Aphthous stomatitis caused by a reduction in numbers of CD4+ T cells may be implicated in RAS-type ulceration in HIV infection. The thickness of the mucosa may be an important factor in aphthous stomatitis. Usually, ulcers form on the thinner, non-keratinizing mucosal surfaces in the mouth. Factors which decrease the thickness of the mucosa increase the frequency of occurrence, and factors which increase the thickness of the mucosa correlate with decreased ulceration. The nutritional deficiencies associated with aphthous stomatitis (Vitamin B12, folate, and iron) can all cause a decrease in the thickness of the oral mucosa (atrophy). Local trauma is also associated
Stomatitis nicotina with tobacco use may be evident such as brown or black extrinsic staining of teeth from tar and other components of tobacco smoke. The cause of nicotine stomatitis is thought to be chemical or thermally induced keratosis. The chemicals in tobacco may act as irritants in this condition. Chronic heat exposure is also responsible. Pipe smoking produces more heat on the palate than any other forms of smoking. Long-term drinking of very hot beverages can also cause a similar condition. The severity of the changes correlates with the frequency of the habit. The prevalence depends on a society's use of