what causes sores in your mouth
There are many types and causes of mouth sores. Mouth sores may be caused by an infection, a bodywide (systemic) disease, a physical or chemical irritant, or an allergic reaction (see Table: Some Causes of Mouth Sores). Often the cause is unknown.
Mouth sores may be caused by irritation from: 1  A sharp or broken tooth or poorly fitting dentures. 2  Biting your cheek, tongue, or lip. 3  Burning your mouth from hot food or drinks. 4  Braces. Chewing tobacco.
Canker sores are thought to be caused by: 1  Injuries to the mouth, as seen frequently by contact sports players. 2  Temperature hot food or drink may cause a canker sore in the area of the mouth that was essentially burnt by the offending substance.
Poor-fitting, complete or partial dentures may cause canker sores in the area of the mouth where the denture may rubbing on the tissue. The development of a canker sore is often one of the first signs that indicate the need for a denture adjustment by your dentist or denturist.