RESUMEN
To evaluate the use of electronic apex locator to measure the root canal length in primary teeth, comparing this measure with the measurements obtained by conventional radiography and by the direct measurement of the root canal lenght.Material and Methods:The sample consisted of nine multi-rooted primary teeth, totaling 32 root canals. Endodontic access was performed with a spherical diamond tip, then the pulp was extirpated and the canal irrigated with 0.9% saline. An endodontic file was used to measure the root canal length by electronic apex locator, using the Novapex ® according to the manufacturer's instructions, and by direct method. An endodontic ruler was used to determine fileÆs length. Conventional radiographic was also performed. Statistical analysis was performed by analysis of variance (ANOVA). The level of significance was 95%.Results:The average of the root canal length was 9.98 ± 2.16 to the direct method; 11.52 ± 1.87 to conventional radiography; and 10.91 ± 1.92 to the electronic apex locator. The results of this study showed a high correlation between the values given by the different methods, regardless of the presence or absence of physiological root resorption. There were not statistically significant differences amongst the methods studied (p> 0.05).Conclusion:Electronic apex locator was an accurate method measure the root canal length in primary teeth, and its use is indicated in endodontic treatment of these teeth...