Mouth Still Numb After Crown-Fitting

[Rob]

Hi, I have been through a long road getting my crowns finally put on, it has taken multiple visits, and several trips, but I finally have my new crowns on, and they look wonderful. However, due to the fact that my canines were extremely sensitive, the dentist injected me several times with numbing medicine at my request during the procedure..Usually, it wears off in a few hours, but this last time, on my right side, the upper part of my face where the needle went in, just below my eye and over part of my cheek is still numb..It's been three days since my visit. Should I be concerned about this, what could be the reason it's still numb? Do I need to give it more time, what is the cause of it still being numb? Thanks