No evidence favouring one irrigant versus another in root canal treatments

The Cochrane Oral Health Group's Trials Register, CENTRAL, Medline, Embase, and LILACS databases were searched with no restrictions.

Randomised controlled trials (RCTs) involving single or multi-rooted permanent teeth requiring root canal treatment (RoCT) which compared irrigants against each other or against inactive irrigant or placebo were included. Combinations of irrigants were allowed and if used in conjunction with EDTA (ethylenediaminetetra-acetic acid) or similar chelating agents.

Two review authors independently assessed risk of bias of included trials and extracted data.

Eleven trials (851 participants, 879 teeth) were included. Six trials were assessed at high risk of bias, three unclear and two low. Four compared sodium hypochlorite versus chlorhexidine, the other trials compared different interventions and only two of these trials included useable data on the primary outcomes of swelling and pain. Meta-analysis of sodium hypochlorite versus chlorhexidine indicated no strong evidence of a difference in the existence of bacterial growth between the interventions (risk ratio 0.73; 95% confidence interval 0.34 to 1.56; P = 0.41). None of the included trials reported any data on adverse effects nor radiological changes in periapical radiolucency.

Although root canal irrigants such as sodium hypochlorite and chlorhexidine appear to be effective at reducing bacterial cultures when compared to saline, most of the studies included in this review failed to adequately report these clinically important and potentially patient-relevant outcomes. There is currently insufficient reliable evidence showing the superiority of any one individual irrigant. The strength and reliability of the supporting evidence was variable, and clinicians should be aware that changes in bacterial counts or pain in the early postoperative period may not be accurate indicators of long-term success. Future trials should report both clinician-relevant and patient-preferred outcomes at clearly defined perioperative, as well as long-term, time points.