What is endodontic retreatment? 

Occasionally a tooth that has undergone endodontic treatment fails to heal or pain continues, despite therapy. Although rare, sometimes a tooth initially responds to root canal therapy but becomes painful or diseased months or years later. When either of these situations occur, the tooth often can be maintained with a second endodontic treatment.

Steps: 

1. Accessing the previously treated area by making a small opening in the tooth.  

2. The contents of the nerve tunnels are cleaned out.  The contents could be filling material, necrotic tissue, and bacteria.  

3. Finally, a rubber filling material called Gutta Percha is placed inside the tunnels to seal them. 

Click on the following link to watch a video about root canal retreatment: https://www.youtube.com/watch?v=PHxlvvo0-Po