In vitro assessment of the accuracy of three electronic apex locators

Aim of this in vitro study was to compare accuracy of three electronic apex locators (EALs) (ES-02, ES-03 and ProPex) in root canals of extracted human teeth utilizing two meter readings and diff erent conditions of root canals (RC). RC lengths of 46 single-rooted teeth were visually determined using a K-fi le # 15. Teeth and labial connector were then embedded in alginate. Two sets of measurements were performed for each device - root canal condition combination (dry root canal, 2.5% NaOCl, 17% EDTA, RC prep, Glyde) according to readings “-0.5” and “0.0”. The diff erences were evaluated using descriptive and nonparametric statistics. The mean diff erence between real and measured values at meter reading “0.0” was 0.10 mm with ProPex, 0.31 mm with ES-02 and 0.71 mm with ES-03. At meter reading “-0.5“ that diff erence was 0.28 mm with ProPex, 0.41 mm with ES-02 and 0.87 mm with ES-03. In vitro testing showed ProPex to be the most accurate EAL in most of combinations, followed by ES-02, and ES-03 (p<0.05). Most accurate measurements were performed in canal conditions as follows: dry canals, Glyde, Rc-Prep, NaOCl and EDTA solutions (p<0.05). ProPex was the most accurate at meter reading “0.0”. At reading “-0.5” ES-02 and ProPex were equal, whereas ES-03 was the least accurate. All tested EALs should be used with meter reading “0.0” as a reference because it is more accurate than using the meter reading “-0.5” (p<0.001).