Hamadan University of Medical Sciences Avicenna Journal of Dental Research 2423-7582 18 2 2026 06 30 In Vitro Comparison of the Cytotoxicity of Different Endodontic Sealers: AH Plus, AdSeal, Endoseal MTA, and GuttaFlow Bioseal 65 72 10.34172/ajdr.4569 EN Mehdi Dastorani https://orcid.org/0000-0001-9864-7934 Muhammad Javad Aliee Raheleh Halabian Mostafa Solati Mohammadsadegh Alemrajabi Journal Article 10.34172/ajdr.4569 2025 09 16 2025 12 11 Introduction: Endodontic sealers are essential components of root canal treatment and contribute to the sealing of the root canal system. Their cytotoxicity is an important factor in evaluating their biocompatibility. This study aimed to assess the cytotoxicity of four commonly used endodontic sealers, namely, AH Plus, AdSeal, Endoseal MTA, and GuttaFlow Bioseal against human gingival fibroblasts (HGFs). Methods: HGFs were exposed to the respective sealers in set form and in five different weights after sterilization. Then, the cytotoxicity of the sealers was evaluated after 1 day, 3 days, and 7 days using the methyl thiazolyl tetrazolium (MTT) assay. Ultimately, data were analyzed by repeated measures ANOVA followed by Tukey’s post hoc test. Results: After 24 hours, all sealers showed low cytotoxicity. However, sealers in 0.25 g and 0.5 g weights exhibited a marked reduction in cell viability (<30%) at 3 days and 7 days, indicating high cytotoxicity, while lighter weights (0.125 g, 0.1 g, and 0.08 g) demonstrated moderate-to-low cytotoxicity (30–70%). Moreover, AdSeal consistently displayed the highest cell viability, particularly at 0.08 g (around 70%), whereas AH Plus illustrated the lowest viability (approximately 5%) across all weights and time points. Conclusion: Among the tested sealers, AdSeal had the lowest cytotoxicity and the highest biocompatibility. Therefore, its use may promote faster periapical healing while reducing the risk of inflammatory complications compared with AH Plus.