Efficacy of electronic apex locators in comparison with intraoral radiographs in working length determination- a systematic review and meta-analysis

Abstract

Background: Successful endodontic treatment needs accurate determination of working length (WL). Electronic apex locators (EALs) were presented as an alternative to radiographic methods; and since then, they have evolved and gained popularity in the determination of WL. However, there is insufficient evidence on the post-operative pain, adequacy, and accuracy of EALs in determining WL.

Objective: The systematic review and meta-analysis aims to gather evidence regarding the effectiveness of EALs for WL determination when compared to different imaging techniques along with postoperative pain associated with WL determination, the number of radiographs taken during the procedure, the time taken, and the adverse effects.

Methods: For the review, clinical studies with cross-over and parallel-arm randomized controlled trials (RCTs) were searched in seven electronic databases, followed by cross-referencing of the selected studies and related research synthesis. Risk of bias (RoB) assessment was carried out with Cochrane's RoB tool and a random-effects model was used. The meta-analysis was performed with the RevMan software 5.4.1.

Results: Eleven eligible RCTs were incorporated into the review and eight RCTs into the meta-analysis, of which five had high RoB and the remaining six had unclear RoB. Following meta-analysis, no significant difference in postoperative pain was found among the EAL and radiograph groups (SMD 0.00, CI .29 to .28, 354 participants; P value = 0.98). Radiograph group showed better WL accuracy (SMD 0.55, CI .11 to .99, 254 participants; P value = 0.02), while the EAL group had 10% better WL adequacy (RR 1.10, CI 1.03-1.18, 573 participants; P value = 0.006).

Conclusion: We found very low-certainty evidence to support the efficacy of different types of EAL compared to radiography for the outcomes tested. We were unable to reach any conclusions about the superiority of any type of EAL. Well-planned RCTs need to be conducted by standardizing the outcomes and outcome measurement methods.

Keywords: Apex locator; Endodontic; Radiographs; Root canal treatment; Working lengt.

Fig. 1

Flow diagram showing the literature selection process

Fig. 2

a Risk-of-bias summary. Review authors' judgements about each risk of bias item for each included study. Green colour indicates ‘low risk of bias’, yellow indicates ‘unclear risk of bias’ and red colour indicates ‘high risk of biases. b Review authors' judgements about each risk of bias item presented as percentages across all included studies. Green indicates ‘low risk of bias’, yellow indicates ‘unclear risk of bias’ and red indicates ‘high risk of biases

Fig. 3

a Forest plot showing post-operative pain (Electronic Apex Locator Vs Radiographs). b Forest plot showing adequacy in WL determination (Dichotomous data). c Forest plot showing the accuracy of WL determination (Continuous data)