Canker sores, also known as mouth ulcers, or aphthous stomatitis, can form on the gums, inner cheeks and lips (anywhere inside of the mouth). Canker sores, while annoying, are common, and usually heal in a week or two.
The length of time that doctor's offices need to keep records varies by state. 5 years is a common requirement. Explanations of benefits (EOB's) are sent by the insurance companies to the patient, not to the doctor's office. 4/11/13- Actually, insurance companies send EOB's to both entities, patient and doctors.
Generally hospitals keep medical records for up to seven years. They are required to keep paper records for inactive patients for no more than 10 years, but not less than 7 years. The below answer is incorrect. In the US, doctors, psychologists, psychiatrists, hospitals, and dentists must keep medical records for a minimum of 7 years.