Surg Radiol Anat (2010) 32:927–931 DOI 10.1007/s00276-010-0645-1 123 ORIGINAL ARTICLE A simple method to locate mandibular foramen: preliminary radiological study Olivier Trost · Vivien Salignon · Nicolas Cheynel · Gabriel Malka · Pierre Trouilloud Received: 27 December 2009 / Accepted: 23 February 2010 / Published online: 10 March 2010  Springer-Verlag 2010 Abstract Introduction The position of mandibular foramen is vari- able at the medial aspect of mandibular ramus. Neverthe- less its location is useful for the oral and maxillofacial surgeon in orthognatic surgery, especially in vertical ramus osteotomy (VRO) procedure. The aim of our study is to analyse the position of mandibular foramen in order to pro- vide simple and reliable surgical landmarks. Materials and methods A radio-anatomical study was undertaken on normal mandibular panoramic X-ray exam- inations. Precise reproductions were outlined on tracing paper. Original orthonormal landmark was designed using posterior border of the ramus, mandibular incisure and anterior border of the ramus. All these elements are visible in the patient in VRO. Measurements of the position of mandibular foramen in horizontal and vertical dimensions were then performed with a ruler by two independent observers: l (width of mandibular branch), x (distance between posterior border of the ramus and mandibular fora- men), h (height of mandibular branch) and y (distance between sigmoid notch and mandibular ramus). x/l and y/h ratios were calculated in order to minimise magniWcations and image distortions due to the imaging process. Results Forty-six panoramic X-rays were analysed, includ- ing 24 male and 22 female specimens (sex-ratio 1.1/1) with the mean-age 21 years. In vertical dimension, y/h ratio was distributed on a gaussian mode with a peak around 0.30–0.35, mandibular foramen was located around the midpoint of the inferior two-thirds and the superior third of the ramus, preferentially under this point. In horizontal dimension, x/l ratio observed the same model with a peak around 0.35; mandibular foramen was located around the midpoint of the anterior two-thirds and the posterior third of the ramus, preferentially in front of this point. Mandibu- lar foramen was situated in the ventral and inferior two- thirds of the ramus without diVerence according to the side, sex or age. Discussion Posterior and superior thirds of the ramus constitute a “safety zone” where mandibular foramen is unlikely to be found. This area can be used by the oral and maxillofacial surgeon in vertical ramus osteotomy of the mandible with low inferior alveolar nerve morbidity proba- bility. Keywords Mandible · Foramen · Anatomy · Orthognatic · Surgery Introduction Treatment of craniofacial dysmorphism is the Weld of orthognatic surgery. ModiWcation of the position of the mandible requires bifocal osteotomy; nowadays the gold standard is the intra-oral biangular sagittal split osteotomy introduced by Trauner and Obwegeser in 1957 [8] and modiWed by Dal Pont in 1959 [1]. Nevertheless in case of hypotrophic or dysplastic mandible, vertical ramus osteot- omy may be indicated [7]: the osteotomy is performed behind mandibular foramen. According to this technique, lateral aspect of the ramus is approached through cutaneous O. Trost (&) · V. Salignon · N. Cheynel · P. Trouilloud Laboratory of Anatomy, INSERM U-887 “Motricité Plasticité”, Faculty of Medicine, University of Burgundy, Dijon, France e-mail: olivier.trost@chu-dijon.fr O. Trost · G. Malka Department of Oral and Maxillofacial Surgery, Teaching Hospital, Dijon, France