Amount of apically extruded debris of three different rotary instruments with design modification

Background: To determine the amount of apically extruded debris during root canal preparation with of DentsplyProTaper Universal (PTU), ProTaper Gold (PTG), and ProTaper Next (PTN) nickel titanium (NiTi) rotary files was evaluated in comparision with simulated files with same design and our study design. Methods: For PTU and PTG study design modification is to leave the apical 8 mm of S1 and the apical 3 mm of S2 as un-milled, F1 only the apical 5 mm would have cutting blades. For PTN is to leave the apical 8 mm of X1and, while for X2 is to leave the coronal 8 mm as un-milled. Ninety human mandibular second premolar teeth were decoronated to a 15mm length, an apparatus with minor modifications of the Myers and Montgomery experimental model was used, after canal preparation was stored in an incubator in order for water evaporation leaving only the extruded debris, then the vials were transmitted to the electrical balance for re-weighing. Conclusions: Leaving the portion of the file which supposes not to make canal preparation blank (without flutes) decreases the amount of debris extrusion in all protaper systems