Methods
inferior alveolar nerve block, postoperative pain, pain, necrosis, tooth
SYMPTOMATIC APICAL PERIODONTITIS, POLAND, STERILE, CAVITY, NECROSIS, NECROTIC PULP, COLD
The present randomized superiority trial was registered in the Registry of Clinical Trials (IRCT20191104045331N1) on 27/10/2020, available at The trial patients were selected from those referred to the Endodontics Department of the School of Dentistry. The inclusion criteria consisted of participants aged 18–65 years that had restorable single-canal maxillary or mandibular premolar teeth with asymptomatic apical periodontitis (no sensitivity to percussion or palpation) and necrotic pulp confirmed using ENDO-FROST spray cold (Coltène-Whaledent, Langenau, Germany) and periapical radiography (periapical index of 3, 4, or 5) without any preoperative pain. The exclusion criteria included retreatment cases, teeth with a periapical index of 1 or 2, and patients taking an analgesic during the past 12 h.Initially, a total of 119 participants that required endodontic treatment were included in this randomized, single-blind, two-arm parallel, superiority trial. With a 2-sided alpha risk of 0.05, a sample size of 44 subjects in each group is a prerequisite to distinguish a significant difference of 0.5 (20%) in VAS score with a power of 80 [In each group, after the administration of an inferior alveolar nerve block using Lidocaine HCl 2% with Epinephrine 1:100000 (DarouPakhsh, Tehran, Iran), each tooth was isolated using a rubber dam (Sanctuary, Perak, Malaysia), and the access cavity was prepared. If the pulp was diagnosed with partial necrosis, the participant was excluded and replaced. Following coronal flaring by a #SX ProTaper Universal (Dentsply Sirona, Ballaigues, Switzerland), a Root ZX Apex Locator (Morita, Tokyo, Japan) was used to determine the working length (indicator reach 0.5 according to manual), which was confirmed by digital radiography (0.5 mm short of the radiographic apex). After the negotiation of canals with K-file #15 and 20 (Mani, Tochigi, Japan), canals were prepared by #S1, S2, F1, F2, and F3 ProTaper Universal rotary files using the crown-down technique. So, the apical preparation size for each group was 0.30 mm. Apical patency was maintained by using a K-file #10. Sodium hypochlorite 2.5% (Cerkamed, Stalowa Wola, Poland) was used for irrigation, and sterile saline (DarouPakhsh, Tehran, Iran) was used as the final irrigating solution using a 27-gauge side-vented needle (Ultradent, South Jordan, UT) which was placed in the apical third of the canal during irrigation (total quantity of 6 mL of sodium hypochlorite and 30 mL of sterile saline was used) [In the GP group, after checking the master apical cone with a digital periapical radiograph (Vatech, Gyeonggi-do, Korea), the root canals were filled with GP (Meta Biomed, Chungcheongbuk-do, Korea) and AH-26 sealer (Dentsply, Tulsa Dental, Tulsa, OK) using the traditional lateral compaction technique. Sealer was prepared with AH Plus Jet mixing syringe (Dentsply DeTrey, Konstanz, German) and placed on canal orifices with intra-oral tips (Dentsply DeTrey, Konstanz, German). Applying the Master-Point Technique, the wall of the canal was wet gently by counterclockwise rotation of the point.In the MTA group, the root canals were filled with an MTA apical filling followed by a coronal GP and sealer filling. ProRoot MTA powder (Dentsply Tulsa Dental, Tulsa, OK) was mixed with the liquid at a 3:1 ratio according to the manufacturer’s instructions. An MTA filling with 3–5 mm thickness was placed using a Map system (Produits Dentaires SA, Vevey, Switzerland) and packed using a plugger (Dentsply, Maillefer, Switzerland). After confirming the quality and length of MTA filling by radiographic, the remaining root canal was filled with GP and AH-26 sealer using the lateral compaction technique.At the end of the session, temporary restoration (Coltosol F, Altstatten, Switzerland) was applied and the final radiograph was obtained for each group; if the final root canal filling lengths exceeded the working length, the participant was excluded and replaced. Finally, the patients were referred to the Restorative Department for placement of the final restoration. The entire procedure was performed in a single-visit by a 5-year experienced practitioner (S.G) using 3.5x magnification. During each procedure, the participants were blinded to the obturation method. The flowchart of the experimental procedure is presented in Additional file 1: Figure To assess the severity of postoperative pain, the participants were instructed to rate their pain level 6, 12, 24, 48, and 72 h after treatment using a questionnaire containing a 10-point Visual Analog Scale (VAS). The questionnaires were then collected after three days by an investigator (S.G). The VAS was classified using the following scale [The data were fed into IBM SPSS Statistics, Version 20.0 (Armonk, NY: IBM Corp.). The independent t-test and chi-square test were used to compare the difference between the two groups in terms of age, gender, and tooth location. The Friedman test was used to compare pain intensity over time. The Mann-Whitney U test was run to compare pain levels between the groups, genders, and tooth locations. The significance level was set at 0.05.