Identification of the Mental Neurovascular Bundle: A Comparative Study of Panoramic Radiography and Computer Tomography Andrea Forni, DDS,* M. Angeles Sánchez-Garcés, MD, DDS, PhD,† and Cosme Gay-Escoda, MD, DDS, PhD‡ C orrect placement of dental implants in the mandibular mental region may be limited by the intraosseous path of the mental neurovascular bundle. Location and morphology of this anatomic structure need to be considered before implant surgery is undertaken. In total edentulism cases, the inter- mental foramina region is used for the design of different types of prostheses, such as overdentures, hybrid, or fixed bridges. 1,2 Thus, it is very important to identify the morphology and size of the mental nerve to decide on an adequate surgical treatment plan that would prevent the risk of nerve damage. The intraosseous morphology pattern of the mental nerve may be a problem when it proceeds as an “anterior loop,” defined as “an extension of the inferior alveolar nerve, anterior to the mental foramen, before exiting the canal.” 3 This type of nerve morphology affects the possibility to install a hybrid or fixed prosthesis supported by 4 or 5 intermental implants. 3,4 In such cases, the possibility of using a fixed-retained implant-supported prosthesis is a well- accepted alternative in terms of patient comfort and is based on documented high success rates and a high relation- ship cost/benefits. 1,2,5 To study the anatomic aspects of this region and develop a treatment plan, several diagnostic techniques have been proposed as complementary to physical examination. 6 Frequently, panoramic radiogra- phy (PR) is the only preoperative imaging technique used in daily prac- tice. One of the disadvantages of pan- oramic images is the distortion and magnification of the anatomical struc- tures that commonly results in either over- or underestimation of the real size. 7,8 Other diagnostic techniques, such as intraoral periapical radiographs and computed tomography (CT), do not allow exact measurements. Neverthe- less, CT provides more reliable data and can be used to obtain detailed informa- tion using a three-dimensional analysis. 9 The aim of this study was to describe the size of the mental neuro- vascular canal and to compare the measurements obtained from PR with those from CT. The study was carried out by 2 independent examiners for assessing inter-examiner agreement to *Fellow of Oral Surgery and Orofacial Implantology, School of Dentistry, University of Barcelona, Barcelona, Spain. †Professor of Oral and Maxillofacial Surgery, Master’s Degree Program in Oral Surgery and Implantology, School of Dentistry, University of Barcelona, Barcelona, Spain; Researcher of the UB-IDIBELL Institute, Barcelona, Spain. ‡Professor and Chairman of Oral and Maxillofacial Surgery Department, Director of Master’s Degree Program in Oral Surgery and Implantology, School of Dentistry, University of Barcelona, Barcelona, Spain; Researcher, Bellvitge Institute for Biomedical Research, Barcelona, Spain; Oral and Maxillofacial Surgeon, Teknon Medical Center, Barcelona, Spain. Reprint requests and correspondence to: Cosme Gay-Escoda, DDS, MD, PhD, Centro Médico Teknon C/Vilana 12, 08022 Barcelona, Spain, Phone: 93-402- 42-74, Fax: 93-393-31-70, E-mail: cgay@ub.edu ISSN 1056-6163/12/02106-516 Implant Dentistry Volume 21  Number 6 Copyright © 2012 by Lippincott Williams & Wilkins DOI: 10.1097/ID.0b013e318272ff1a Objectives: To compare the images of the mental canal in pan- oramic radiography (PR) and com- puted tomography (CT) by analyzing the concordance with diagnostic tests and examiners. Material and Methods: The position of the mental foramen (MF), distance to the lower mandib- ular border, anterior length of the mental loop (ML), agreement between examiners and diagnostic concordance were registered in 50PR and 50CT. Results: ML was identified (34.5/41%, PR/CT). PR magnifica- tion was 36.6% higher than in CT. The anterior extension and distance to the inferior border of the MF was higher for PR (2–6.2 mm). Inter- examiner agreement on CT was good (k ¼ 0.628) and very good on PR (k ¼ 0.845). Conclusion: There is a magnifi- cation (36.6%) of the images in PR with respect to the CT. Identification of MF and ML is not related to the bone quality. Inter-examiner agree- ment is better on PR. (Implant Dent 2012;21:516–521) Key Words: mental loop, mental nerve, mental canal, radiology, pre- operative implant planning, image distortion 516 IDENTIFICATION OF THE MENTAL NEUROVASCULAR BUNDLE  FORNI ET AL