Aphthous stomatitis countries. Within nations, it is more common in higher socioeconomic groups. Males and females are affected in an equal ratio, and the peak age of onset between 10 and 19 years. About 80% of people with aphthous stomatitis first developed the condition before the age of 30. There have been reports of ethnic variation. For example, in the United States, aphthous stomatitis may be three times more common in white-skinned people than black-skinned people. "Aphthous affectations" and "aphthous ulcerations" of the mouth are mentioned several times in the treatise "Of the Epidemics" (part of the Hippocratic corpus, in the 4th
Aphthous stomatitis and other oral healthcare products, may produce oral ulceration in some individuals. It has been shown that aphthous stomatitis is more common in people using toothpastes containing SLS, and that some reduction in ulceration occurs when a SLS-free toothpaste is used. Some have argued that since SLS is almost ubiquitously used in oral hygiene products, there is unlikely to be a true predisposition for aphthous stomatitis caused by SLS. Aphthous-like ulceration may occur in association with several systemic disorders (see table). These ulcers are clinically and histopathologically identical to the lesions of aphthous stomatitis, but this type of oral ulceration