What is the best way to get rid of a mouth ulcer?

It depends.: Many mouth ulcers are really caused by a latent viral infection that never really goes away. The ulcers flare up at times when your immune system is already weak, like at times of high stress, poor sleep, the same time as a cold, etc. There is really no definitive cure and most viral related ulcers go away on their own within 7-10 days. Topical antiviral creams can shorten that time.

Lasers: The problem is once you get an ulcer it takes time to heal. The laser can promote quicker healing and eliminate pain.