Measurements of mandibular canal region obtained by cone- beam computed tomography: a cadaveric study Kıvanç Kamburog ˘lu, DDS, MSc, PhD, a Cenk Kılıç, MD, b Tuncer Özen, DDS, PhD, c and Selcen Pehlivan Yüksel, MS, d Ankara, Turkey ANKARA UNIVERSITY AND GU ¨ LHANE MILITARY MEDICAL ACADEMY Objective. The objective of this study was to assess the accuracy and reproducibility of cone-beam CT measurements of specific distances around the mandibular canal by comparing them to direct digital caliper measurements. Methods. Six formalin-fixed hemimandible specimens were examined using the ILUMA cone-beam CT system. Images were obtained at 120 kVp, 3.8 mA, and a voxel size of 0.2 mm, with an exposure time of 40 seconds. Specimens were cut into sections at 7 locations using a Lindemann burr, and a digital caliper was used to measure the following distances on both the anterior and posterior sides of each section: Mandibular Width (W); Mandibular Length (L); Upper Distance (UD); Lower Distance (LD); Buccal Distance (BD); and Lingual Distance (LID). The same distances were measured on the corresponding cross-sectional cone-beam CT images using the built-in measurement software. All caliper and cone-beam CT measurements were made by 2 independent trained observers and were repeated after an interval of 1 week. The Bland/Altman method was used to calculate intra- and inter-rater reliability. Intra-class correlation coefficients (ICCs) from 2-way random effects model were calculated. Agreements between cone-beam CT and direct digital caliper were calculated by ICC for 6 distances and 2 observers. Results. Intraobserver and interobserver measurements for all distances showed high agreement. ICCs for intraobserver agreement ranged from 0.86 to 0.97 for cone-beam CT measurements and from 0.98 to 0.99 for digital caliper measurements. ICCs between observers ranged from 0.84 to 0.97 for the cone-beam CT measurements and from 0.78 to 0.97 for the digital caliper measurements. ICCs for cone-beam CT and direct digital caliper ranged from 0.61 to 0.93 for the first observer and from 0.40 to 0.95 for the second observer. Conclusion. Accuracy of cone-beam CT measurements of various distances surrounding the mandibular canal was comparable to that of digital caliper measurements. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;107: e34-e42) The introduction of new technologies in the field of dental radiology has made it possible for the clinician to more accurately evaluate dental structures and conduct precise preoperative planning. In recent years, cone- beam computed tomography (CT) units have gained considerable importance, and a series of units have been developed for the 3-dimensional (3D) assessment of the dento-maxillofacial region. Cone-beam CT units center a cone-shaped x-ray beam on an area or panel detector, allowing them to generate a scan of the entire head with a single rotation of the gantry. The use of cone-beam CT technology in dento-maxillofacial im- aging provides a number of potential advantages over conventional CT, including x-ray beam collimation, reduced effective doses, and fewer artifacts. 1-4 Surgical procedures such as third molar surgery, implant placement, osteotomy and fracture repair that involve structures adjacent to the mandibular canal require exact knowledge of the intraosseous course of the canal and neurovascular bundle in order to avoid a high risk of injury. 5,6 In particular, distances between the mandibular canal and dental implants or prostheses are so small as to require preoperative evaluation that includes precise measurements with an error of less than 1 to 2 mm. 7,8 Before endosseous implants are inserted in the mandible, the clinician must obtain accurate measurements of the distances surrounding the mandibular canal. 9 Cone-beam CT has proved useful in the preoperative evaluation of patients undergoing den- tal implantation 10,11 and other surgical procedures near the mandibular canal, reducing the likelihood of injury to the neurovascular bundle. 12-15 However, considering the relative newness of the technology, further assess- a Doctor, Ankara University, Faculty of Dentistry, Department of Oral Diagnosis and Radiology, Ankara, Turkey; and Gülhane Military Medical Academy, Dental Science Center, Department of Oral Di- agnosis and Radiology, Etlik, Ankara, Turkey. b Doctor, Gülhane Military Medical Academy, Faculty of Medicine, Department of Anatomy, Etlik, Ankara, Turkey. c Associate Professor, Gülhane Military Medical Academy, Dental Science Center, Department of Oral Diagnosis and Radiology, Etlik, Ankara, Turkey. d Instructor, Ankara University, Faculty of Medicine, Department of Biostatistics, Ankara, Turkey. Received for publication Aug 5, 2008; returned for revision Sep 10, 2008; accepted for publication Oct 16, 2008. 1079-2104/$ - see front matter © 2009 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2008.10.012 e34