A comparative evaluation of root canal length measurement techniques in primary teeth.

Purpose: The purpose of this 3-staged, in vivo, crossover study was to comparatively evaluate the accuracy of radiograph-based and apex locator-based measurements of working length in primary molars with physiological root resorption.

Methods: Endodontic access cavity preparations were performed on 13 primary molars in 10 cooperative pediatric dental outpatients who met the selection criteria. Calibrated investigators estimated the root canal length in a total of 30 canals in these 13 primary molars using both apex locators and radiographs.