haping is considered a crucial phase in root canal treatment because it is not only aimed at removing remaining pulp tissue, microorganisms, and debris but also creates the preconditions for effective irrigation and obturation. These tasks should be accomplished without altering the diameter and position of the apical foramen or excessively weakening the root in any part. The degree of transportation essentially depends on the severity of root canal curvature and on the flexibility and geometry of the instruments. Nickel-titanium (NiTi) files allow more centered preparations as compared to stainless steel files because of their higher flexibility, especially in severely curved canals, even when increased apical preparation tapers and diameters are required

canal curvature, apical foramen transportation, preparation time, root canal preparation, rotary file systems, CBCT.