How long does cavity filling numbness last?

It usually only lasts up to a few hours. It's a temporary numbing so that the person doesn't feel pain during the cavity filling.

It really depends on how much they used. when I get my teeth done I usually have to get two shots so It doubles the time it lasts for me. But on a normal person on average it goes away after 2-3 hours and you should start getting feeling back in about 1-2 hours.