Accuracy of two different apex locators for working length determination during root canal retreatment of mandibular molars using two different retreatment files: An in vitro study

Abstract

Aim: The aim of this study was to determine the accuracy of two different apex locators for measurement of working length during root canal retreatment of mandibular molars with two different file systems in an ex vivo study. Materials and Methods: Sample consisting of sixty extracted mandibular first molars was selected. Tooth length was measured with a file. Biomechanical preparation of the roots was done with Protaper files 1mm short of the tooth length. Canals were coated using AH Plus sealer and were obturated with gutta percha. Obturating material was removed after one week with two files i.e Protaper and Mtwo retreatment files. Tooth length was remeasured and recorded as the retreatment tooth length (RTL). Then electronic measurements were taken with Root ZX and Apex ID apex locator as suggested by the instrument display. These lengths were compared with RTL at 0.5 and 1 mm short of this distance. Results: For both canals, no significant difference was found between RTL and EAL measurements with Root ZX apex locator and protaper retreatment files. There was a significant difference between Apex ID apex locator with M2 retreatment files readings. Conclusion: Root ZX apex locator was more accurate as compared to Apex ID apex locator in determining the working length in teeth after removing the root canal obturating material using two different files.