What is Life threatening haemorrhage

Life threatening haemorrhage has been reported when a drill perforates the sublingual region of the mandible and injures the sublingual artery (branch of lingual artery). Upper airway obstruction secondary to severe bleeding in the floor of the mouth has been occasionally reported as a rare but potentially fatal complication of implant surgery. Excessive bleeding and formation of massive lingual, sublingual, and submandibular hematomas as a result of arterial trauma that occurred during the osteotomy preparation have the tendency of displacing the tongue and floor of the mouth to obstruct the airway.

The arterial bleeding in the floor of the mouth  may be due to injury to lingual artery( which stops when tongue is pulled out) or submental artery( branch of facial artery) which is stopped by placing pressure over the facial artery notch anterior to the mandibular angle.