Stomatitis washes away antigens and acts as a barrier. The oral mucosa is also more vascular (has a better blood supply) than skin, meaning that any antigens are more quickly removed from the area by the circulation. Finally, there is substantially less keratin in oral mucosa, meaning that there is less likelihood that haptens will form. Allergic contact stomatitis appears as non-specific inflammation, so it may be mistaken for chronic physical irritation. There may be burning or soreness of the mouth and ulceration. Chronic exposure to the allergen may result in a lichenoid lesion. Plasma cell gingivitis may also occur, which
Aphthous stomatitis vitamin supplements only infrequently improve the ulceration. The relationship to vitamin B12 deficiency has been the subject of many studies. Although these studies found that 0–42% of those with recurrent ulcers suffer from vitamin B12 deficiency, an association with deficiency is rare. Even in the absence of deficiency, vitamin B12 supplementation may be helpful due to unclear mechanisms. Hematinic deficiencies can cause anemia, which is also associated with aphthous-like ulceration. Gastrointestinal disorders are sometimes associated with aphthous-like stomatitis, e.g. most commonly Celiac disease, but also inflammatory bowel disease such as Crohn's disease or ulcerative colitis. The link between gastrointestinal disorders