Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 21 0 2024 01 10 1 7 Maryam Gharechahi Dental Materials Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran Mohammad hossein Kafi Department of Endodontics, School of Dentistry, Rafsanjan University of Medical Sciences, Rafsanjan, Iran Maryam Javidi Dental Materials Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran Niloufar Jafari Department of Operative Dentistry, School of Dentistry, Rafsanjan University of Medical Sciences, Rafsanjan, Iran Maryam Joibary Moghaddam Dental Materials Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran 2021 03 14 2022 05 31 Objectives: Endodontic treatment of immature teeth poses a significant challenge, especially in achieving a proper seal using traditional obturation methods. Revascularization presents itself as an alternative approach to this problem, and the application of triple antibiotic paste (TAP) has been suggested as a means to achieve disinfection during the procedure. This study aims to compare the antibacterial properties of three different antibiotic combinations to assess their effectiveness on root canal disinfection. Materials and Methods: Eighty samples were employed to assess the impact of three antibiotic combinations on Enterococcus faecalis, Escherichia coli, Streptococcus mutans, and a combination thereof. The antibiotics included metronidazole, ciprofloxacin, and cefaclor (CCM), the commonly used TAP, and a double antibiotic paste (DAP) composed of metronidazole and ciprofloxacin. Dentin shavings collected using Gates-Glidden drills were placed in microtubes containing a 2ml standard bacterial suspension. Microtube contents were diluted and cultured on BHI agar plates, with colony counts calculated based on dentine shavings' weight in CFU/mg. Kruskal-Wallis and Dunn’s post-hoc tests were used for statistical analysis and P<0.05 was considered significant. Results: A significant difference in mean CFU was observed among all bacterial groups (P<0.05). Dunn's post-hoc analysis showed a significant difference only between the control group (methylcellulose) and the other antibiotic groups. There was no significant difference between the other antibiotic groups in two-by-two comparisons. Conclusion: There was no significant difference in the antimicrobial properties of DAP, TAP and CCM. Therefore, DAP and CCM may be used during regenerative treatment. https://fid.tums.ac.ir/index.php/fid/article/view/3996 https://fid.tums.ac.ir/index.php/fid/article/download/3996/2022