Aim:The aim of this study was to investigate the inclusion of silver nanoparticles (Ag NPs) in the mineral trioxide aggregate (MTA) composition to know which changes will result in the radiopacity of the material. Materials and methods:The experiment was performed according to the American National Standard Institute/American Dental Association specification no. 57/2000 and ISO 6876/2001. Five plates with five holes measuring 1 mm in depth and 5 mm in internal diameter were filled according to the different experimental groups as follows: white mineral trioxide aggregate (WMTA) + NP50 -W MTA with liquid Ag NP 50 ppm, WMTA + NP30 -W MTA with liquid Ag NP 30 ppm, WMTA + NP22 -W MTA with liquid Ag NP 22 ppm, WMTA + NPP -white MTA with liquid Ag NP and powder 1%, WMTA (control). After filling the plates, they were kept in an incubator at 37°C in relative humidity for setting. Each sample was positioned along an aluminum step-wedge placed above the Opteo digital sensor system. The image was divided into four quadrants, and three readings were made for each quadrant to render the average of each quadrant. The resulting data were submitted to Kruskal-Wallis and Dunn's tests. Results:The results showed statistically significant differences between WMTA + NP30, WMTA + NP22, and WMTA + NPP interactions compared with WMTA (control) (p < 0.05). The radiopacity was in descending order: WMTA + NPP, WMTA + NP22, WMTA + NP30, MTA + NP50, and WMTA. Conclusion:Silver NPs changed the radiopacity of WMTA, being more evident in WMTA + NP powder at 1% weight.Clinical significance: The low radiopacity of MTA makes it difficult for any radiographic observation. The Ag NPs appear as an alternative, being an excellent radiopacifier as they have excellent antimicrobial property and relatively low toxicity.