Successful root canal treatment depends on thorough cleaning & shaping and 3- dimensional fluid impervious obturation of tooth within the confines of canals. To achieve this objective the apical constriction must be detected accurately during canal preparation and precise control over working length during the procedure must be maintained. There are many methods of working length determination including electronic method. Introduction of apex locators have definitely served as an effective adjuvant to radiographs. This article highlights the details of electronic apex locators which are available till now including development, generations, historical background, mode of action, classification, problems associated with the use and clinical acceptance.
Keywords: Apex locators, Apical constriction, Endodontics, Resistance, Working length
