Research Article Preoperative Estimation of Endodontic Working Length with Cone-Beam Computed Tomography and Standardized Paralleling Technique in comparison to Its Real Length Bestoon Mohammed Faraj 1,2 1 Conservative Department, College of Dentistry, University of Sulaimani, Iraq 2 Board of Restorative Dentistry, Kurdistan Board of Medical Specialties, Iraq Correspondence should be addressed to Bestoon Mohammed Faraj; bestoon.faraj@univsul.edu.iq Received 6 August 2020; Accepted 21 September 2020; Published 12 October 2020 Academic Editor: Cristiana Corsi Copyright © 2020 Bestoon Mohammed Faraj. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. An accurate estimation of the working canal length is essential for successful root canal treatment. This study is aimed at investigating the diagnostic accuracy of root canal length estimation on cone-beam computed tomography (CBCT) scans and digital paralleling radiographs (PAs), using the real canal length as a gold standard, and at evaluating the influence of canal curvature on this estimation. Sixty extracted human premolar teeth were selected for this study. Root canal length measurement was performed on CBCT scans (NewTom, Giano, Verona, Italy) and digital paralleling radiography (EzRay Air W; Vatech, Korea). The real working length was established by subtracting 0.5 mm from the actual canal length. No significant difference was found between CBCT and digital paralleling radiography. There was a tendency for underestimation of the root canal length measured on the CBCT images in 52 (86.7%) of the examined teeth and overestimation in 5 teeth (8.3%). All the digital radiographs slightly overestimated the real canal length. The analysis revealed a strong correlation between the estimation from moderate to severe curvature for digital radiography and CBCT images. Preoperative working length estimation can be made closest to its real clinical canal length on the standardized paralleling technique, using a long (16-inch) target-receptor distance. 1. Introduction Radiographic working length estimation is an essential component of the overall endodontic diagnosis and treatment planning process. Conventional 2-dimensional (2D) radio- graphs provide a cost-effective, high-resolution image, which continues to be the most popular method of imaging today. However, intraoral radiography has some limitations because of its 2-dimensional nature; information may be difficult to interpret, especially in challenging conditions when the anat- omy and background pattern are complex [1, 2]. Some drawbacks including distortion, magnification, and superimposition may negatively affect the determination of the accurate working length [3]. Furthermore, periapical radiography fails to provide an accurate location of the apex in cases in which an eccentric apical foramen is present [4]. Radiographic imaging is the most commonly used diagnostic tool in endodontic diagnosis and treatment planning. The image distortions constitute a significant inconvenience. Accu- racy of the working length plays a crucial role in determining the success of root canal treatment and could be a predictor of success and possible complications [5]. Overestimation of the endodontic working length may cause overinstrumentation of the root canals, whereas underestimation of the working length may result in insufficient root canal preparation [6, 7]. The accuracy of radiographic methods of length determi- nation also depends on the radiographic technique used. Different studies concluded that tooth length determined by the bisecting angle technique, either correctly or incorrectly angulated, was less accurate than that by the paralleling Hindawi BioMed Research International Volume 2020, Article ID 7890127, 8 pages https://doi.org/10.1155/2020/7890127