If the ulcer is initiated from a sharp teeth or denture or fractured crown then place some cotton or chewing gum on the sharp edge to stop further irritation until you see a dentist.

Mouth sores generally last 7 to 10 days, even if you do not do anything. They sometimes last up to two weeks. There are several measures you can take, however, to feel better during that time :
	1.	Gargle with cool water or eat soft diet. This is particularly helpful if you have a mouth burn
	2.	Avoid hot beverages and foods, spicy and salty foods, and citrus.
	3.	Take pain relievers like Paracetamol.
For cancer sores, it is helpful to also :
	1.	Rinse with salt water..
	2.	Orabase, a nonprescription preparation, may be applied for protection inside the lip and on the gums. Blistex or Compho-Phenique may provide some relief of cancer sores and fever blisters, especially if applied when the sore initially appears.