All About Mouth Ulcers
Mouth ulcers, as opposed to cold sores, are open wounds that are found in the mouth. Ulcers are commonly caused by the accidental biting of the cheek or tongue, ill-fitting dentures that rub against the gum, or chipped teeth or fillings that cut the cheeks or tongue.
Mouth ulcers often heal by themselves but if one lasts for more than three weeks, it is best to consult your dentist.
This Q&A by the British Dental Health Foundation offers a quick guide on everything you need to know about mouth ulcers and the most important—what to do when you have one.
http://www.dentalhealth.org/tell-me-about/topic/mouth-cancer/mouth-ulcers