Two root can treated teeth showing signs of treatment failure.

A root canal treatment can fail. 

Sometimes the tooth does not heal completely due to one or several causes. In these circumstances, the tooth in question will either need retreatment of the initial treatment that was performed or in severe circumstances when a tooth is really not salvageable, an extraction.

Why would you consider doing a retreatment of a previously root treated tooth?

To re-treat is a better alternative to extracting a tooth.  If a tooth presents  enough tooth structure to be restored and the surrounding bone and gum still give enough support, the tooth stands a very good chance to be saved.

Retreatment, if done according to the recommended protocol, has a success rate of 78%.  A root canal retreatment can be far less expensive than the alternative that will include an extraction and replacement with a dental implant or bridge work.  Aesthetically pleasing and functional prosthetic teeth cost much more than repairing and maintaining one’s natural teeth.

What would cause the initial root canal treatment to fail?

There are multiple causes for root treatments to fail, but to explain a few:

  • If you have a prosthetic crown on your root canal treated tooth that was placed a long time ago, there can be a chance that the crown might not be sealing properly.  When the connection between the crown and tooth structure is not sealing off completely, leakage can occur, leading to secondary decay to infiltrate the tooth structure.  Your dentist will explain that it appears that your crown is “leaking”.  Coronal leakage is a major cause of root canal failure. 
  • Root canal treated teeth that are only repaired with a composite filling, especially back molar teeth, stand the chance of breaking due to the strong forces inflicted on these teeth.  When filling material breaks and the root canal material is exposed to the oral environment, which includes bacteria and saliva, the root gets contaminated, and infection in the canals can occur.
  • It can happen that the dentist wasn’t able to allocate and treat one or more canals during the initial treatment or that a canal wasn’t clean all the way to the root apex. That causes bacteria to stay behind in the tooth structure and causes the remaining filled canals to become contaminated, leading to root canal failure.
  • When a root treated tooth becomes decayed, reinfection can occur.
  • Tooth or root fracture after root canal treatment was performed does occur due to an already compromised structure and can often be the cause of treatment failure.

What to expect when you need retreatment?

A retreatment, depending on the signs and symptoms of the tooth, will either be performed during 1 to 5 appointments.  The amount of work that can be done in a single appointment depends on the severity of the present infection and inflammation as well as the complexity of the treatment needed.

On the day of retreatment, local anaesthetic will be administrated.  The affected tooth will be isolated with a rubber dam, keeping the patient’s airway protected, the working area dry and free from contamination.  An access must be made through the existing filling or crown to access the root canal isolation material.  Sometimes the prosthetic crown will be removed completely if the dentist suspects that the crown is leaking.  If the primary filling or crown was supported by a post – a fibre or metal pin cemented into one or more roots to give coronal support – the post will have to be removed next.

The isolation material that was placed inside the roots to seal the canals will now be removed. Specific instruments will be used to clean and shape the root canals. X-rays are taken to ensure that the filling material has been removed, and the canals will again be disinfected. Once all material has been removed, the canals will be packed with a medicated dressing and closed temporarily to give the tooth and surrounding tissue time to start the healing process. 

During the following visit, the canals will again be disinfected, and the canals will be refilled with a cement and sealing material (Gutta-Percha). The canals are being sealed off to prevent bacterial infiltration.

Finally, a new filling will be applied to the tooth, or a new crown will be placed.

Retreatments at Enamel Clinic

If you require a retreatment or have an existing root treated tooth that causes problems, do not hesitate to contact us for your endodontic consultation.

We make use of state of the art equipment and technology to ensure that your retreatment is done in line with the highest world standards. Microscopic dentistry is part of our standard protocol. 3D CBCT scans taken before initiating a retreatment is standard practice. We also use laser technology to form part of our canal disinfection protocol to ensure that your retreatment is successful. 

We take pride in our work and take care of our patients. That is why we apply the principles of slow dentistry to ensure, as far as we can, a successful outcome.

Written by: Dr Sonja Britz