When you go into the dentist for a filling or other dental procedure that requires anesthesia you can feel numb for up to 3 hours after you've been given the anesthesia.
So it's normal to still feel numb for up to 3 hours after you get the filling put in which is usually enough time for the anesthesia and numbness to wear off.
Just take it easy for the first 3 hours after the filling is put in and then you should be feeling better and the numbness should be gone.