In Vitro Accuracy of the E-PEX Electronic Apex Locator Compared to the Root ZX II

Abstract

Introduction: One of the challenges of non-surgical root canal treatment (NSRCT) is determining the working length of the canal which indicates the exact end point of root canal preparation and obturation. The development of the Electronic Apex Locator (EAL) has helped the clinician to determine the location of the apical foramen, and hence the working length, when performing NSRCT. Objective: The objective of this in vitro study was to determine the accuracy of a new EAL, the E-PEX (Changzhou Eighteeth Medical Technology Co., China), and compare it to a commonly used EAL, the Root ZX II (J. Morita Corp, Kyoto, Japan), for determining the location of the apical foramen. Materials and Methods: Twenty extracted single rooted teeth were used in this study. The crowns were removed and the distance from a coronal reference point to the apical foramen was measured utilizing a k-file and direct visualization under magnification. Teeth were then mounted in alginate and measurements for the apical foramen were made using the Root ZX II and the E-PEX. The difference between the actual canal length and the electronic length was then calculated and compared. Results: The mean true difference was -0.20, and -0.19 for the E-PEX and Root ZX II respectively. The mean absolute difference was 0.28, and 0.26 for the E-PEX and Root ZX II respectively. Paired t-tests done separately for true differences (p = 0.45) and absolute differences (p = 0.21) showed no significant difference among EALs. The percentage of measurements falling within 0.5 mm of the actual canal lengths for each EAL were 95% and 90% for the E-PEX and Root ZX II respectively. McNemar’s test was used to compare between the two test methods for the percentage within 0.5 mm and revealed no significant difference (p = 0.32). Conclusion: The Root ZX II had an average measurement that was slightly closer to the actual length of the canal when compared to the E-PEX, while the E-PEX had a higher percentage of measurement within 0.5 mm of the apical foramen. However, these differences were not statistically significant.