With proper care, most teeth that have had endodontic (root canal) treatment can last as long as other natural teeth. Root canals performed by endodontists (root canal specialists) have a 95% success rate. In some cases, however, a tooth that has received endodontic treatment fails to heal. Occasionally, the tooth becomes painful or diseased months or even years after successful treatment.

Why do I need retreatment?

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.
In other cases, a new problem can jeopardize a tooth that was successfully treated.

For example:

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 a new infection. A tooth sustains a fracture. Retreatment is performed in two visits and involves the following:

• At the initial visit the endodontist will examine the tooth, take x-rays and discuss your treatment options. If you and your endodontist choose retreatment, the retreatment will be scheduled at that time for a future date.
• At the retreatment appointment the endodontist will administer local anesthetic to numb the tooth. After the tooth is numb, the endodontist will reopen your tooth to gain access to the root canal filling material. In many cases, complex restorative materials (crown, post and core material) must be disassembled and removed to permit access to the root canals.
• After removing the canal filling, the endodontist can clean the canals and carefully examine the inside of your tooth using a microscope, searching for any additional canals or unusual anatomy that requires treatment.
• After cleaning the canals, the endodontist will fill and seal the canals and place a temporary filling in the tooth. Post space may also be prepared at this time.
• After your endodontist completes retreatment, you will need to return to your dentist as soon as possible to have a new crown or other restoration placed on the tooth to protect and restore it to full function.
• If the canals are unusually narrow or blocked, your endodontist may recommend endodontic surgery.