# Effect of Different Sodium Hypochlorite Concentrations on Post Endodontic Pain: A Systematic Review and Meta‐Analysis of Randomized Controlled Trials

## TL;DR

This study reviews whether different concentrations of sodium hypochlorite affect post-root canal pain, finding no significant difference but suggesting lower concentrations may cause less pain.

## Contribution

The study provides a systematic review and meta-analysis comparing low and high sodium hypochlorite concentrations for post-endodontic pain outcomes.

## Key findings

- No significant difference in post-operative pain between low (<5%) and high (≥5%) sodium hypochlorite concentrations.
- Lower concentrations (<5%) were associated with less pain in some studies, though not consistently significant.
- Only one study reported higher pain with lower sodium hypochlorite concentrations.

## Abstract

The aim of the present systematic review and meta‐analysis was to evaluate the effect of different concentrations of sodium hypochlorite (NaOCl) on post‐operative pain following root canal treatment.

The current study was conducted according to PRISMA guidelines and registered on PROSPERO (CRD42023451576). The research question was formulated according to PICO strategy and aimed at determining if different concentrations of NaOCl would have influenced post‐operative pain in adults following endodontic treatments. A comprehensive literature search was performed manually and through multiple electronic databases, using predefined keywords and MeSH terms. Randomized controlled trials (RCTs) comparing different NaOCl concentrations (< 5% vs. ≥ 5%) and reporting post‐operative pain in adults were included. The risk of bias was assessed using the Cochrane RoB 2 tool. Meta‐analyses were conducted for pain occurrence at 24, 48, and 72 h post‐treatment.

Seven RCTs met the inclusion criteria and were included in the systematic review; moreover, four studies underwent quantitative evaluation (meta‐analysis). The results showed no statistically significant difference in post‐operative pain between low (< 5%) and high (≥ 5%) NaOCl concentrations at any time point. However, a low concentration of NaOCl seemed to be associated with less pain, significantly in 2 papers and not significantly in 4 articles out 7. Only one study reported the opposite trend.

Within the limitations of the present study, no significant differences in post‐endodontic pain were found between high and low NaOCl concentrations. However, concentrations < 5% might be associated with less pain incidence. Further well‐designed clinical trials with standardized methodologies are needed to provide more conclusive evidence.