The accuracy of Root ZX electronic apex locator

The aim of this review was to evaluate studies assessing the accuracy of Root ZX when used for working length determination in permanent teeth and to identify factors affecting the device′s precision. An electronic search for articles published in English language since 1994 was conducted on the Medline via Ovid interface. All issues of the International Endodontic Journal, Journal of Endodontics and Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology since 1994 were manually searched. The reference lists of review articles were cross-referenced to identify any potential publications. A total of 76 publications fulfilled the inclusion criteria. The studies varied in their methodologies, and most of them did not adhere to the manufacturer′s recommendations while operating the device. The Root ZX failed to consistently detect the apical constriction or the apical foramen. Nonetheless, it mostly allowed file tip placement in the area bounded by these two landmarks, especially when the 0.5 mark of its digital meter was adopted. Tooth-related factors potentially influencing the precision of Root ZX included pre-operative pulp status, tooth type, position of the apical foramen, canal obliteration, and the size of apical diameter. Operative factors including coronal pre-flaring, presence or absence of irrigants, file size, file alloy, and mode of file operation could also influence the performance of Root ZX. In conclusion, adopting the 0.5 mark of the digital meter of the Root ZX reduces chances of violating the apical foramen. Further, factors influencing the precision of Root ZX must be considered while operating it.