Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 22 0 2025 06 02 4610 4610 Elham Khoshbin Endodontics Department, Dental Research Center, Avicenna Institute of Clinical Sciences, Avicenna Health Research Institute, Hamadan University of Medical Sciences, Hamadan, Iran Forough Nikzad Endodontics Department, School of Dentistry, Kashan University of Medical Sciences, Kashan, Iran Mohammad Reza Arabestani Department of Medical Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran Maryam Farhdian Department of Biostatistics, School of Public Health and Research Center for Health Sciences, Hamadan University of Medical Sciences, Hamadan, Iran Hamed Karkehabadi Endodontics Department, Dental Research Center, Avicenna Institute of Clinical Sciences, Avicenna Health Research Institute, Hamadan University of Medical Sciences, Hamadan, Iran 2022 09 23 2023 10 11 Objectives: This study compared the antimicrobial effects of Endoseal MTA and AH Plus sealers on Enterococcus faecalis (E. faecalis) and Candida albicans (C. albicans) mature biofilms on dentin blocks. Materials and Methods: In this in vitro study, the root canals of 207 dentin blocks sectioned from the roots of extracted teeth were inoculated with E. faecalis and C. albicans, and incubated for 3 weeks. The specimens were evaluated in 12 groups (n=17) for random root canal filling with AH Plus, Endoseal MTA, or no sealer, and assessment after 24 hours and 2 weeks. Dentin chips were cultured on blood agar, and the colonies were counted. One random specimen from each group was assessed under a scanning electron microscope (SEM). Data were analyzed using the Kruskal-Wallis and Mann-Whitney tests with Bonferroni adjustment at 0.05 level of significance. Results: At 24 hours, Endoseal MTA significantly decreased the E. faecalis count compared with the positive control (P<0.008). At 2 weeks, the colony count of both microorganisms was significantly lower in the AH Plus group compared with the control group (P<0.008). The C. albicans colony count in the Endoseal MTA group was significantly lower than that in the control group at 2 weeks (P<0.008). AH Plus caused significantly greater reduction in C. albicans colony count at 2 weeks compared with Endoseal MTA (P<0.008). Conclusion: AH Plus showed a higher antimicrobial activity over time against both E. faecalis and C. albicans. Endoseal MTA only showed short-term antibacterial effect. https://fid.tums.ac.ir/index.php/fid/article/view/4610 https://fid.tums.ac.ir/index.php/fid/article/download/4610/2147