Mouth Ulcer Causes There are different types of mouth ulcers. Ulceration can be caused by physical or chemical trauma.
Aphthous ulcers are usually small and creamy-white.
They are sometimes associated with stress and may come in crops during a particular anxious time, such as starting school. They are usually recurrent. A traumatic ulcer is larger and usually starts as a sore patch on the inside of the cheeks, possibly after injury or by the biting or rubbing of a rough tooth. It enlarges to form a painful yellow crater. It heals very slowly and takes 10-14 days to clear completely.