Postoperative pain following irrigation

Over the past few years, endodontic journals have witnessed a significant surge in the number of clinical trial submissions that evaluate postoperative pain as a single primary outcome following the use of different root canal irrigants, irrigation techniques or regimens (Demenech et al., 2021; Gondim Jr et al., 2010; Mostafa et al., 2020; Ramamoorthi et al., 2015; Sahai et al., 2023; Topçuoğlu et al., 2018). There are obvious reasons for this, as it is well recognized that pain is important and is a core issue related to Endodontic treatment (El Karim et al., 2024) as well as being of considerable relevance as a patient-centred outcome measure (Doğramacı & Rossi-Fedele, 2023). In addition, conducting clinical trials with short-term pain outcomes can be relatively simple, less costly with minimal attrition and loss of patients due to long-term follow-up. However, the evaluation of postoperative pain after the use of different root canal irrigants or irrigation techniques is a short-term or surrogate outcome that does not necessarily correlate with the resolution or prevention of apical periodontitis or tooth retention (Duncan et al., 2023). Indeed, an assessment of postoperative pain may only be valuable as part of a larger study evaluating the long-term outcome of irrigation protocols on apical disease or the survival of root-filled teeth. The abundance of short-term pain studies, with no extended follow-up and often conflicting results, unfortunately, does not offer substantial insights into the relative efficacy or effectiveness of endodontic treatment protocols (Rossi-Fedele & Rödig, 2023). The prevalence of postoperative pain after root canal treatment has been reported to range between 3% and 58% (Sathorn et al., 2008), with a classic pattern of pain peaking at 1-day post-treatment and continuing to drop too low levels after 7 days (Pak & White, 2011). The majority of the studies evaluating postoperative pain using a range of different irrigants or irrigating techniques demonstrate mild pain which lasts for a period of maximum 24–48 h (Ballal et al., 2019; Demenech et al., 2021; Gondim Jr et al., 2010; Liapis et al., 2021; Ramamoorthi et al., 2015; Topçuoğlu et al., 2018). This transient postoperative pain can generally be managed with over-the-counter analgesic medication and may have little impact on the patients' quality of life and satisfaction with treatment in the long term. Certainly, it is questionable whether an evaluation of postoperative pain after irrigation, without long-term follow-up, provides important clinical information for the success of root canal treatment.

In conclusion, there is questionable relevance of short-term pain as the primary outcome measure in the comparison of irrigants or irrigation protocols in endodontics. If comparative clinical trials are to be performed in this area, they should ideally be accompanied by longer-term follow-up or the aforementioned variables should be meticulously controlled, in order to limit the effect of confounding factors. In addition, more objective surrogate outcomes should be considered, such as the levels of inflammatory markers in the periapical fluid (Ballal et al., 2019; Shimauchi et al., 1996). So, although the International Endodontic Journal continues to welcome manuscripts investigating irrigants and irrigation protocols in Endodontics, the value of short-term postoperative pain studies in isolation needs to be considered carefully.