Root Canal Complications - Failed Root Canal
Root Canal Therapy

Root Canal Complications - Failure Rate

Root canal treatment is a procedure with a high success rate of more than 95%. Unfortunately, in a 5% of cases root canal complications result in a failed root canal.

The success of root canal therapy depends on a number of different factors and the likelihood of failure can vary considerably from case to case. It is important to discuss the prospects of the treatment with your dentist before having root canal therapy. However, some of the root canal complications are not predictable.

Root canal complications may increase significantly the cost of the overall treatment. A good dental insurance may prove very useful in this case.

Symptoms of failed root canal

If after the endodontic treatment, the inside of the tooth or the tissues surrounding the root remain infected, the procedure is considered failed. The usual symptoms of failed root canal treatment include tooth pain and tenderness or swelling of the gums in the area near the tooth.

In other cases, problems such as a new infection can develop without any symptoms. Follow up examinations and x-rays are very important in determining the success of a root canal treatment. X-rays will help the dentist to detect any sign of inflammation in or around the tooth that could indicate root canal complications. Root canal complications may appear immediately following the endodontic treatment, or even after many years.

Causes of Root Canal Complications

There are many conditions that may cause root canal complications, resulting in a failed root canal. These conditions include :

  • Missed root canals. A root canal or part of it may be missed or a canal may not be cleaned out or sealed to its full length.
    • A tooth may have more root canals than it is normally anticipated. A dentist may not look for or notice this extra canal allowing the infected pulp in it to recontaminate the tooth.
    • The root canal system of some teeth is complicated with branches extending to the sides of the canal. Branches, especially in curved canals, are very difficult to detect. A hidden root canal branch will remain infected causing the treatment to fail.
    • In some cases even if the branch is noticed by the dentist, it may be in a position difficult to reach with the endodontic files. That is usually the case with horizontal branches.
    • If the dentist does not measure correctly the length of the root canal, the endodontic file and the filling material will not reach to the end of the root, leaving infected tissue behind. Sooner or later, this will result in a new tooth abscess.
  • Crack in the root of the tooth. An existing small crack at the root of the tooth that remains undetected will allow bacteria to re-enter and re-infect the tooth.
  • Vertical root fracture. When the pulp dies, teeth tend to become brittle. A serious root canal complication is the fracture of the root of the tooth during the filing procedure. Endodontic surgery is needed to remove the fractured root and save the tooth but the odds are against it.
  • Root perforation. Another usual problem is when an endodontic instrument accidentally perforates the root. A missed curve in a root canal may result in the endodontic file penetrating the side of the tooth. If the opening is not sealed it will be a gate for the bacteria to re-enter the tooth.
  • Endodontic file fracture. The most common root canal complication is caused by the accidental breaking, inside the canal, of the endodontic files which are used to clean and shape it. If the breaking of the file happens during the shaping of the canal after it is cleaned, it is possible to fill and seal the tooth even without removing the fragment. But if the root canal is not yet cleaned, the broken file has to be removed. If the dentist is unable to remove it, the only solution is an endodontic surgery procedure, called apicoectomy.

Other root canal complications :

  • A tooth that has had endodontic therapy can develop a new root canal infection and/or abscess. Sometimes during an endodontic procedure, bacteria may get pushed out through the tips of the roots into surrounding tissues. The surrounding tissue will become inflamed and possibly infected, developing an abscess.
  • Defective dental restoration. If the tooth is not properly restored or the materials used are not of good quality, bacteria may be allowed to pass through the restoration (filling or crown) into the interior of the tooth and cause a new root canal infection.
  • Extensive damage / fracture. A dentist will sometimes begin a root canal even when the prognosis is poor, due to the extensive tooth decay damage, in a last attempt to save the tooth. If during the procedure, the dentist decides that the tooth can not be saved, he will abandon the root canal treatment and extract the tooth. Sometimes the tooth may fracture during or after the procedure and also need to be extracted.
  • Delay in obtaining a final restoration (crown) may result in fracture and/or possible loss of the tooth.

Treatment options after failed root canal procedures

Root canal complications can cause a failed root canal, but the tooth has usually a second chance. If the treatment has failed, the dentist will evaluate the condition of the tooth and the reasons of the root canal complications, in order to decide if the tooth can be saved. Unfortunately, in some cases the tooth can not be saved and it has to be extracted. A bridge, implant or a partial denture has to replace the lost tooth.

There are three options available after a failed root canal :

  • The first option for solving the problems of a failed root canal is the root canal re-treatment. The procedure is similar to the regular treatment but much more difficult. Rarely general dentists will perform the root canal re-treatment themselves, usually they refer the patient to a specialist endodontist.
  • Depending on the nature of the problem, the endodontist may decide that endodontic surgery must be performed in order to save the tooth. The procedure is called apicoectomy and it involves the surgical removal of the root’s tip (apex). A small filling (retrofill) is then used to seal the root.
  • The chances for a successful treatment of a failed root canal are between 50% and 75%. In some cases, despite root canal retreatment or endodontic surgery, tooth extraction must be performed. The lost tooth is recommended to be replaced as soon as possible to prevent more teeth problems. The best solution for tooth replacement after extraction is to replace the lost tooth with a dental implant.

The additional treatment cost involved with root canal complications is significant and many patients may not afford it if they are not covered by their dental insurance. Learn how to choose a dental insurance plan that will help you provide the best dental treatment to yourself and your family.

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