Orthod Craniofac Res. 2017;1–10. wileyonlinelibrary.com/journal/ocr | 1 © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Accepted: 3 September 2017 DOI: 10.1111/ocr.12205 ORIGINAL ARTICLE Accuracy and reliability of landmark-based, surface-based and voxel-based 3D cone-beam computed tomography superimposition methods A. Ghoneima 1,2,3 | H. Cho 2 | K. Farouk 3 | K. Kula 2 1 Department of Orthodontics, Hamdan Bin Mohammed College of Dental Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences (MBRU), Dubai, United Arab Emirates 2 Department of Orthodontics and Oral Facial Genetics, Indiana University School of Dentistry, Indianapolis, IN, USA 3 Department of Orthodontics, Faculty of Dental Medicine, Al-Azhar University, Cairo, Egypt Correspondence A. Ghoneima, Department of Orthodontics and Oral Facial Genetics, Indiana University School of Dentistry, Indianapolis, IN, USA. Email: aghoneim@iu.edu Structured Abstract Objectives: To evaluate and compare the accuracy and reliability of 3 different meth- ods of three-dimensional cone-beam computed tomography scans (3D CBCTs) super- impositions: landmark-based, surface-based and voxel-based. Materials and Methods: Pre- and post-orthodontic treatment CBCTs (T1 and T2) of 20 subjects with a mean age of 11 years were obtained. Seven points on the zygo- matic arch and supraorbital region were selected to perform landmark-based superim- position. Surface-based and voxel-based superimpositions were performed using the anterior cranial base as a reference. Each superimposition method of T1 and T2 scans was repeated twice to assess the reliability. Accuracy of each technique was tested by superimposing duplicated sets of T1 scans. A total of 11 landmarks on the anterior cranial base, maxilla and mandible were located, and deviations of these landmarks on superimposed data were quantified to assess reliability and accuracy of all superimpositions. Results: There were no significant differences from zero when duplicated sets of T1 scans were superimposed using surface-based and voxel-based methods. Statistical significant differences were detected in several parameters when evaluating the ac- curacy of the landmark superimposition. Superimposition of T1 and T2 scans for test- ing the reliability revealed intraclass correlation coefficients greater than 0.90 for all measurements except for ACP-x and PNS-y of landmark-based method as well as ANS-x of voxel-based method. Conclusions: Surface-based and voxel-based superimposition methods using the ante- rior cranial base as a reference structure were accurate and reliable in detecting changes in landmark positions when superimposing. Landmark-based superimposition method was reliable but less accurate than the other methods. KEYWORDS accuracy, anterior cranial base, reliability, superimposition methods 1 | INTRODUCTION Analogue and digital imaging techniques to capture soft and hard tis- sues have long been a vital part of orthodontic diagnosis and treatment allowing analysis of facial profile, skeleton and dentition. 1 Many ortho- dontists are familiar with use of two-dimensional (2D) cephalometry. However, conventional 2D imaging has several limitations includ- ing lack of perspective, magnification, structural superimposition,