So if you have to have a cavity filled or already did you may have started to wonder how long it will take for the numbing to go away. Drooling and sagging mouths are typical symptoms of having a cavity filled so you can imaging why people would want this to go away as quickly as possible. Well the answer is not as simple as it may sound. Numbing goes away based on a few different things. I would consult with a dentist if you would like to get a more detailed analysis of what to expect but this article should give you a generally good idea of what to expect.