Types of mouth sores include canker sores, cold sores, leukoplakia and candidiasis. They vary in their severity and causes. Mouth sores could be the symptom of a disease or disorder; infection from bacteria, viruses or fungus or result from irritation caused by braces, dentures or the sharp edge of a broken tooth or filling. Your dentist should examine any mouth sore that lasts a week or longer.
Above article from: MouthHealthy.org