Hi.. there is possibility of reinfection in root canal treated tooth. Source of infection could be either periapical or periodontal. A good doctor should try to solve first by doing re- root canal by giving good dressing with metapex followed by obturation if infection disappears. Sometimes even after doing this prognosis will be poor and tooth might require surgery or in worst case extraction. Visit a endodontist for best treatment. Regards

Yes of course a re root canal treatment can be done.. only that a medicament have to be placed inside the canals before obturation(filling of canals),to heal the existing infection.