How is aphthous stomatitis (canker sore) diagnosed?

Aphthous stomatitis, or canker sore, is diagnosed by its appearance. The painful sores are small, round, and shallow; they're usually white or yellowish with a red rim. They're found on the soft tissue of the mouth or gums.

Your dentist can diagnose aphthous stomatitis, more commonly known as the canker sore, simply by looking inside your mouth. Canker sores are easily identified by small ulcers with a white or gray base and a red border inside the mouth. Canker sores can also be mildly painful and easily irritated. They are not contagious, but can return frequently and may be only one canker sore or several. Canker sores usually heal on their own within a week or two.

Aphthous stomatitis (canker sore) is diagnosed by a visual check of the mouth. A doctor or a dentist can perform this check. They look for a small depression on the soft tissue of the mouth. The center of the depression may be yellowish or white in color with a bright red surrounding edge, indicating a canker sore. There is also significant pain associated with one of these generally small sores.