Precision of endodontic working length measurements: a pilot investigation comparing cone-beam computed tomography scanning with standard measurement techniques.

Introduction: The objective of this pilot investigation was to evaluate the utility and precision of already existing limited cone-beam computed tomography (CBCT) scans in measuring the endodontic working length, and to compare it with standard clinical procedures.

Methods: Three patients referred to the department received limited CBCT scans for diagnostics and preoperative treatment planning of cystic jawbone pathologies. Part of the therapy consisted of root canal treatments before surgical enucleation of the lesion. For the determination of the working length, the root canal length was measured with an electronic apex locator (EAL) by the endodontist. This measurement was compared with the root canal length as measured on the respective CBCT scans by an examiner not involved in the endodontic treatment. The interrater agreement between the two examiners was analyzed to determine the feasibility of this technique.

Results: In the three included patients, 9 teeth with a total of 10 root canals were treated. For these canals, a strong correlation was found between the endodontic working length as measured in the CBCT images and the EAL measurements (Pearson correlation coefficient ranging from 0.904 to 0.968).

Conclusions: Based on the present findings, an already existing CBCT scan of teeth to be endodontically treated can be useful to determine the endodontic working length in combination with clinical measurements such as the EAL. Future prospective studies should evaluate if and when intraoral radiography for measuring the length of root canals can be avoided when CBCT images are available.