Single versus multiple visits for endodontic treatment of permanent teeth

Background: Root canal treatment (RoCT), or endodontic treatment, is a common procedure in dentistry. The main indications for RoCT are irreversible pulpitis and necrosis of the dental pulp caused by carious processes, coronal crack or fracture, or dental trauma. Successful RoCT is characterised by an absence of symptoms (i.e. pain) and clinical signs (i.e. swelling and sinus tract) in teeth without radiographic evidence of periodontal involvement (i.e. normal periodontal ligament). The success of RoCT depends on a number of variables related to the preoperative condition of the tooth, as well as the endodontic procedures. RoCT can be carried out with a single-visit approach, which involves root canal system obturation (filling and sealing) directly after instrumentation and irrigation, or with a multiple-visits approach, in which the treatment is completed in two or more sessions and obturation is performed in the last session. This review updates the previous versions published in 2007 and 2016. Objectives: To evaluate the benefits and harms of completion of root canal treatment (RoCT) in a single visit compared to RoCT over two or more visits, with or without medication, in people aged over 10 years. Search methods: We used standard, extensive Cochrane search methods. The latest search date was 25 April 2022. Selection criteria: We included randomised controlled trials and quasi-randomised controlled trials in people needing RoCT comparing completion of RoCT in a single visit compared to RoCT over two or more visits.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were 1. tooth extraction and 2. radiological failure after at least one year (i.e. periapical radiolucency). Our secondary outcomes were 3. postoperative and postobturation pain; 4. swelling or flare-up; 5. analgesic use and 6. presence of sinus track or fistula after at least one month. We used GRADE to assess certainty of evidence for each outcome. We excluded five studies that were included in the previous version of the review because they did not meet the current standard of care (i.e. rubber dam isolation and irrigation with sodium hypochlorite). Main results: We included 47 studies with 5805 participants and 5693 teeth analysed. We judged 10 studies at low risk of bias, 17 at high risk of bias and 20 at unclear risk of bias. Only two studies reported data on tooth extraction. We found no evidence of a difference between treatment in one visit or treatment over multiple visits, but we had very low certainty about the findings (risk ratio (RR) 0.46, 95% confidence interval (CI) 0.09 to 2.50; I2 = 0%; 2 studies, 402 teeth). We found no evidence of a difference between single-visit and multiple-visit treatment in terms of radiological failure (RR 0.93, 95% CI 0.81 to 1.07; I2 = 0%; 13 studies, 1505 teeth; moderate-certainty evidence). We found evidence of a higher proportion of participants reporting pain within one week in single-visit groups compared to multiple visit groups (RR 1.55, 95% CI 1.14 to 2.09; I2 = 18%; 5 studies, 638 teeth; moderate-certainty evidence).  We found no evidence of a difference in the proportion of participants reporting pain until 72 hours postobturation (RR 0.97, 95% CI 0.81 to 1.16; I2 = 70%; 12 studies, 1329 teeth; low-certainty evidence), pain intensity until 72 hours postobturation (mean difference (MD) 0.26, 95% CI -4.76 to 5.29; I2 = 98%; 12 studies, 1258 teeth; low-certainty evidence) or pain at one week postobturation (RR 1.05, 95% CI 0.67 to 1.67; I2 = 61%; 9 studies, 1139 teeth; very low-certainty evidence). We found no evidence of a difference in swelling or flare-up incidence (RR 0.56 95% CI 0.16 to 1.92; I2 = 0%; 6 studies; 605 teeth; very low-certainty evidence), analgesic use (RR 1.25 95% CI 0.75 to 2.09; I2 = 36%; 6 studies, 540 teeth; very low-certainty evidence) or sinus tract or fistula presence (RR 1.00, 95% CI 0.24 to 4.28; I2 = 0%; 5 studies, 650 teeth; very low-certainty evidence). Subgroup analysis found no differences between single-visit and multiple-visit RoCT for considered outcomes other than proportion of participants reporting post-treatment pain within one week, which was higher in the single-visit groups for vital teeth (RR 2.16, 95% CI 1.39 to 3.36; I2 = 0%; 2 studies, 316 teeth), and when instrumentation was mechanical (RR 1.80, 95% CI 1.10 to 2.92; I2 = 56%; 2 studies, 278 teeth). Authors' conclusions: As in the previous two versions of the review, there is currently no evidence to suggest that one treatment regimen (single-visit or multiple-visit RoCT) is more effective than the other. Neither regimen can prevent pain and other complications in the 12-month postoperative period. There was moderate-certainty evidence of higher proportion of participants reporting pain within one week in single-visit groups compared to multiple-visit groups. In contrast to the results of the last version of the review, there was no difference in analgesic use.