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

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).

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

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.

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.

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