evaluation of the accuracy of two apex locators in endodontic treatment and retreatments: an ex vivo study

Introduction: working length determination is important in successful endodontic treatment and retreatment.this study evaluated the accuracy of two electronic apex locators root zx and raypex®6 (eals) in determining the electronic working length (ewl) of the root canals in endodontic treatment and retreatment.materials and methods: access cavities were prepared on forty extracted, singlerooted human teeth and the actual working length (awl) of the canals was determined. in the first phase of the study, primary ewl of uninstrumented teeth was measured and compared between two eals. in phase ii, all of the teeth were preflared and divided into the control(n=10) and the retreatment groups (n=30). canals in the retreatment group were obturated by the lateral condensation technique using gutta percha and sealer. after 15 days, guttapercha was removed, and then the secondary ewl was recorded and compared between the two devices, in treatment and retreatment groups. data were analysed by paired ttest and ttest.results: significant differences were found between both eals in treatment and retreatment phases of the study (p<0.001).both eals showed increased accuracy in retreatment group (p<0.001). however, no statistically significant differences were found between the control and retreatment groups in the second phase of the study for root zx (p = 0.929), and raypex®6 (p=0.937).conclusion: accuracy of the two eals was similar and acceptable. ewls determined by root zx were closer to the awl. the ewl determination after preflaring improved the accuracy of eals and root canal obturation remnant materials did not have any clear effect on the accuracy of these eals.