How do you know if you have an open cut in your mouth?

Cut in mouth: Rinse with some listerine or scope and that cut will burn! however, because the mouth is so vascular, cuts heal very quicklyf.

Bleeding?: If you had a sharp object capable of cutting the tissue and it bleeds, you may have cut your mouth. You could also have reopened an old wound; abraded a blister, ulcer or other lesion; or have gum disease. See your dentist for sure. A traumatic injury will heal rapidly, pathology won't.

Take a look: Sometimes you can see it, sometimes you will feel it, and most of the time it will hurt. It can bleed, too. But these wounds heal rather quickly. Feel better soon.