In rare cases, root canal therapy fails to work as expected. The treated tooth might not heal properly or a patient might experience post-surgical complications that jeopardize the tooth. Root canal retreatment involves the removal of the previous crown and packing material, the cleansing of the root canals, and the re-packing and re-crowning of the tooth. In short, root canal retreatment is almost identical to the original procedure, aside from the structural removal. The success rate for a root canal retreatment runs at around 75%.

Why is root canal retreatment required?

Though the prospect of more endodontic surgery might not be pleasant, root canal retreatment is usually completed in 1-3 visits.

There are a number of reasons why root canal therapy unexpectedly fails, including:

• Cracked crown leaking filling material.
• Curved or narrow canals not treated during the original procedure.
• Delay in the placement of restorative devices following the procedure.
• New decay to the tooth.
• New fracture in the treated tooth.
• Saliva entering the restorative structure.
• Undetected complex canal structures.

What does root canal retreatment involve?

On the day of the retreatment procedure a local anesthetic will be administered, and the affected tooth is isolated with a rubber dam. The amount the dentist can do within a single appointment will much depend on the amount of inflammation present, and the complexity of the treatment.

The first step in a root canal retreatment is to gain access to the inner tooth. If a crown and post have been placed, these will be removed.

Next, filling material and obstructions that block the root canals will be removed. This removal is conducted using an ultrasonic handpiece. The advantage of using this tool is that any unwanted material is vibrated loose. Tiny instruments will then be used to clean and reshape the root canals. X-rays may be taken to ensure that the roots are thoroughly clean. If this part of the treatment proves to be complex, medicated packing material will be applied, and the rest of the cleansing procedure will be done at the next visit.

When the dentist is confident that the root canals are completely clean, gutta-percha is used to pack the space. This rubbery material seals the canals to prevent bacterial invasion. Finally, a temporary crown or filling is applied to tooth. At a later date, the permanent crown will be placed.

If you have any questions or concerns about root canal retreatment, please ask your dentist.