Cold Sodium Hypochlorite Irrigation Cut Postoperative Endodontic Pain Most

Edited by Dentaltown staff

Irrigating with chilled sodium hypochlorite throughout chemomechanical preparation produced the largest reduction in postoperative pain among four approaches tested in a randomized clinical trial published Aug. 22 in Clinical Oral Investigations.

The trial enrolled patients with mandibular premolars diagnosed with irreversible pulpitis and symptomatic apical periodontitis, assigning them to one of four groups. A control group received standard treatment. A second group received intraoral cryotherapy using ice-gel packs. A third received a final intracanal flush of saline chilled to 2 to 4 degrees Celsius for 10 minutes. A fourth received sodium hypochlorite at the same temperature throughout instrumentation.

Postoperative pain was measured on a visual analogue scale, and levels of the proinflammatory neuropeptide Substance P were measured from apical fluid samples using enzyme-linked immunosorbent assay.

The cold hypochlorite group showed a statistically significant reduction in postoperative pain at P less than .001. The ice-pack and cold-saline groups fell between that result and the control group, which recorded the highest pain scores throughout.

Substance P moved in a different direction. The cold-saline group showed the greatest decrease in Substance P and the largest change from before to after treatment, also at P less than .001. Cold hypochlorite produced intermediate reductions, while the ice-pack group performed comparably to the control.

Pain scores and Substance P levels correlated moderately to strongly at six hours after treatment.

The authors concluded that cryotherapy techniques reduce postoperative pain and modulate Substance P expression, with cold irrigants the more effective of the approaches tested, and wrote that the methods deserve wider use in endodontic practice.

Maram Farouk Obeid, Reem Mohammed Amr Sharaf, and Ibraheem Mohamed Ibraheem Hamza conducted the trial, which was registered at ClinicalTrials.gov under NCT07138365.

The abstract does not report how many patients were enrolled or how they were distributed across the four groups. The population was also narrowly drawn, limited to mandibular premolars with a single diagnosis, so the results describe a specific clinical scenario rather than endodontic pain management broadly.

Sources:
Clinical Oral Investigations, “Clinical and biochemical effects of cryotherapy protocols on mandibular premolars with symptomatic apical periodontitis: a randomized clinical trial,” published online Aug. 22, 2026: link.springer.com/10.1007/s00784-026-07073-6