AimThis randomized, prospective, double‐blind, clinical trial assessed the effect of 1.3% and 5.25% sodium hypochlorite (NaOCl) as irrigants on post‐endodontic pain and medication intake following root canal treatment of mandibular molars with nonvital pulps.MethodologyThree hundred and eight patients, each with one symptomatic or asymptomatic molar, were randomly assigned, using the permuted‐block method, into two equal groups according to NaOCl concentration: 1.3% or 5.25% (n = 154). For both groups, syringe irrigation was performed using a 27‐gauge needle advanced into the canal to a depth of 3 mm from the working length; 3 mL were used between every two consecutive instruments. All root canal treatments were carried out in two visits, with no intracanal medication, by trained postgraduate students. The canals were prepared using the ProTaper Universal rotary system during the first visit. In the second visit 7 days later, the same irrigant per group was used and the canal walls were reprepared with the final instrument before filling the canal using the modified single‐cone technique with an epoxy resin‐based sealer. Patients assessed their postoperative pain using a 0–10 numerical rating scale immediately after instrumentation, 3, 24, 48 h and 7 days after the first visit and immediately following root canal filling. The incidence of rescue medication intake (Sham or analgesic) was also recorded; patients received a sham capsule to be used first, but, if pain persisted, an analgesic was prescribed. Outcome data were analysed using Mann–Whitney U‐test, Friedman's test, Wilcoxon's rank test and chi‐square (χ2) test. Relative risk reduction (RRR) and its 95% confidence interval (CI) were calculated for binary data.ResultsThe incidence and intensity of postoperative pain were significantly lower with 1.3% NaOCl than 5.25% NaOCl at all time‐points (P < 0.05). Postoperative pain intensity exceeded preoperative pain at 3 and 24 h with 5.25% NaOCl only (P < 0.05). The RRR in pain incidence was 38% (95% CI: 17%, 54%) immediately after instrumentation, 41% (95% CI: 31%, 49%) at 3 h, 42% (95% CI: 32%, 51%) at 24 h, 59% (95% CI: 45%, 69%) at 48 h, 62% (95% CI: 27%, 80%) at 7 days and 81% (95% CI: 68%, 89%) after root filling. RRR was 38% (95% CI: 1%, 61%) for sham intake and 69% (95% CI: 37%, 85%) for analgesic intake.ConclusionsUsing 1.3% NaOCl was associated with less intense and less frequent post‐endodontic pain than 5.25% NaOCl in mandibular molars with nonvital pulps treated in two visits. The incidence of pain was reduced by up to 60% within the week post‐instrumentation and 80% after root canal filling and the rescue analgesic intake by about 70% on using 1.3% NaOCl compared to 5.25% NaOCl.

AimThis randomized, prospective, controlled trial assessed the effect of occlusal reduction on post‐treatment endodontic pain and medication intake following root canal treatment of mandibular posterior teeth with symptomatic irreversible pulpitis with sensitivity to percussion treated in two visits.MethodologyThree hundred and eight patients were randomly assigned into two equal groups according to whether occlusal reduction was done or not (n = 154). For all patients, root canal treatment was carried out in two visits without intracanal medication. Patients assessed their pain using the 0–10 numerical rating scale (NRS) 6, 12, 24 and 48 h after the first visit (post‐instrumentation) and 6 and 12 h following root canal filling (post‐obturation). Patients, also, recorded their medication intake (sham or analgesic), post‐instrumentation and post‐obturation; patients initially received a sham capsule, but, if pain persisted, an analgesic was prescribed. Data were analysed using Mann–Whitney U‐test, Friedman’s test, Wilcoxon’s rank test and chi‐square (χ2) test. The relative risk (RR) and its 95% confidence interval (CI) were calculated for binary data.ResultsOcclusal reduction was associated with lower pain intensity than no occlusal reduction at 12 and 24 h post‐instrumentation (P < 0.05). Pain intensity significantly and gradually decreased with both groups at all post‐instrumentation and post‐obturation time‐points compared to preoperative pain (P < 0.05). The RR of moderate‐to‐severe pain was 0.61 (95% CI: 0.41, 0.91) 12 h post‐instrumentation, and the RR of pain incidence, regardless of its level, was 0.75 (95% CI: 0.61, 0.92) 24 h post‐instrumentation. There was no significant difference in medication intake (sham or analgesic) between groups (P > 0.05).ConclusionsOcclusal reduction was effective in reducing the intensity of postoperative pain 12 h and 24 h after root canal instrumentation in the first visit in patients with symptomatic irreversible pulpitis with sensitivity to percussion. Occlusal reduction lowered the risk of moderate‐to‐severe pain by about 40% 12 h post‐instrumentation and the overall risk of pain by 25% 24 h post‐instrumentation; yet, it did not affect medication intake.

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