Hamadan University of Medical Sciences Avicenna Journal of Dental Research 2423-7582 13 1 2021 03 30 Short-term Effect of Four Root Filling Materials on the Flexural Stvrength of Human Root Dentin 18 22 10.34172/ajdr.2021.04 EN Hamed Karkehabadi https://orcid.org/0000-0002-1296-7361 Shahriar Shahriari Faraz Sedaghat Ebrahim Yarmohammadi Hadiseh Abbaspourrokni https://orcid.org/0000-0003-4713-4762 Journal Article 10.34172/ajdr.2021.04 2020 12 08 2021 03 17 Background: This study aimed to assess the effects of calcium hydroxide, Biodentine, calcium-enriched mixture (CEM) cement, and mineral trioxide aggregate (MTA) on root dentin flexural strength after a 30-day exposure period. Methods: This in vitro experimental study evaluated 25 freshly extracted sound human incisors with no caries or restorations. The apical 5 mm and the coronal two-thirds of the crowns were cut such that all samples had 10 mm length. Dentin samples (n=20 in each group) were then exposed to 2 mm thickness of calcium hydroxide, Biodentine, CEM cement, MTA, or saline (control) in petri dishes for 30 days. Finally, dentin samples were subjected to a three-point bending test after the intervention, and the flexural strength data were analyzed using one-way ANOVA, Tukey’s test, and t test. Results: Thirty-day exposure to all four biomaterials decreased the flexural strength of root dentin (P<0.05). The four groups were significantly different in terms of the flexural strength of root dentin (P=0.001). The flexural strength of root dentin was significantly lower following exposure to calcium hydroxide (P=0.003), Biodentine (P=0.011), CEM cement (P=0.001), and MTA (P=0.007) compared to saline. The reduction in strength following exposure to calcium hydroxide was higher than that in Biodentine, CEM cement, and MTA groups (P<0.05) while the latter three were not significantly different in this respect (P>0.05). Conclusions: In general, all four tested biomaterials decrease the dentin strength although this reduction is more prominent by calcium hydroxide.