What is a Failed Root Canal?

A failed root canal procedure is one in which the dentist has failed to remove all the dead or diseased tissue from an infected tooth. Root canals are treatments for infections that affect the root or pulp of the tooth. Infections result in pain, dead tissue or even abscesses. In root canal treatment, also called endodontic treatment, the dentist cleans out the canal to remove the infected tissue. Root canal problems occur when the procedure has not fully removed the diseased tissue or when a route has been left open through which infection can return.

Getting a root canal usually eradicates the infection and saves the tooth. When a root canal procedure fails, however, it usually means that the dentist has missed an extra canal in the tooth. Some teeth are expected to have only one canal when, in some patients, those teeth actually have two. Another reason why a root canal procedure may be unsuccessful is that a tooth may have an intricate canal structure deep inside the pulp, which the dentist either misses or is unable to reach with his or her instruments.


A failed root canal can also be the result of an accident during the procedure, in which a dental instrument breaks and becomes stuck in the canal. Structural irregularities, such as curves, ledges or obstructions, can make it difficult for a dentist to completely eliminate the infected tissue. Another cause of root canal complications is when a crack develops in the root of a tooth and the canal cannot be sealed against subsequent re-infection.

One of the most obvious symptoms of a failed root canal are inflamed gums around the tooth, signifying continuing bacterial infection and decay. Other symptoms of a failed root canal include throbbing pain that gets worse, sensitivity that grows more acute, and the seepage of fluid from around the tooth. Sometimes, however, a failed root canal causes no discernible symptoms, which is why patients should seek follow-up examinations from their dentists, including x-rays.

When a patient notices symptoms of a failed root canal, he or she should seek treatment as soon as possible. One solution is for the dentist to remove the old filling material, perform a new root canal procedure and get a better seal. Another option is for an oral surgeon to perform root canal surgery, which usually involves apicoectomy, a procedure in which the surgeon cuts the tips off the roots of an infected tooth. Sometimes root amputation must be performed, where a root has to be completely removed.


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Post 3

Do dentists have legal liability if they do something wrong during a root canal and cost the patient their tooth and/or their money afterward?

I guess what I'm asking is whether a failed root canal is considered negligence? Can I sue my dentist for it?

Post 2

@ankara-- I'm not a dentist, so I may be wrong, but I think that the symptoms of a failed root canal show up fairly quickly. This is especially true if the infection is due to the dentist missing a root.

If you still have an infected root in your tooth, it should cause inflammation and pain soon after the root canal.

But it's possible to have a failed root canal for different reasons. For example, if the dentist doesn't seal the permanent crown all the way, bacteria can get in and infect the tooth. That can happen at any time, even a year after the root canal.

Post 1

How long does it usually take for a failed root canal to become apparent?

I had root canal therapy one month ago. Everything was fine afterward, at least until this week. Since the past few days, I have pain and swelling around the tooth that had root canal therapy. Does this mean that the root canal failed?

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