Post endodontic pain: Is it affected by irrigation technique?


Post endodontic pain is an adverse outcome from root canal treatment. It has been linked to both the type of irrigant used to clean canals and the irrigation technique.  Some studies have suggested that ultrasonic irrigation can reduce post endodontic pain.

The aim of this review was to assess whether ultrasonic irrigation results in less postoperative pain following root canal treatment than conventional irrigations


A protocol was registered on PROSPERO and searches were conducted in the Medline/PubMed, Scopus, Web of Science, Embase, Cochrane Library, and OpenGrey databases. This was supplemented by searches of the journals, Journal of Endodontics, International Endodontic Journal, Australian Endodontic Journal, Iranian Endodontic Journal, European Endodontic Journal, Clinical Oral Investigations, and Journal of Dentistry. Randomised controlled trials (RCTs) that compared conventional(syringe) and ultrasonic irrigation and assessed post-operative pain were considered. Two reviewers independently selected studies extracted data and assessed risk of bias using the Cochrane domains-based tool. Meta-analysis of post-operative pain at different time intervals was conducted and the overall quality of evidence assessed using GRADE.


  • 6 RCTs involving a total of 554 patients were included.
  • 2 studies were conducted in Turkey, 2 in India and 2 in China.
  • 5 studies used a visual analogue scale (VAS) to evaluate pain.
  • In general, the highest levels of pain were recorded in the first 24 hours.
  • 3 studies had a low risk of bias, 1 a high risk and 2 an unclear risk.
  • 4 RCTs contributed to the meta-analyses which showed reduced pain with ultrasonic irrigation up to 48hrs but not a 48 hours or 7 days (see table below).
Post-operative pain No. of Studies Mean Difference (95%CI)
6 hrs 2 -1.40 (-2.38 to -0.42)
24 hrs 4 -0.83 (-1.68 to -0.02)
48 hrs 4 -0.50 (-1.22 to -0.23)
72 hrs 2 -0.39 (-2.89 to 2.10)
7 days 2  0.00 (-0.09 to 0.09)
  • The authors rated the certainty of the evidence at 24hrs, 48hrs and 7 days as moderate and low for 6hrs and 72 hrs.


The authors concluded: –

..the evidence suggests that ultrasonic irrigation of root canals has a lower incidence of postoperative pain than conventional needle irrigation. Due to the low number of studies and heterogeneity of data, further randomized clinical trials are recommended to provide better understanding and support of the findings obtained in this review.


A wide range of sources was searched by the authors for this review with 6 RCTs meeting the inclusion criteria. Three of the 6 RCTs were considered to be at low risk of bias with 4 RCTs contributing to the meta-analyses. All of the studies used sodium hypochlorite (NaOCl) as the irrigant solution although this ranged from 2.5% to 5% and a previous study (Dental Elf – 5th Feb 2020) has suggested that a higher concentration of NaOCl may be associated with more post-operative pain. This review suggests less pain with ultrasonic irrigation for the first 48 hours but no difference at 72 hours. However, pain is influenced by a range of variables, and it would be helpful to have more information on pre-operative pain levels and use of analgesics and rescue medication and patient reported outcomes. Future studies should follow the new PRIRATE guidelines.


Primary Paper

Chalub LO, Nunes GP, Ferrisse TM, Strazzi-Sahyon HB, Dos Santos PH, Gomes-Filho JE, Cintra LTA, Sivieri-Araujo G. Postoperative pain in root canal treatment with ultrasonic versus conventional irrigation: a systematic review and meta-analysis of randomized controlled trials. Clin Oral Investig. 2022 Jan 28. doi: 10.1007/s00784-022-04386-0. Epub ahead of print. PMID: 35091819.

Review protocol on PROSPERO

Other references

Dental Elf – 5th Nov 2021

Post-operative endodontic symptoms: Are they improved by prophylactic antibiotics?

Dental Elf – 21st Aug 2020

Root canal disinfection: Sodium hypochlorite or chlorhexidine?

Dental Elf – 5th Feb 2020

Post-endodontic pain: Is it influenced by concentration of sodium hypochlorite irrigation?



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