Q What causes canker sores in the mouth?
Canker sore are small shallow ulcers that appear in the mouth and often make eating and talking uncomfortable. There are two types of canker sores: simple and complex. The exact cause of most canker sores is unknown stress, or tissue injury is thought to be the cause of simple canker sores. Certain foods -- including citrus or acidic can trigger a canker sore or make the problem worse. Sometimes a sharp tooth surface or dental appliance, such as braces, or ill-fitting dentures, nutritional problems, such as vitamin B-12, zinc, folic acid, iron deficiency, coeliac disease, gastrointestinal disease can cause canker sores. Canker sores might result from viruses or bacterial infection. Those experiencing chemotherapy also have a high risk for these mouth ulcers. Serious viruses like HIV can cause very long-lasting and painful canker sores.