Approximately 20% of the population suffers from canker sores. Canker sores do not appear to be caused by viruses or bacteria. The cause is unknown. It is theorized that there is a hereditary immune system link. This means that the body's defense mechanism (your immune system) is triggered and attacks your normal cells and tissue in error. There are also numerous local factors which are thought to increase ones susceptibility to mouth ulcers.
Mouth trauma such as following a dental procedure, cheek, tongue or lip biting, even aggressive tooth cleaning can cause canker sores. With an immune system link, anything that would lower ones resistance may trigger a canker sore outbreak. This may occur with stress, any illnesses especially viral infections (flu, cold), dietary deficiency (iron, folic acid or vitamin B12), hormonal changes during menstrual periods and possible food allergies. Most women experience improvement or remission during pregnancy and research has shown that hormone replacement therapy has been used successfully to treat women. It is also theorized there may be an allergic reaction to a type of oral bacteria. Some studies have shown a link to those who have also have gastrointestinal problems. Canker sores may also occur with no identifiable cause.
Q: How do I know if my ulcers are canker sores?
Canker sores are diagnosed by the appearance and location of the ulcers (see causes). We highly recommend that you verify the diagnosis with your dentist or doctor, especially if the ulcer (s) persists or recurs.
Other causes of oral ulceration are herpes and other autoimmune conditions (pemphigoid, erythema multiforme, pemphigus, lichen planus) and more rarely oral cancer (carcinoma). A relatively new ulcer-like condition is hairy leukoplakia, a condition that occurs with AIDS and one that may be mistaken for the common canker sore. You must consult with a Doctor to confirm a diagnosis. The only definitive diagnosis is to have a biopsy of the ulcerated area.