A comparative study on the location of the mandibular foramen in CBCT of normal occlusion and skeletal class II and III malocclusion

During the orthognathic surgery, it is important to know the exact anatomical location of the mandibular foramen to achieve successful anesthesia of inferior alveolar nerve and to prevent damage to the nerves and vessels supplying the mandible.

Cone-beam computed tomography (CBCT) was used to determine the location of the mandibular foramen in 100 patients: 30 patients with normal occlusion (13 men, 17 women), 40 patients with skeletal class II malocclusion (15 men, 25 women), 30 patients with skeletal class III malocclusion (17 men, 13 women).

The distance from the anterior border of the mandibular ramus to mandibular foramen did not differ significantly among the three groups, but in the group with skeletal class III malocclusion, this distance was an average of 1.43 ± 1.95 mm longer in the men than in the women (p < 0.05). In the skeletal class III malocclusion group, the mandibular foramen was higher than in the other two groups and was an average of 1.85 ± 3.23 mm higher in the men than in the women for all three groups combined (p < 0.05). The diameter of the ramus did not differ significantly among the three groups but was an average of 1.03 ± 2.58 mm wider in the men than in the women for all three groups combined (p < 0.05). In the skeletal class III malocclusion group, the ramus was longer than in the other groups and was an average of 7.9 ± 3.66 mm longer in the men than women.

The location of the mandibular foramen was higher in the skeletal class III malocclusion group than in the other two groups, possibly because the ramus itself was longer in this group. This information should improve the success rate for inferior alveolar nerve anesthesia and decrease the complications that attend orthognathic surgery.