Pain in already Root canal treated tooth can be due to multiple reasons. Most commonly it is either failed previous RCT, recurring dental decay, or fracture of the tooth.
Next Steps
Visit a dentist and first determine the cause of the treatment.
if pain is due to either failed RCT or decay it can be retreated followed by cap.
if it is due to fracture of the tooth we will have to extract the tooth.
Health Tips
if the pain occurs while you release your bite it is mostly due to fracture tooth.