Why are my gums sore after getting a filling?

Sore gums after fill: This depends on how deep and the location of the filling? It also depends if a rubber dam was used also. Usually, the gums maybe sore if they were abraided during polishing, or if an injection was given that area to gain profound anesthesia. It should be for a short duration and should go away in 2 to 24 hours.

Depends: If the cavity extended near-to or below the gums, removing all of the decay and then polishing the filling material can cause temporary irritation to the gums...This should subside within a few days after the filling appointment. If your irritation lasts longer than this, see your dentist to make sure it isn't something else causing your symptoms.