As occasionally happens with any dental or medical procedure, a tooth may not heal as expected after initial treatment for a variety of reasons:
- Narrow or curved canals were not treated during the initial procedure.
- Complicated canal anatomy went undetected in the first procedure.
- The placement of the crown or other restoration was delayed following the endodontic treatment.
- The restoration did not prevent salivary contamination to the inside of the tooth.
- New decay can expose the root canal filling material to bacteria, causing a new infection in the tooth.
- A loose, cracked or broken crown or filling can expose the tooth to new infection.
- A tooth sustains a fracture.