A<unk>  (aphtha) is an ulcer that occurs on the mucous membrane of the oral cavity.<unk> s are very common, occurring in association with many diseases and by many different mechanisms, but usually there is no serious underlying cause. Rarely, a<unk>  that does not heal may be a sign of oral cancer. These ulcers may form individually or multiple ulcers may appear at once (i.e., a "crop" of ulcers). Once formed, an ulcer may be maintained by inflammation and/or secondary infection. The two most common causes of oral ulceration are local trauma (e.g. rubbing from a sharp edge on a broken filling or braces, biting one's lip, etc.) and aphthous stomatitis ("canker sores"), a condition characterized by recurrent formation of oral ulcers for largely unknown reasons.<unk> s often cause pain and discomfort and may alter the person's choice of food while healing occurs (e.g. avoiding acidic, sugary, salty or spicy foods and beverages).
Mouth ulcer
Geographic tongue
Stercoral ulcer
Dental abscess
Callous ulcer
Pouchitis
Skin fissure
Tropical ulcer