RESUMEN
INTRODUCTION: iPex is a fourth-generation apex locator (EAL) that has not yet been tested in vivo. The purpose of this study was to compare the accuracy of the Root ZX (J Morita Corp, Tokyo, Japan) and iPex (NSK, Tochigi, Japan) EALs. METHODS: The working length (WL) was determined electronically for 40 root canals of human teeth with a K-file and one of the two EALs. The files were fixed at the WL, and the teeth were extracted. The apical 4 mm of each canal was trimmed to expose the file tip. The samples were observed under a scanning electron microscope, and the distance from the file tip to the point 0.5 mm coronal to the major foramen (the actual WL) was measured. The data were analyzed using the Mann-Whitney U test, and significance was set at P < .05. RESULTS: No statistically significant differences were found between the Root ZX and iPex devices. The mean distance from the actual WL to the file tip was 0.146 ± 0.43 mm for the Root ZX and 0.128 ± 0.49 mm for the iPex. In determining the actual WL, the Root ZX was accurate 72% of the time to ± 0.5 mm and 100% of the time to ± 1 mm, whereas the iPex was accurate 57.8% of the time to ± 0.5 mm and 100% of the time to ± 1 mm. CONCLUSIONS: Under the in vivo clinical conditions of this study, no statistically significant differences were observed between the Root ZX and iPex EALs.