Fully erupted, human permanent maxillary anterior teeth, without caries or defects, were collected from local oral surgeons and stored in 10% formalin solution until use (Institutional Review Board#: 010617-005, University of New England, not human subject research). The teeth, extracted for treatment unrelated to this study, were placed under running water for 1 hour, then cleaned for this study with a scaler. Radiographs were taken to exclude teeth with multiple canals, cracks, fractures, resorption, caries, immature apices, or root curvature more than 10°.
Fifteen teeth were selected for NSRCT, and the working length was determined to be 1 mm short of the apex using a size 10 K-file. Canals were cleaned and shaped using ProTaper NEXT (Dentsply Sirona, Johnson City, TN, USA) NiTi rotary files with a ProMark torque-limited electric motor (Dentsply Sirona, Tulsa, OK, USA) to size X5 (#50/variable taper, a 6% taper in a 3 mm tip) using copious 2.5% NaOCl irrigation. The canals were dried by ProTaper NEXT absorbent points (Dentsply Sirona, Johnson City, TN, USA).
Fifteen teeth were selected for NSRCT, and the working length was determined to be 1 mm short of the apex using a size 10 K-file. Canals were cleaned and shaped using ProTaper NEXT (Dentsply Sirona, Johnson City, TN, USA) NiTi rotary files with a ProMark torque-limited electric motor (Dentsply Sirona, Tulsa, OK, USA) to size X5 (#50/variable taper, a 6% taper in a 3 mm tip) using copious 2.5% NaOCl irrigation. The canals were dried by ProTaper NEXT absorbent points (Dentsply Sirona, Johnson City, TN, USA).