Occasionally a tooth that has undergone endodontic treatment fails to heal or pain continues despite therapy. Although rare, sometimes a tooth initially responds to endodontic therapy but becomes painful or infected months or years later. When either of these situations occur, the tooth often can be maintained with a second endodontic treatment. Root canal retreatment is typically completed in two appointments in our office, but the number of visits depends on your particular case. Retreating a tooth that has already had endodontic treatment is frequently more difficult than initial root canal treatments. Root canal filling materials need to be removed as well as any material placed in the canals for support such as posts. Previously root canal treated teeth often have obstructions that may need to be overcome to completely clean the root canal system. These obstructions include ledges, calcifications, separated instruments or difficult to remove filling materials. Spreading the treatment over two appointments gives Dr. Baur additional time to properly treat the tooth while keeping the patient comfortable. Equally important, at the first appointment Dr. Baur places a medicated paste in the roots of the tooth that actively disinfects the tooth even when the patient is not in the chair. Occasionally this medication may need to be replaced over multiple visits to adequately control the infection or inflammation associated with a tooth.