Treatment procedures
inferior alveolar nerve block, underfilling, pain
COLD, CAVITY, SMEAR LAYER
NaOCl solutions (1% and 0.5%) were prepared by diluting 5% NaOCl solution (Chloran). To prepare NaOCl solution at 40°C, a 10‐mL syringe was filled with NaOCl solution at room temperature and heated to 40°C using syringe heaters (Alfa). A calibrated electric thermometer (SBG) was used to measure the temperature of each syringe. To prepare NaOCl at 2.5°C, a 10‐mL syringe was filled with NaOCl solution at room temperature and placed in a refrigerator at 2.5°C. A calibrated electric thermometer (SBG) was used to measure the temperature of each syringe. For the blinding purpose, all the steps of NaOCl solution preparation were performed by a trained assistant who had no role in the clinical process. An insulating plastic cover was used on the syringes to prevent the researcher from feeling the temperature of irrigation solutions.Patients received two cartridges of 2% lidocaine with epinephrine (Darupakhsh) (1:80,000) for the inferior alveolar nerve block before starting root canal treatment. All the treatment steps were performed by A.S.M and after isolation with a rubber dam, followed by preparation of the access cavity, the working length was determined using a Root ZX apex locator (Morita Co.) and radiographically confirmed. In unsuccessful anesthesia, PDL and intrapulpal injections were used as complementary techniques. After preparing the root canals with hand instruments to at least #15 K‐file (Mani), Denco rotary files (Shenzhen Denco Medical) were used to prepare the root canals with a speed of 250–350 rpm and a torque of 1–2 Ncm. Apical patency was checked between each use of the rotary file with a K‐file #10 (Mani), and apical preparation was completed up to the F3 file. During instrumentation, the root canals were irrigated with 2 mL of NaOCl between each successive instrument (in group 1 with 1% solution at 22°C, in group 2 with 1% NaOCl solution at 40°C, in group 3 with 0.5% NaOCl solution at 22°C, in group 4 with 0.5% NaOCl solution at 40°C, in group 5 with 1% NaOCl solution at 2.5°C, and in group 6 with 0.5% NaOCl solution at 2.5°C). A 27‐G needle was inserted into the root canal (Avapezeshk) up to 2 mm shorter than the working length, and the root canals were flushed with upward and downward movements of the syringe with a rubber stop as a guide. The needle was repeatedly moved up and down during irrigation to prevent locking inside the root canals. To prevent NaOCl accidents, side‐vented flushing syringes were used passively and without getting stuck in the root canals. At the end of the root canal preparation process and before obturation, the smear layer was removed from the root canal wall using 3 mL of 17% ethylenediaminetetraacetic acid (Morvabon) and then with 5 mL of normal saline solution.In the same session, the root canals were dried using paper points (Meta Biomed Co.) and then obturated with gutta‐percha (Meta Biomed Co.) and AH26 sealer (Dentsply Maillefer) using the cold lateral compaction technique. Zonalin (Golchai) temporary restoration was placed. After obturating the root canals, a periapical radiograph was taken for any procedural errors such as underfilling, overfilling, voids, etc. Each patient received a pack containing 10 tablets of ibuprofen (400 mg) (Dana) to take for persistent pain after treatment.