Molar 50% filled amalgam replaced with white filling returned to dentist ,sensitivity for 1 month dentist xray no problem with nerve, periodontitis?

Not a Perio problem: May have residual problem with the tooth. It originally had a large filling and the nerve of the tooth may have been affected. May take time to subside. Tooth (filling) may need a very minor adjustment if over-contoured. Nerve of tooth may be becoming devitalized and root canal treatment may be necessary. Toth may be fractured. Reevaluate with your Dentist or an Endodontists, root canal specialist