A comparative evaluation of working length with digital radiography and third generation apex locator (ProPex) in the presence of various intracanal irrigants: An in vivo/ex vivo study

BACKGROUND Accurate working length determination is a pre-requisite for a successful endodontic treatment. Even with improved systems of working length measurement, different readings may be recorded in different electrolytes present in the canal. The purpose of this in vivo/ex vivo comparative study was to determine the accuracy in measuring the working length of root canal using Direct Digital Radiographic Method (Radiovisiography or RVG) and ProPex electronic apex locator in the presence of three different irrigating solutions: 0.9% normal saline, 2% chlorhexidine, 3% NaOCl solutions. MATERIALS AND METHODS Forty single-rooted human teeth scheduled for extraction with mature apices were selected for this study. Measurements were performed by using RVG and ProPex in the presence of irrigating solutions. After extraction of the teeth, light microscope was used to confirm visually the relationship of the tip of the endodontic file to the apical foramen, and actual lengths were determined by reducing 0.5 mm from this length. The statistical analysis was performed by one-way ANOVA test and Tukey-HSD post hoc procedure. P < 0.05 was considered as significant. RESULTS No significant difference was found between overall mean electronic working length and digital radiographic length; however, prediction error (P < 0.05) was significant with respect to different irrigants. Among the irrigating solutions, chlorhexidine gluconate had the smallest distance to the actual lengths, whereas NaOCl had the greatest. CONCLUSION Electronic apex locator ProPex yielded best result in the presence of chlorhexidine, whereas the largest error was demonstrated with NaOCl indicating that higher electroconductive irrigating solutions affect the precision of multi-frequency apex locators.