Aim: To establish and compare the relationship between the distance from the file tip to the apical foramen and the numeric meter reading on the display of three different electronic apex locators (EALs).
Methodology: A total of 12 extracted intact, straight, single-rooted human teeth with complete roots were used. The actual root canal length (AL) was determined after access preparation. For the electronic measurements with each EAL, silicon stops were fixed with auto-polymerizing resin to size 15 K-files at AL and 0.5, 1, 2, 3, 4 mm short of AL. The data was analysed by two-way anova and Tukey's honestly significant difference (HSD) test for multiple comparisons amongst EALs. Additionally, one-way anova and Tukey's HSD test were carried out for multiple comparisons amongst the measurements of each EAL.
Results: There was a statistically significant difference amongst all EALs in indicating the position of file tips in relation to the major foramen (P < 0.05). The correlation between the meter reading and the position of the file tip from the apical foramen was statistically significant in the three EALs. There were significant differences amongst the measurements at distances from 0 to 2 mm in Justy III. In Dentaport, significant differences were found from 0 to 1 mm. However, the E-Magic Finder showed significant differences from 0 to 0.5 mm.
Conclusions: Justy III was more capable of displaying the intracanal position of the file tip from the major foramen in mm whilst advancing through the root canal during electronic measurements than the Dentaport and E-Magic Finder Deluxe.