Gaining surgical access for repositioning the inferior alveolar neurovascular bundle

Abstract

This study is aimed at determining anatomical landmarks that can be used to gain access to the inferior alveolar neurovascular (IAN) bundle. Scanned CBCT (i-CAT machine) data of sixty patients and reconstructions performed using the SimPlant dental implant software were reviewed. Outcome variables were the linear distances of the mandibular canal to the inferior border and the buccal cortex of the mandible, measured immediately at the mental foramen (D1) and at 10, 20, 30, and 40 mm (D2-D5) distal to it. Predictor variables were age, ethnicity, and gender of subjects. Apicobasal assessment of the canal reveals that it is curving downward towards the inferior mandibular border until 20 mm (D3) distal to the mental foramen where it then curves upwards, making an elliptic-arc curve. The mandibular canal also forms a buccolingually oriented elliptic arc in relation to the buccal cortex. Variations due to age, ethnicity, and gender were evident and this study provides an accurate anatomic zone for gaining surgical access to the IAN bundle. The findings indicate that the buccal cortex-IAN distance was greatest at D3. Therefore, sites between D2 and D5 can be used as favorable landmarks to access the IAN bundle with the least complications to the patient.

Figure 1

Cross-sectional sagittal view of a CBCT image showing the site for obtaining measurements. CL = crest of alveolar bone, B = distance between the mandibular canal and buccal cortex, I = distance between the mandibular canal and inferior body of mandible, and D = diameter of the mandibular canal.

Figure 2

Illustration shows the locations of the measurements at every 10 mm interval starting from the distal aspect of mental foramen backwards (D1–D5). (D1) is the location of the mandibular canal at the distal aspect of mental foramen. (D2) is the location of the mandibular canal at 10 mm away from D1 distally. (D3) is the location of the mandibular canal at 10 mm away from D2 distally. (D4) is the location of the mandibular canal at 10 mm away from D3 distally. (D5) is the location of the mandibular canal at 10 mm away from D4 distally.

Figure 3

Distances of the mandibular canal to the inferior border of mandible immediately at (D1) and at 10 (D2), 20 (D3), 30 (D4), and 40 (D5) mm distal to the mental foramen of 3 different ethnic groups. An elliptic-arc curve pattern is observed when the results were put together.

Figure 4

Distances of the mandibular canal to the buccal and inferior cortices of mandible immediately at (D1) and at 10 (D2), 20 (D3), 30 (D4), and 40 (D5) mm distal to the mental foramen of 3 different ethnic groups. A 3D elliptic-arc curve appearance is observed when both results were put together.

Figure 5

Distances of the mandibular canal to the buccal cortex of mandible immediately at (D1) and at 10 (D2), 20 (D3), 30 (D4), and 40 (D5) mm distal to the mental foramen of 3 different ethnic groups. A buccolingual elliptic-arc curve pattern is observed in relation to the buccal cortex.

Figure 6

Superimposition of the findings of this study over a curved body of mandible displays differences in distance between various points of the MC to the buccal cortex.