title: Anatomical characteristics and visibility of mental foramen and accessory mental foramen: Panoramic radiography vs. cone beam CT.
abstract: BACKGROUND
  The mental foramen (MF) is a small foramen located in the anterolateral region of the mandible through which the mental nerve and vessels emerge. The knowledge on the anatomic characteristics and variations of MF is very important in surgical procedures involving that area. The aim of this study was two-fold: firstly, to analyze the anatomic characteristics of MF and the presence of accessory mental foramen (AMF) using CBCT and, secondly, to compare the capability of CBCT and PAN in terms of MF and AMF visualization, as well as influencing factors.
  
  
  METHODS
  A sample of 344 CBCT scans was analyzed for presence and characteristics (i.e. diameter, area, shape, exit angle) of MF and AMF. Subsequently, corresponding PANs were analyzed to ascertain whether MF and AMF were visible.
  
  
  RESULTS
  Out of the 344 patients, 344 (100%) MFs and 45 (13%) AMFs were observed on CBCT. Regarding gender, MF diameter and area, MF-MIB and MF-MSB distances, and exit angle were all significantly higher in males. Also, statistically significant differences were found in terms of age and dental status. Statistically significant differences in MF long and short diameters and MF area were found with respect to AMF presence (p=.021, p=.008, p=.021). Only 83.87% of the MFs and 45.83% of the AMFs identified on CBCT were also visible on PANs. MF diameter, shape, exit angle, and age had a significant influence on MF visualization on PAN (B=.43, p=.005; B=-.55, p=.020; B=.20, p=.008; B=.61, p=.005).
  
  
  CONCLUSIONS
  PAN is not an adequate technique to properly identify MF and AMF. Diameter, shape, exit angle, and age are all factors influencing MF visualization on PAN images. For surgery involving the MF anatomical region, a preoperative radiological study with CBCT is of crucial importance to avoid complications.
authors.affiliation: Stomatology Department, Medicine and Dentistry School, University of Santiago de Compostela, C/ Entrerrios S/N 15872, Santiago de Compostela, Spain, mariamercedes.suarez@usc.es.
authors.forename: Juan
authors.initials: J
authors.lastname: Muinelo-Lorenzo
authors.forename: Juan-Antonio
authors.initials: JA
authors.lastname: Suárez-Quintanilla
authors.forename: Ana
authors.initials: A
authors.lastname: Fernández-Alonso
authors.forename: Jesús
authors.initials: J
authors.lastname: Varela-Mallou
authors.forename: María-Mercedes
authors.initials: MM
authors.lastname: Suárez-Cunqueiro
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D008875:Middle Aged; D011862:Radiography, Panoramic; D055815:Young Adult