A Comparison of Niobium with Other Radiopacifying Agents in Endodontic Cements: A Systematic Review of Physicochemical Properties

This systematic review evaluated the use of niobium as a radiopacifying agent in endodontic cements compared with other radiopacifiers. This review was conducted in accordance with the PRISMA 2020 guidelines (OSF registration). The PICO strategy defined the population as endodontic cements, the intervention as niobium-based formulations, the comparison as other radiopacifying agents, and the outcome as physicochemical properties. Six databases and the gray literature were searched up to December 2025, and the risk of bias was assessed using the JBI Critical Appraisal Checklist for Experimental Studies. A total of 1273 studies were identified, of which 10 were included in the review. Seven of the included studies evaluated radiopacity, showing that Nb-containing cements exhibited values equal to or lower than those containing other radiopacifying agents but still meeting ISO/ADA standards. Seven studies analyzed pH, which remained alkaline and was not influenced by Nb. Five studies investigated setting time, with no differences compared with other radiopacifiers. Studies assessing solubility showed conflicting results, reporting increases, reductions, or no differences compared with zirconium. Overall, the included studies presented a low risk of bias. In conclusion, niobium demonstrated physicochemical properties comparable to those of other radiopacifiers used in endodontic cements. However, further studies are needed to evaluate its influence on the setting time and solubility of materials.