Accuracy of electronic apex locator (EAL) and radiographic film (RF) and digital radiography (DR) to determine working length

Working length determination is one of the most important steps during root canal therapy. Many devices and various methods have been introduced for that purpose amongst them is electronic apex locators and various radiographic systems. This study was carried out to assess the accuracy of electronic apex locator (EAL) and compare radiographic film (RF) and digital radiography (DR) in order to determine working length.

In this study, 36 teeth from 3 cadavers’ jaws which had 38 root canals were used. At first, in each canal a k-type file was inserted into the canal until the Apex signal was emitted by EAL. Afterwards, the file was fixed into the pulp chamber, by cyanoacrylate glue. X-ray images were obtained by RF and DR methods. In order to compare the results of the radiographic methods and EAL as well as determination of apical opening (AO), stereomicroscopic observation was used as gold standard following selective grinding.

Results showed that the accuracy of EAL (in ±0.5 mm) was 100%. Agreement observation between (DR and RF), (DR and EAL) and (RF and EAL) were 73.6%, 55.2% and 52.6% respectively. The spearman correlation coefficient showed significant difference between (DR, RF), (DR, EAL) and (RF, EAL) (P<0.05).

This study showed that EAL has excellent accuracy (100%) and DR is a valuable method which can be substituted with RF.