Accuracy of an electronic apex locator: a clinical evaluation in primary molars with and without resorption

The aim of this study was to evaluate the accuracy of electronic apex locator (Root ZX) in primary teeth with and without apical root resorption in vivo.

The electronic working length was determined in 28 primary teeth (A total of 46 primary molar root canals with 24 roots without resorption and 22 roots with resorption) from twenty-eight healthy children using Root ZX. The teeth were then extracted. The actual length of each root was measured placing a K-File until the tip was visible at the apical foramen or the apical resorption level and approved with digital microscopic evaluation under 20x magnification and then withdrawn 1 mm. The distances from the file tip to the base of the rubber stop were measured and compared with the measurement obtained from apex locator. The data were evaluated with t test using standard statistical software (SPSS 13.0). The critical value of statistical significance was 5%.

For root canals without resorption, the accuracy of Root ZX was 79.16% and 95.82% within +/- 0.5 and +/- 1 mm, respectively. For root canals with resorption, the accuracy of Root ZX was 63.63% and 86.35% within +/- 0.5 and +/- 1 mm, respectively. No statistically significant differences were detect between the electronically determined lengths and the actual lengths regardless of whether or not resorption.

Using a Root ZX Electronic Apex Locator in primary teeth with or without resorption is recommended for the determination of working length.