Cochrane on single-visit versus multiple-visit root canals (2022): the same result on the one-year film, more first-week pain after a single visit

What it says#

The review, published by Cochrane Oral Health on December 13, 2022, evaluates the benefits and harms of completing root canal treatment in a single visit compared with treatment over two or more visits, with or without medication between visits, in people aged over 10 years. The authors used standard Cochrane search methods with a latest search date of April 25, 2022, included randomized and quasi-randomized controlled trials, and rated the certainty of the evidence for each outcome with GRADE. They excluded five studies that were in the previous version because those trials did not meet the current standard of care, which the review defines as rubber dam isolation and irrigation with sodium hypochlorite.

Forty-seven studies met the criteria, with 5805 participants and 5693 teeth analyzed. The authors judged 10 studies at low risk of bias, 17 at high risk and 20 at unclear risk. The primary outcomes were tooth extraction and radiological failure after at least one year, meaning a periapical radiolucency; the secondary outcomes were postoperative and postobturation pain, swelling or flare-up, analgesic use, and the presence of a sinus tract or fistula after at least one month.

On the primary outcomes there was no evidence of a difference. Only two studies reported tooth extraction, and the pooled estimate is very uncertain (RR 0.46, 95% CI 0.09 to 2.50; 2 studies, 402 teeth; very low certainty). Radiological failure did not differ between single-visit and multiple-visit treatment (RR 0.93, 95% CI 0.81 to 1.07; 13 studies, 1505 teeth; moderate certainty).

On pain, the one finding with an interval that excludes no difference: a higher proportion of participants reported pain within one week in the single-visit groups (RR 1.55, 95% CI 1.14 to 2.09; 5 studies, 638 teeth; moderate certainty). In subgroup analysis that signal was larger for vital teeth (RR 2.16, 95% CI 1.39 to 3.36; 2 studies, 316 teeth) and when instrumentation was mechanical (RR 1.80, 95% CI 1.10 to 2.92; 2 studies, 278 teeth). There was no evidence of a difference in the proportion reporting pain up to 72 hours after obturation (RR 0.97, 95% CI 0.81 to 1.16; 12 studies, 1329 teeth; low certainty), in pain intensity over the same period (MD 0.26, 95% CI -4.76 to 5.29; 12 studies, 1258 teeth; low certainty) or in pain at one week after obturation (RR 1.05, 95% CI 0.67 to 1.67; 9 studies, 1139 teeth; very low certainty).

The remaining outcomes were all very low certainty and showed no difference: swelling or flare-up (RR 0.56, 95% CI 0.16 to 1.92; 6 studies, 605 teeth), analgesic use (RR 1.25, 95% CI 0.75 to 2.09; 6 studies, 540 teeth) and sinus tract or fistula (RR 1.00, 95% CI 0.24 to 4.28; 5 studies, 650 teeth).

The authors' conclusion is unchanged from the two earlier versions: there is currently no evidence to suggest that one regimen is more effective than the other, and neither regimen can prevent pain and other complications in the 12-month postoperative period. They add that the higher proportion reporting pain within one week after single-visit treatment is moderate-certainty evidence, and that, in contrast to the last version, there was no difference in analgesic use. The plain language summary's key messages are that single-visit and multiple-visit treatments are equally effective whether the pulp is vital or non-vital, and that both approaches are frequently associated with some short-term post-treatment pain.

Who it applies to#

Any permanent tooth in a patient over 10 that needs conventional root canal treatment, vital or necrotic, whether or not a medicament is placed between visits. The trials came from many countries (the plain language summary counts 12 from India) and ranged from 26 to 390 teeth.

It does not reach primary teeth or younger children, and it says nothing about the technique inside the visit; the review's own admission criterion, rubber dam and sodium hypochlorite, is the floor, not a comparison. The extraction outcome, which is the one a patient cares about most, rests on two studies and is very low certainty, so the "equally effective" message stands on the one-year radiograph, not on tooth survival.

What changed#

The review was first published in 2007 and updated in 2016. The 2022 version tightened the entry criteria, dropping five previously included studies whose protocols lacked rubber dam or sodium hypochlorite, and grew to 47 trials. The effectiveness conclusion did not move. What did move is the pain picture: the 2016 version had reported a difference in analgesic use, which the 2022 pooled data no longer show, while the higher proportion of single-visit patients reporting pain within one week is now rated moderate certainty.

Where the source is#

The document is Mergoni and colleagues, Single versus multiple visits for endodontic treatment of permanent teeth, Cochrane Database of Systematic Reviews 2022, issue 12, CD005296.pub4, published by Cochrane Oral Health; the link under the title opens the Cochrane Library page with the abstract and plain language summary. The same text is free in PubMed Central (PMC9747194) and the abstract is on PubMed. When this entry was written the Cochrane Library refused automated access, so the abstract was read from PubMed and the plain language summary from PubMed Central. The full data tables and forest plots are on the Cochrane Library, which may require institutional access in some countries.