Tooth sensitive to cold after 4-5 months after filling, what to do?

Go back: Go back to your dentist to have that tooth evaluated. There are a number of things that can be done in such cases. It might require refilling the tooth with another type of filling and a sedative base. There are other options and your dentist will go over them with you.

See your dentist: Sensitivity to cold is a sign that the tooth is alive but not very happy. It could be many things. There might be something wrong with the filling or your tooth. Check with your dentist ASAP.

Many possibilities: If your tooth was not sensitive before the filling and has been sensitive since the filling, there could be a problem with the filling which should be rechecked by your dentist. If the cavity was deep the pulp or nerve may be irritated. This may lead to a root canal if the condition worsens. Either way after 4-5 months this should be rechecked by your dentist.