The inter-foraminal region of the human mandible is a common elective area for several dental surgery procedures due to its favourable anatomic conditions. Some of the procedures done in this region include insertion of endosseous dental implants, bone harvesting from the chin, genioplasty in orthognathic surgery and placement of screws during plating in management of facial fractures.

There have been reported cases of near fatal upper airway obstruction due to haemorrhage following implant placement in this area. Majority of them have been attributed to transection of the sublingual artery when a misdirected drill perforates the lingual cortex and damages the blood vessel within the surrounding soft tissues as it enters the mandibular midline lingual foramen (MMLF). This vessel retracts into the floor of the mouth where a haematoma forms in the sublingual and submandibular spaces leading to a compromise of the airway, by swelling and pushing of the tongue against the palate.

This foramen is a constant finding and has an intra-osseous part, midline mandibular lingual canal (MMLC), which contains a blood vessel that is prone to transection during routine dental implant placement. It has been found that vessels travelling horizontal to the direction of an implant drill, but perpendicular to the spin of the drill, are at the greatest risk of laceration and transection.

A higher risk of trauma exists in some situations like where the alveolar ridge is severely resorbed, or where trimming of the ridge has to be done either to reduce excess bone or to create a flat site for drilling, because this procedure brings the MMLC closer to the superior aspect of the mandible. Drilling deeper into an extraction socket to obtain primary implant stability is now an acceptable procedure which increases the risk of bleeding. Some clinical protocols require inter-foraminal implant placement, which may lead to placement of an implant in the mandibular midline position.

There are two main sources of arterial blood supply to the anterior lingual area of the mandible: the submental and the lingual arteries. There is however lack of consensus as to the origin of the artery that enters the MMLF. Some authors have reported that it is a branch of the lingual artery and others the submental artery, while others have found that the vessel is an anastomosis of the two arteries. The possibility of existence of anastomoses and the lack of consensus as to the source of the artery that enters the MMLF pose a dilemma of whether the submental or the lingual artery should be ligated first in the event an extra-oral approach is required to control haemorrhage.

There is hardly any published data on the artery that enters the MMLF. This study aimed at determining the source of the artery that enters the MMLF. It was hoped that this finding would help the surgeon to precisely ligate the feeder vessel, should there be haemorrhage during placement of an inter-foraminal dental implant.