Classification of the lingual foramina and their bony canals in the median region of the mandible. Cone beam computed tomography observations of dry Japanese mandibles

We investigated the lingual foramina and their bony canals in the median region of the mandible using cone beam computed tomography (CBCT). Sixty-eight dry Japanese mandibles were studied. The mandibles were set parallel to the inferior mandibular plane, and CBCT images of the medial region were obtained. The lingual foramina in the medial region (MLFs) were classified as being on the midline superior to the mental spine (s-MLF), on the midline inferior to the mental spine (i-MLF), or beside the midline (a-MLF). The frequency, location, and angulation of each foramen and its canal were measured from the CBCT images. The s-MLF, i-MLF, and a-MLF occurred with frequencies of 86.8%, 83.8%, and 42.6%, respectively. The respective distances from the inferior mandibular plane were 11.4, 4.4, and 5.7 mm, while the vertical angulation of the canals was 77.5 deg, 114 deg, and 114 deg. A significant relationship was observed between the foramen height and canal angulation. On dissecting six cadaver mandibles, the sublingual artery was identified in s-MLFs and i-MLFs, while anastomosis of the sublingual and submental arteries was found in the a-MLFs. MLFs were observed frequently, and we confirmed that arteries passed though their canals. Since s-MLFs were the most frequent, contained the artery, and were located superior to the other MLFs, clinicians should identify such foramina from preoperative images. (author)