Localisation of the mental foramina
Meer, E. van der
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A fair amount of research covering the mental and accessory mental foramina in humans has been conducted because of their importance in dentistry. Information about the frequency and location of accessory mental foramina is important to prevent damage to the mental nerves and blood vessels during surgery. Little research has been done on this subject in veterinary dentistry, but accessory mental foramina have been reported. The aims of this study were to identify the prevalence of a caudal mental foramen, to determine what the exact location is of the middle and caudal mental foramina and to determine whether intraoral radiography (IOR) is an efficient method of imaging the mental foramina, compared to computed tomography (CT). Materials and Methods: IOR of 53 dogs were assessed retrospectively. There were seven dogs that underwent both IOR and CT. An additional 140 dogs were included for retrospective assessment of CT examinations. For both CT and IOR the number of the foramina and the ease of identification (difficult, easy, excellent) was scored. Location was determined on CT and on parallel views of IOR. The scores for ease of identification of the CT images were com-pared with the scores of the IOR. Results: It was found that the presence of a rostral, middle and caudal mental foramen is the most common, namely in 65.5% for the left side (L) and 68.3% for the right side (R) of the cas-es on CT. Dogs have also been found with 2, 4, 5 and 6 foramina on one side. The middle mental foramen was mostly located in the area around 305-306 and 405-406. In 37.1 to 39.3% of the cases the foramen was located apical of both -05 and -06, in 22.1 to 27.2% it was locat-ed between -05 and -06. The caudal mental foramen was mostly located apical of the -07. Fo-ramina were excellent to identify most often on CT, in 82.9% (L) and 86.4% (R) of the cases, compared to 11.3% (L) and 18.9% (R) of the cases on IOR. Whereas foramina were difficult to identify on IOR in 24.5% (L) and 22.6% (R), compared to 1.4% (only L) on CT. In addition, the results showed that dogs weighing up to 10kg have significantly less foramina on the right than dogs weighing > 10kg. Conclusion: The vast majority of dogs have three (rostral, middle and caudal) mental foramina on either side. Locations of the mental foramina left and right are comparable but there is some variation. CT appears to be a more efficient method to visualize the mental foramina compared to IOR. In addition, it has been found that the size of the dog affects the number of foramina. This effect has only been found on the right side.