The traumatic oral ulcer is very common and can be caused by acute or chronic trauma from sharp objects, accidental or intentional biting, or overzealous brushing. The ulcer is usually solitary and can range from less than 1 mm to more than 1 cm in diameter. Typically the patient complains of mild pain during the first few days following the episode of trauma. With removal of the cause, healing takes place within 2-7 days. A superimposed candidal infection can impede healing, even in healthy patients. Sites commonly injured by the teeth include the tongue, lips, and buccal mucosa. Ulcers on the gingiva, palate and mucobuccal fold are usually related to hard, sharp edges of food or to toothbrush-induced injury. Thorough questioning of the patient may suggest the diagnosis.

The lesion appears as a round, ovoid or irregularly shaped removable, creamy-white fibrinopurulent membrane surrounded by a variable amount of erythema. For more chronic lesions, a white border of hyperkeratosis, the margins of which blend with the surrounding mucosa, is adjacent to the area of ulceration.