Working lengths of the 120 roots in the experimental groups were determined by subtracting 1 mm from the length at which the #10 K-file (Dentsply Maillefer, Ballaigues, Switzerland) first appeared at apical foramen. Then, the apical foramen of each canal was sealed with sticky wax to create a closed-end system.
Root canal preparation was initiated with glide path management by manipulating ProGlider instrument (tip size/taper: #16/.02) (Dentsply Sirona, York, PA, USA) at 300 rpm and a torque of 4.0 Ncm to full working length. Then, the root canals were shaped by using ProTaper Gold NiTi instruments to F4 (tip sizes/taper: #40/0.06) (Dentsply Sirona). The files were powered by an electric motor (X-Smart plus, Dentsply Maillefer) with the manufacturer’s recommendations. Throughout the period, 2 mL 5.25% NaOCl (except for the MTAD groups, where 2 mL 1.3% NaOCl was used) (all manufactured by Wuhan Longly Biotechnology Co., Ltd., Wuhan, China) was used as an intracanal irrigant solution by using a 30-G side-vented needle (Navitip, Ultradent, South Jordan, UT, USA) after each instrument. After the preparation, the canals were irrigated with 5 mL distilled water to rinse out NaOCl and dried with #40 paper points (Dentsply Maillefer).
Root canal preparation was initiated with glide path management by manipulating ProGlider instrument (tip size/taper: #16/.02) (Dentsply Sirona, York, PA, USA) at 300 rpm and a torque of 4.0 Ncm to full working length. Then, the root canals were shaped by using ProTaper Gold NiTi instruments to F4 (tip sizes/taper: #40/0.06) (Dentsply Sirona). The files were powered by an electric motor (X-Smart plus, Dentsply Maillefer) with the manufacturer’s recommendations. Throughout the period, 2 mL 5.25% NaOCl (except for the MTAD groups, where 2 mL 1.3% NaOCl was used) (all manufactured by Wuhan Longly Biotechnology Co., Ltd., Wuhan, China) was used as an intracanal irrigant solution by using a 30-G side-vented needle (Navitip, Ultradent, South Jordan, UT, USA) after each instrument. After the preparation, the canals were irrigated with 5 mL distilled water to rinse out NaOCl and dried with #40 paper points (Dentsply Maillefer).
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