what do canker sores come from
Some possible causes of canker sores include the following: 1  Injury to the mouth may cause simple canker sores. 2  Injury could be from vigorous tooth brushing, dental work, braces or dentures, or a sports accident. 3  Acidic foods, including citrus fruits, may trigger a canker sore or make it worse.ome possible causes of canker sores include the following: 1  Injury to the mouth may cause simple canker sores. 2  Injury could be from vigorous tooth brushing, dental work, braces or dentures, or a sports accident. 3  Acidic foods, including citrus fruits, may trigger a canker sore or make it worse.