Clinical Study Radiographic and Clinical Findings of Single-Visit Root Canal Treatments with Apical Enlargement in Necrotic Teeth: A Retrospective Cohort Study Tan F. Eyüboğlu , 1 Keziban Olcay , 2 Erhan Erkan , 1 and Mutlu Özcan 3 1 Faculty of Dentistry, Department of Endodontics, Istanbul Medipol University, Istanbul, Turkey 2 Faculty of Dentistry, Department of Endodontics, Istanbul University Cerrahpaşa, Istanbul, Turkey 3 Division of Dental Biomaterials, Clinic for Reconstructive Dentistry, University of Zurich, Zurich, Switzerland Correspondence should be addressed to Tan F. Eyüboğlu; tfeyuboglu@yahoo.com Received 10 May 2020; Revised 8 August 2020; Accepted 25 August 2020; Published 28 September 2020 Academic Editor: Stefano Curcio Copyright © 2020 Tan F. Eyüboğlu et al. 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. This study evaluated the long-term clinical outcomes of single-visit root canal treatments with apical enlargement on patients with necrotic pulp tissue retrospectively. A total of 137 teeth with necrotic pulp tissue which underwent single-visit root canal treatments were included. The root canals were shaped up until the apical constriction, which was determined by an apex locator. The outcomes were evaluated by two independent and calibrated endodontists clinically and radiographically. Teeth were dichotomized into healed (PAI ≤ 2, no signs or symptoms) and nonhealed (PAI > 2, with/without signs or symptoms) groups. Each patients’ preoperative PAI and lesion size were recorded to evaluate the preoperative periapical status as well as several other prognostic factors. Statistical analyses were performed (p =0:05) on ninety teeth. The mean observation time was 60 months. Out of ninety teeth, 87 (96.7%) were healed and 3 (3.3%) were nonhealed. No correlations were found between the prognostic factors and the outcomes (p >0:05). Cohen’s kappa and Gwet’s agreement coefficient scores between the preoperative PAI scores and preoperative lesion sizes showed good agreements, with values of 0.834 and 0.898, respectively. Apical enlargement is a viable treatment option for single-visit root canal treatments. 1. Introduction The primary goal of endodontic therapy is to promote heal- ing and prevent apical periodontitis in the periapical area [1] where chemomechanical cleaning is essential for this pur- pose [2]. In a recent study, achieving a successful root canal treatment was associated with high-quality root canal filling and postendodontic restoration and the latter was reported to be mandatory for a healthy periapical tissue [3]. The high prevalence of bacterial biofilms and the presence of anatom- ical complexities, such as ramifications and lateral canals, have been proven to make the apical third of the root canal a challenging area for cleaning and disinfection to achieve high-quality root canal filling. These complexities can cause both persistent infections and compromised outcomes [4]. The prevention of these poor outcomes has contributed to the creation of a sound and scientifically supported approach to apical enlargement, which can be described as the enlarge- ment of apical third of the root canal, during root canal treat- ment in order to reduce the intracanal bacteria level [2] and achieve better healing results [5]. However, there is still no consensus on where the apical enlargement should end, with measurements varying from 0.5 to 1 mm short of the apex, at the apex, and beyond the apical foramen [2–6]. Moreover, the extension of apical enlargement in means of final file size has not reached a consensus either. Traditionally, using three sizes larger than first apical binding file was recommended for apical shaping [7]. However, this approach was indicated to be inadequate [8] due to the anatomy of apical region [9]. The files that bound at the working length were also reported Hindawi BioMed Research International Volume 2020, Article ID 7912638, 10 pages https://doi.org/10.1155/2020/7912638