Does single-visit root canal treatment of permanent teeth provide more benefit than a multiple-visit approach?

Cochrane Oral Health's Trials Register, Cochrane Central Register of Controlled Trials in the Cochrane Library, MEDLINE Ovid, Embase Ovid.

Randomised controlled trials and quasi-randomised controlled trials were included.

Participants aged ≥ 10 with a permanent tooth possessing a completely formed apex and without resorption; Intervention: Root canal treatment (RoCT) carried out in a single visit; Comparison: RoCT carried out over multiple visits; Outcome: Primary outcome was treatment success (retention of tooth or radiographic evidence of healing), with secondary outcomes investigating post-operative symptoms (pain, swelling, sinus tract formation).

Standard Cochrane methods to assess internal validity were used. The Robins 1 tool (for quasi randomised controlled trials) or risk of bias (RoB) 1 tool (for randomised controlled trials) were used to assess RoB whereby a judgement was assigned as 'low', 'high' or 'unclear'. GRADE (GRADEpro GDT software) was used to assess certainty of evidence for each outcome. The certainty of evidence was defined as high, moderate, low or very low, having no downgrade, downgrade of one level, downgrade of two levels and downgrade of three or more levels, respectively. Of the various subgroups investigated to determine their relevance, only pretreatment conditions (vital teeth versus necrotic teeth) and endodontic technique (manual versus mechanical instrumentation) were available for subgroup analysis. The Cochrane's test for heterogeneity and I² test were used to assess the variation in treatment effects. A random-effects model was used to combine risk ratio (RR) for dichotomous data and mean difference (MD) for continuous data. Sensitivity analysis was performed for each outcome, excluding studies at overall high or unclear RoB.

Forty-seven studies were included in the meta-analysis and internal validity assessment, with 5693 teeth analysed. Ten studies were found to have a low RoB, 17 with a high RoB and 20 with an unclear RoB. No evidence was identified suggesting a difference between treatment carried out in a single visit compared to a multiple visits approach for the primary outcome measure, but there was very low certainty about the findings (RR 0.46, 95% confidence interval (CI) 0.09 to 2.50; I 2 = 0%; 2 studies, 402 teeth). No evidence was identified suggesting a difference between treatment carried out in a single visit compared to multiple visits with regards to radiological failure (RR 0.93, 95% CI: 0.81 to 1.07; I 2 = 0%; 13 studies, 1505 teeth; moderate-certainty evidence), participants reporting pain up to 72 h post obturation (RR 0.97, 95% CI: 0.81 to 1.16; I 2 = 70%; 12 studies, 1329 teeth; low-certainty evidence), pain for 72 h post obturation (MD 0.26, 95% CI: -4.76 to 5.29; I 2 = 98%; 12 studies, 1258 teeth; low-certainty evidence) or pain at 1 week post obturation (RR 1.05, 95% CI: 0.67 to 1.67; I2 = 61%; 9 studies, 1139 teeth; very low-certainty evidence). Similarly, no evidence was identified to prove that there was a difference between treatment carried out in a single visit compared to multiple visits with regards to swelling or flare-up (RR 0.56 95% CI: 0.16-1.92; I 2 = 0%; 6 studies; 605 teeth; very low-certainty evidence), analgesic use (RR 1.25 95% CI: 0.75-2.09; I 2 = 36%; 6 studies, 540 teeth; very low-certainty evidence) and sinus tract or fistula presence (RR 1.00, 95% CI: 0.24-4.28; I 2 = 0%; 5 studies, 650 teeth; very low-certainty evidence). Interestingly, however, there was evidence to show that more participants reported pain after 1 week following RoCT completed in a single visit, compared to those in multiple visit groups (RR 1.55, 95% CI: 1.14-2.09; I 2 = 18%; 5 studies, 638 teeth; moderate-certainty evidence). Subgroup analysis showed there was an increase in post-treatment pain after 1 week for RoCT carried out in a single visit on vital teeth (RR 2.16, 95% CI: 1.39-3.36; I 2 = 0%; 2 studies, 316 teeth), and with the use of mechanical instrumentation (RR 1.80, 95% CI: 1.10-2.92; I 2 = 56%; 2 studies, 278 teeth).

The current evidence shows that RoCT carried out in a single visit is no more effective than RoCT carried out over multiple visits; after 12 months, there is no difference in pain or complications with either approach. However, single visit RoCT has been shown to have increased post-operative pain after 1 week compared to RoCT completed over multiple visits.