The purpose of this study was to evaluate effect of cryotreated and warm sodium hypochlorite (NaOCl) on post-operative pain in patients with symptomatic irreversible pulpitis and symptomatic apical periodontitis.


Sixty-six individuals with pre-operative pain scores of ≥ 54mm on the Heft Parker Visual Analogue Pain Scale (HP-VAS) diagnosed with symptomatic irreversible pulpitis and symptomatic apical periodontitis as per the AAE guidelines in mandibular molars were included. The preparation of the access, and the root canals were instrumented and irrigated in accordance with a standard protocol. Based on the temperature of the final irrigant, the root canals were then randomly assigned to three groups and 3% NaOCl was irrigated: Control (at 25°C), cold NaOCl (2°C) and warm NaOCl (60°C) (n = 22/group). Root canal treatment was completed at the same visit. Pre- and post-operative pain assessment at 6, 24, 48, and 72 hours was conducted using HP-VAS, and analgesic consumption was noted. Suitable statistical tests were used to analyze the data.


In comparison to the other two groups, cold NaOCl group had a lower HP-VAS score at all follow-up intervals. Between groups, there was a statistically significant difference in post-operative pain scores at 6 and 72 hours (p < 0.05). None of the subjects experienced any postoperative discomfort at 72 hours in the control and cold NaOCl group.


Patients treated with cold NaOCl as the final irrigant experienced significantly lesser post-operative pain at 6 hours when compared to room temperature and warm NaOCl.

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