… For successful endodontic outcome, accurate working length has to be determined. Even with improved systems of working length (WL) measurement, different readings may be recorded in different electrolytes present in the canal. Methodology: Total 90 patients were selected for this prospective in vivo study resented at

For successful endodontic outcome, accurate working length has to be determined.Even with improved systems of working length (WL) measurement, different readings may berecorded in different electrolytes present in the canal. Methodology: Total 90 patients wereselected for this prospective in vivo study resented at Department of Operative Dentistry, LiaquatUniversity of Medical & Health Sciences, Jamshoro, during 6 months i.e. from 1st Sep 2014 to28th Feb 2015, with single rooted permanent mandibular first premolars with matured apices.After extirpated pulp tissue a file was inserted in the canal and WL was obtained by radiographas well as by electronic apex locator (EAL). The measurements determined by both methodswere compared by applying paired sample t-test. SPSS 18 was used for data analysis. Results:Among 90 subjects 37 were males. Mean±SD WL obtained radiographically was 19.8±1.03-mwhereas mean±SD WL obtained electronically was 18.9±1.05 mm. Mean difference betweenmeasurements of both methods was 0.87-mm, which was statistically significant (P <0.05).Conclusion: The electronic apex locator was better than the radiograph in determining workinglength of root canal at statistically significant level.