Accuracy of the electronic apex locator, tactile, and radiographic methods in working length determination

Background: Determination of working length (WL) is necessary for the successful outcome of root canal treatment (RCT). Common methods in WL determination include tactile, radiographic, and electronic apex locators (EAL).

Aim: The aim of this study was to compare three methods of WL determination to the actual visualization of the apical constriction (AC).

Materials and methods: Consecutive patients with indications for extraction of single-rooted single canal teeth at the University of Ghana Dental School clinic were randomly assigned to three groups. In-vivo root canal WL was determined by tactile sensation, digital radiography, and a 5^th generation EAL (Sendoline S5). Files were cemented in the canals after the in-vivo measurements. The apical 4-5 mm of the roots was trimmed to expose the inserted files and the AC. Actual WL, as determined by visualization of the AC, was done using a digital microscope. Different WLs were then compared for the various groups, and the mean actual canal lengths were reported.

Results: EAL accurately predicted the AC in 31 (96.9%) teeth, while the digital radiographic and tactile sensation methods accurately predicted the constriction in 19 (59.4%) and 8 (25%) teeth, respectively, in the study population. The mean working canal lengths for single-rooted teeth showed no observable difference among sexes, age categories, and side of the jaw.

Conclusion: The EAL provided more reliable and accurate WL measurements for single-rooted teeth among Ghanaians, compared to digital radiography and tactile methods.