We're sure that at least once in your life, you've experienced a canker sore (ulcer). While they aren't any of an issue to your health, they can be extremely annoying, as they can leave you in a state of immense pain while eating or even moving your mouth. Fortunately, though, they don't last forever. After a few days, they tend to disappear on their own, as if they were never there. However, it does help to know how to get rid of them faster to shorten the ordeal you have to go through. To do that, though, you need to know how they show up in the first place.