One of the most commonly occurring lesions in the oral cavity is a mouth ulcer. While mouth sores can be annoying, uncomfortable and unsightly, they are often harmless, and will resolve within a few days without requiring any medical treatment. However, when these lesions do not get better after a couple of weeks, frequently recur, or if new symptoms begin to appear, it is important to get a more comprehensive evaluation by a dentist or other qualified healthcare provider.

While often the result of an actual injury like biting the cheek or the irritation of a sharp orthodontic wire, a mouth ulcer can also be caused by certain drugs, chemical sensitivity, diseases, or as a side effect of medical treatment like chemotherapy. A mouth ulcer such as a canker sore, which is also known as an aphthous ulcer, may even be triggered by stress and anxiety or hormonal changes.