Occasionally, a tooth that has undergone endodontic treatment fails to heal or pain continues despite therapy. Sometimes a tooth may initially respond to root canal therapy but become painful or diseased months or years later. New trauma, deep decay, or a loose, cracked or broken filling can also cause new infection in your tooth. When any of these situations occur, the tooth often can be maintained with a second endodontic treatment, or retreatment. In some cases, the endodontist may discover additional, very narrow or curved canals that could not be treated during the initial procedure. Advances in technology are constantly changing the way root canal treatment is performed, so your endodontist may use new techniques that were not available when you had your first procedure.
During retreatment, the endodontist will reopen your tooth to gain access to the root canal filling material. In many cases, complex restorative materials - crown, post and core material - must be disassembled and removed to permit access to the root canals. After removing the canal filling, the endodontist can clean the canals and carefully examine the inside of your tooth using magnification and illumination, searching for any additional canals or unusual anatomy that requires treatment. After your endodontist completes retreatment, you will need to return to your dentist to have a new crown or other restoration placed on the tooth to protect and restore it to its full function.
Most teeth can be retreated. Occasionally, a tooth cannot be saved, though, because the root canals are not accessible, the root has a pre-existing fracture, the tooth doesn't have adequate bone support, or the tooth cannot be restored. However, advances in endodontics are making it possible to save teeth that even a few years ago would have been lost. When endodontic retreatment is not effective, endodontic surgery may be able to save the tooth.