Ulcers are painful sores that appear inside the mouth. They are usually red or yellow.
They are different from cold sores, which appear on the outer lips and are caused by a virus.
Usually a single mouth ulcer is due to damage caused by biting the cheek or tongue, or by sharp teeth, brushing or poorly fitting dentures.
These ulcers are called ‘traumatic' ulcers.
If you have a number of mouth ulcers, and they keep coming back, this is called ‘recurrent aphthous stomatitis'.
► See also: ORAL PATHOLOGY: Pathological abrasion of dental hard tissues
Traumatic ulcers are usually on their own, are next to the cause of the damage and go away once the source of the problem is removed.
Fuente: Youtube Bupa Health UK