Clinical Accuracy of Electronic Apex Locator in Measuring Working Length during Root Canal Treatment

Abstract

Obtaining a correct working length is critical to success of endodontic therapy. The procedure for establishment of working length should be performed using techniques that have been proven to give valuable and accurate results and methods that are practical and efficacious. The development of the electronic apex locator has helped to assess the working length more accurate and predictable. So the objective of this in vivo-ex vivo study was to evaluate the clinical accuracy of electronic apex locator in measuring the working length of the root canal in vivo, and comparing the lengths so measured, to the actual working length, ex vivo and after extraction. Electronic apex locator C-Root-I VI (Foshan COXO Medical Instrument Co. China) was used to measure the working length in 100 root canals (one palatal canal and one buccal canal in fifty maxillary 1st premolar) in vivo before extraction, that were scheduled for orthodontic treatment in twenty-five patients. Teeth were then extracted and apical constrictions were identified by careful preparation of the apical 4 mm of all the roots. Actual working lengths were determined by adjusting an endodontic file in the root canal upto the constriction from the coronal reference point. Electronic working lengths obtained in vivo were then compared for coincidence with the actual lengths thus measured after extraction (ex vivo). The data were statistically analysed by a paired Student 't' test and Pearson correlation-coefficient test. In 14 canals out of 100 electronic working lengths (EWL) truly coincided with actual working length (AWL). Eighty two canals out of 100, EWLs were <0.5 mm short in measurement than AWLs but the difference with AWL was statistically insignificant (p >0.01). Only in 4 canals (4%) EWLs were either >0.5mm short or more than AWL, thereby fail to meet the criteria of acceptable range of coincidence (⩽0.5 mm from the apical constriction). On reliability analysis, all (100%) electronic working length significantly correlate with the actual working length (r=0.971). Within a clinically acceptable range of ⩽0.5 mm, C Root I apex locator device showed a high degree of success (96%) in determination of working length during root canal treatment.