Fenestration of the mandibular buccal cortex by the inferior alveolar neurovascular bundle

It has been observed that the presence of anatomical variations in the mandible is frequently overlooked in clinical management. The aim of this article is to describe two rare clinical cases of fenestration of the mandibular buccal cortex by the inferior alveolar bundle, detected by cone beam computed tomography (CBCT).

The first case was a 58-year-old female patient who was referred to the private clinic for rehabilitation with dental implants. The patient underwent an examination by CBCT (Kodak 9000, Carestream Health, Rochester, NY, USA) to assess the bone quality and quantity for placement of dental implants in the edentulous regions. In cross-sectional slices and in 3D reconstructions of the left mandible ( Fig. 1 ), it was observed that the mandibular canal lacked cover by the buccal cortex.

Fig. 1
CBCT images of the left mandibular body showing fenestration of the mandibular buccal cortex by the inferior alveolar bundle in 3D reconstruction (A, black arrow) and cross-sectional slices (B, white arrows).

The second case was a 68-year-old male patient who was referred to the department of oral surgery for placement of dental implants in the posterior regions of the mandible. Preoperative panoramic radiography revealed normal shape, size, and course of the mandibular canals, thus no significant alterations were observed ( Fig. 2 ). The patient underwent an examination by CBCT (Kodak 9000). In this examination fenestrations of the mandibular buccal cortex were observed – bilateral in the retromolar region ( Fig. 3 ).

Fig. 2
Panoramic radiography of the case, showing normal mandibular canals.

Fig. 3
3D reconstruction and cross-sectional slices of the right (A) and left (B) mandibular bodies, showing fenestration of the mandibular buccal cortex by the inferior alveolar bundle (black and with arrows).

The presence of anatomical variations associated with the mandibular canal has great clinical implications during surgical procedures such as dental implant placement, orthognathic surgery, lower third molar extraction, and sagittal mandibular osteotomies. Inaccuracy in locating anatomical variations in the mandible can result in injury to the inferior alveolar neurovascular bundle (IANB), such as traumatic neuroma, paresthesia, anaesthesia, and haemorrhage.

In the present cases, it was not possible to determine if the IANB was exposed. Instead, we believed the IANB to be covered by the periosteum and to be safe from all procedures except those including elevation of the periosteum (e.g. extraction of impacted third molars and sagittal split ramus osteotomies) and in cases of orthognathic surgery (metal plates are fixed in the buccal cortex).

A PubMed search was conducted (articles published in the English language literature, Table 1 ) in order to review case reports of fenestration in the buccal cortex by the inferior neurovascular bundle. Only two cases of fenestration of the mandibular buccal cortex by the IANB have been described, both confirmed by computed tomography (CT). In those cases, the fenestrations were associated with pathological processes. However, the present cases are the first in the literature showing a true absence of mandibular buccal cortex by the IANB without any association with pathological processes.

Jan 24, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Fenestration of the mandibular buccal cortex by the inferior alveolar neurovascular bundle
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