An assessment on spiral CT scan of the superior and inferior genial spinal foramina and canals.

To characterise the superior as well as the inferior genial spinal foramen and their bony canal using a large CT data sample. The study included 555 mandibular spirals CT scans, taken from patients for pre-operative implant planning. Basic observation by three observers included the number of canals, their respective anatomical location and morphological variations. Furthermore, linear measurements were performed to describe the foramina and canal characteristics. On spiral CT scans, the superior and inferior genial spinal foramina were detected in 448 CT scans (81%). In 29% of the mandibular CTs, two or more midline canals were noted. 47% of the foramina were located in a position inferior to the genial spines; the others were located in a superior position. The mean (SD) lingual and buccal diameters of the canal structures were 0.73 (0.27) and 0.54 (0.29) mm, respectively with an average length of 3.94 (1.29) mm. The canal was located on average 7.40 (5.31) mm from the mandibular base at the lingual entrance and 7.96 (3.47) mm at the buccal canal end point. The average canal extended towards the buccal bone for an average 37% of the bone width. The results demonstrated the presence of both superior and inferior genial spinal foramina, with 29% of the individuals having double foramina. About 53% of the foramina was located superior to the genial spines. Considering its neurovascular content, these foramina should be carefully evaluated during pre-operative planning.