388 Volume 28, Number 2, 2013 T he mandibular canal is a bilateral, intraosseous pathway that carries the inferior alveolar nerve from the mandibular foramen to the mental foramen, providing innervation to the teeth of the anterior man- dible, the soft tissues adjacent to the foraminal area, and the integument of the chin. 1,2 Anatomical variations in the path of the mandibu- lar canals, such as bifd canals and anterior loops of the mental nerve, are common (Fig 1). 3,4 This consid- eration becomes important when planning surgical procedures of the anterior mandible, such as oste- otomy, bone harvesting, and the placement of dental implants. Although these are generally considered to be safe elective procedures, 1,2,5,6 sensory disturbance has been reported as a complication in up to 37% of patients in the frst 2 weeks following surgery, with 10 to 15% of patients continuing to complain of problems after 15 months. 6,7 Sensory disturbance occurs most commonly after placement of a mandibular fxed pros- thesis between the mental foramina. This is because biomechanical considerations dictate that the distal margin of the implants should be as close as possible to the mental foramen so as to reduce the length of the distal cantilever, which increases the risk of injury, particularly in cases where a loop of the inferior alveo- lar nerve is present. A variety of mechanisms may explain sensory distur- bance following surgery to the anterior mandible. For example, direct surgical trauma to the mental nerve during surgery can result in either transient or persis- tent paresthesia, anesthesia, or even disabling dyses- thesia most often afecting the lip and chin region. 8,9 Similarly, sensory disturbance due to direct damage of the incisive nerve has been reported in 17% of pa- tients after the placement of implants in the anterior mandible. 10 Indirect damage secondary to hematoma 1 Professor, Department of Implantology, São Leopoldo Mandic Institute and Research Center, Campinas, SP, Brazil. 2 Professor, Department of Restorative Dentistry of Dental School of Federal University of Juiz de Fora and Departament of Implantology, São Leopoldo Mandic Institute and Research Center, Campinas, SP, Brazil. 3 PhD Student, Department of Implantology, São Leopoldo Mandic Institute and Research Center, Campinas, SP, Brazil. Correspondence to: Dr Marcio Borges Rosa, Av. Do Contorno 4849/4 andar, Belo Horizonte, Minas Gerais, Brasil, 30.110-080. Email: marcio@implantare.com.br ©2013 by Quintessence Publishing Co Inc. Retrospective Study of the Anterior Loop of the Inferior Alveolar Nerve and the Incisive Canal Using Cone Beam Computed Tomography Marcio Borges Rosa, DDS, Ms, PhD 1 /Bruno Salles Sotto-Maior, DDS, Ms, PhD 2 / Vinícius de Carvalho Machado, DDS 3 /Carlos Eduardo Francischone DDS, Ms, PhD 1 Purpose: The mental foramen is an important landmark during surgical procedures such as osseous grafting or the placement of dental implants. To avoid injuring the mental nerve, it is important both to carefully assess the location of the mental foramen and to determine whether an anterior loop of the mental nerve or the incisive canal lies mesial to it. The objective of this study was to quantify the ability of cone beam computed tomography (CBCT) to measure the length of the mental nerve loop, the length and diameter of the incisive nerve canals, and the incisive canal path. Materials and Methods: The study included 352 CBCT scans that had originally been used for preoperative planning of implant placement in the interforaminal region of the anterior mandible. For each scan, the length of the mental nerve loop and the length, diameter, and path of the incisive canal were determined. Mean values were compared between groups based on sex, right versus left side, and whether the patient was edentulous. Results: The inferior alveolar nerve loop and incisive canal had a mean length of 2.40 ± 0.93 mm and 9.11 ± 3.00 mm, respectively. The mean incisive canal diameter was 1.48 ± 0.66 mm and showed a downward path in 51.3% of CBCT images and a linear or upward path in 38.29% and 10.41% of scans, respectively. Conclusions: CBCT provides an accurate means to identify critical anatomical features in the anterior mandible during preoperative surgical planning. J ORAL MAXILLOFAC IMPLANTS 2013;28:388–392. doi: 10.11607/jomi.2648 Key words: anterior loop, cone beam computed tomography, dental implant © 2013 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.