Abstract
Background: The current recommendations for the apical preparation diameter, one of the most important mechanical imperatives in the apical third preparation, are to preserve the apical foramen in its original position along with its narrowest diameter to avoid any complication such as tearing, zipping, or transport of the foramen. The aim of our study was to see the correlation between apical seal and apical preparation diameter. Materials and Methods: In total, 90 extracted maxillary incisors were randomly allocated into three groups of 30 teeth each according to the apical preparation size: Group 1: finishing file F1 corresponding to size 20 reached the working length, Group 2: prepared up to size 30 corresponding to finishing file F3, and Group 3: prepared up to size 50 corresponding to finishing file F5. After the filling of the root canals, the teeth were isolated and immersed in a dye solution, then cut longitudinally, photographed, and the dye penetration were calculated using a computer software. Results: Comparison of the three different apical preparation sizes showed no statistically significant differences regarding the apical microleakage. Conclusion: The most important value of the dye penetration was observed in the group with the largest apical diameter.