Occasionally a tooth that has had root canal treatment may require re-treatment, endodontic surgery, or tooth extraction. Root canal Re-treatment is undertaken when the previous root canal treatment has failed or is deemed to be suboptimal. Reasons for failure of initial root canal treatment commonly include: Difficulty incurred during initial treatment, re-infection from a leaky filling or decay, presence of cracks / fractures or presence of a cyst around the root end.
Sometimes re-treatment is performed to improve the technical quality of the root canal filling prior to the placement of a new crown or bridge, rather than to eliminate residual infection.
Success of the treatment may be influenced by the quality of the new filling or crown. If there is not enough tooth structure left, extraction of the tooth may be necessary. In this case, you will be referred back to your own dentist for further treatment.
Teeth that have had previous root canal treatment may have additional problems such as presence of broken instruments or blocked canals, which make preparation and cleaning of the canals more difficult. If this makes it impossible to achieve a certain standard of root canal treatment, the chances of success of the treatment may be reduced, in which case, extraction may be advised.