Sodium hypochlorite and chlorhexidine used as root canal irrigants had similar low postoperative pain rates

shutterstock_2296216-root canal xray

Clean, shape and fill is a well-known mantra for root canal treatment (RoCT) and the use of irrigating solutions is an important element of the process. The aim of this study was to compare the degree of postoperative pain after single-visit RoCT when using two separate irrigation solutions.

Patients with a diagnosis of chronic apical periodontitis with peri-radicular bone loss and apical patency requiring RoCT of a single tooth were randomised to the use of either 5.25% sodium hypochlorite NaOCl (n= 63) or 2% Chlorhexidine (CHX) and saline (n=63) as irrigants. Patients who had received antibiotics, anti-inflammatories or analgesics for at least 1 week before the study were excluded. Treatment was conducted under rubber dam.  The main outcome was post-operative pain assessed at 24, 48 and 72 hours and 7 days using a questionnaire.

  • There were no significant differences between the 2 groups in terms of postoperative pain at any time point
  • No patients reported severe pain at any stage.
  • Moderate pain was reported by 3% of patients (2/63 in each group) after 24 hours and by no patients beyond 24 hours, regardless of the irrigant used.
  • Mild pain was reported by 19% [12/63] of patients in the NaOCl group and 16% [10/63] in the CLX group at 24 hours. However it diminished to 10% [6/63] in the NaOCl group and 11% [7/63] in the CLX group at 48 hours and to 3% [2/63] in both groups at 72 hours and by 2% [1/63] in both groups at 7 days).

The authors concluded

Both of the irrigants tested in this study (5.25% NaOCl and 2% CHX gel with saline) were associated with low rates of postoperative pain among patients undergoing single-visit endodontic treatment for chronic apical periodontitis with pulp necrosis.


While the study does not show any difference between the two groups no power calculation was presented  and with the low rates of post-operative pain the study may not have been adequately powered to show a difference between the two agents.


Almeida G, Marques E, DDS, MSc; De Martin AS, DDS, MSc, PhD; Bueno CE,  Nowakowski A, Cunha RS. , Influence of Irrigating Solution on Postoperative Pain Following Single-Visit EndodonticTreatment: Randomized Clinical Trial . J Can Dent Assoc 2012;78c84.







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Derek Richards

Derek Richards is a specialist in dental public health, Director of the Centre for Evidence-Based Dentistry and Specialist Advisor to the Scottish Dental Clinical Effectiveness Programme (SDCEP) Development Team. A former editor of the Evidence-Based Dentistry Journal and chief blogger for the Dental Elf website until December 2023. Derek has been involved with a wide range of evidence-based initiatives both nationally and internationally since 1994. Derek retired from the NHS in 2019 remaining as a part-time senior lecturer at Dundee Dental School until the end of 2023.

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