for root canal sealers. The objective of this study was to compare the antibacterial effect of three resin-based endodontic sealers (AH26, Adseal, and Beta RCS) against Enterococcus faecalis in vitro. Materials and Methods: The antibacterial properties of the sealers were assessed against E. faecalis using agar diffusion test (ADT) for fresh state (N=10) and direct contact test (DCT) for freshly-mixed and set states of the materials (N=10). In ADT, the diameter of the zones of inhibition was measured after 24h of contact. In DCT, the colony-forming units of the bacteria were counted after 30 minutes and 180 minutes of exposure. The results were analyzed with two-way ANOVA and independent sample t-test. P<0.05 was considered significant. Results: Regarding DCT results, all test materials indicated an antibacterial effect, both in freshly-mixed and set states. The highest antibacterial effect was related to Adseal, whereas the lowest was observed in Beta RCS. There was a significant difference between all study groups (different sealers, setting states, and contact times; P<0.001), except for freshly-mixed AH26 and Adseal at 180 minutes (P>0.05). According to ADT, AH26 and Adseal represented the widest and the smallest inhibition zones, respectively (P<0.001). Conclusion: Within the limitations of this in vitro study, AH26, Adseal, and Beta RCS showed antibacterial effects against E. faecalis in both freshly-mixed and set states. The antibacterial effect increased over time in all of the studied sealers. https://fid.tums.ac.ir/index.php/fid/article/view/4230