AbstractThe aim of this research was to examine marginal adaptation of three root end filling materials mineral trioxide aggregate (MTA), Biodentine and amalgam. Ninety single‐rooted extracted human teeth of the maxillary intercanine sector were used in the study. After the endodontic treatment and retrograde preparation, teeth were divided into three groups, depending on the root‐end filling material. Teeth were cut in longitudinal manner. Measurements of the total width of the marginal gap in micrometers were performed using scanning electron microscopy. The results showed that MTA and Biodentine have better marginal adaptation compared to amalgam expressed through the mean value of the measured edge crack, however without significant difference (p > .05). Mean value of the measured edge crack in Group 1 (MTA) was 8.17 μm, in Group 2 (Biodentine) 8.53 μm, and in Group 3 (amalgam) 9.13 μm. All tested materials show a satisfactory degree of marginal adaptation, but MTA and Biodentine proved to be superior to amalgam.