Root Canal Re-treatment

Root canal re-treatment is indicated if the root canal treated tooth shows symptoms of infection or inflammation.

Reasons for failure of Root Canal Treatment

Root canal treatment has a success rate of over 90 percent. In some instances, root canal treatment fails and re-treatment is necessary. Some of the more common causes of root canal failures include:

  • Poor fill of the root canals. If the filling material is not condensed properly and voids are left in the canal, there is a potential for root canal treatment failure. This can occur due to bacteria and bacterial toxins being able to penetrate through the tooth and into the surrounding bone area. This can lead to localized inflammation, pain on chewing and ultimately an infection.
  • Coronal leakage is another reason for root canal treatment failure. Bacteria can re-infect the internal portion of the tooth, which eventually can lead to inflammation or infection of the tissues supporting the tooth. This can occur if the tooth is not restored with a crown in a timely manner.
  • Short root canal fill, is an instance where the filling material does not extend to the desired length. This can occur when a canal of a tooth is closed and inaccessible, complex root canal anatomy and extreme curve of the tooth root. Short fill does not necessarily mean that the treatment will fail.
  • Long root canal fill. In this case the filling material is not contained in the root of the tooth and makes it out of the tooth. The body will absorb any sealant material that makes it out of the root into the surrounding bone. If the actual filling material makes it out of the tooth, it can cause chronic irritation and inflammation of the supporting structures of the tooth. In some instances this can lead to long-term discomfort on chewing. Overfill does not usually lead to an infection just long-term inflammation.
  • Fracture of the crown of the tooth. If the tooth is not restored shortly after the root canal is completed there is always a risk of tooth fracture. Depending upon where the fracture occurs, in some instances the tooth can be saved. If the fracture occurs below the gum line the tooth can potentially still be saved with crown lengthening surgery (gum surgery). This leads to extra dental visits and costs.

Root Canal Re-treatment Explained

The purpose of the root canal re-treatment is to eliminate any bacteria that were left, or somehow made it back into the canal or canals of the tooth. Another important objective of the re-treatment is to obtain a superior seal near the tip of the root. The third and most important objective for the patient is to eliminate any symptoms of infection or inflammation such as pain on chewing or pain in and around the tooth.
If previous root canal treatment fails and it is determined that root canal re-treatment can improve on the original treatment, the re-treatment would be indicated. If patients wait too long to have the root canal treated tooth restored and the temporary filling fails, bacteria can end up back in the inner portion of the root. In that case root canal re-treatment would be indicated as well.

Root canal re-treatment can be done under local anesthesia for the comfort of the patient. Even if anesthesia is not used the patient should not feel anything during the procedure because all the nerve tissue was extracted from the tooth at the original treatment. Similar to the original treatment, an opening is made on the biting surface of the tooth. The old filling material is removed with solvents and heated instruments. After removal the canal is cleansed and disinfected in an attempt to eliminate any bacteria and bacterial byproducts. After a thorough irrigation of the tooth the canals in the roots are refilled with special filling material. As with the initial root canal treatment a temporary filling is placed. If the tooth was symptomatic before the procedure the symptoms should subside within 3-4 days or as indicated by your dentist. Before the final restoration is placed, the tooth should be completely symptom free. Make sure you inform your dentist if symptoms persist, before the final restoration is placed.