Life-threatening cellulitis of submandibular and sublingual spaces; usu. starts in infected lower molar and involves connective tissue, fascia, and muscles. Brawny, painful edema occurs. Condition is seen in abscess, trauma, posterior lower molars, lupus, alcoholism, and immunodeficiency. 1/3 of patients need intubation or tracheotomy. Operative drainage should be done on an emergent/urgent basis with control of the airway on the first attempt critically important to eliminate life-threatening laryngospasm and edema with excessive manipulation.