What is the most common cause of a mouth ulcer?

Mouth ulcers, also known as aphthous ulcers or canker sores, are often caused by trauma to the mouth. This trauma can result from a variety of sources, such as accidentally biting the inside of the cheek, irritation from braces or dental appliances, or even sharp edges from food. The injury to the mucosal lining of the mouth creates an open sore that becomes painful and can lead to secondary infections.

While infections, allergic reactions, and acidic foods can contribute to the occurrence of mouth ulcers, they are not the primary cause. Infections from bacteria can cause other conditions in the mouth but are less frequently the initiating factor for typical mouth ulcers. Allergic reactions to food may lead to other symptoms such as swelling or hives rather than isolated ulcers. Likewise, acidic foods may irritate existing ulcers but are not the predominant cause behind their formation.

Understanding that trauma is the leading cause helps in both prevention and management, as avoiding practices that lead to oral injuries can reduce the incidence of mouth ulcers.