Root Canal Treatments - Outcome and Complications

Authored by Dr Ben Williams, 09 Jul 2017

Reviewed by:
Dr Hayley Willacy, 09 Jul 2017

The success of RCT can only be judged over time. Dental abscesses and pain on biting will often resolve after RCT but they will return if the root canal was not cleaned or sealed properly. To monitor healing, a review X-ray should be taken one year after an RCT is completed.

  1. If the tooth is symptom-free and the X-ray shows signs of bone healing around the root apex, this indicates that the RCT may be successful. A further review X-ray after 3 to 5 years is advisable.
  2. If the review X-ray shows evidence of ongoing bone destruction around the root apex, the RCT has failed. The tooth may be painful to bite on to (or it might be symptom-free) and there may be evidence of soft tissue infection in the form of an abscess or draining sinus on the gum. The main treatment options for a failed RCT include re-RCT, tooth extraction or possibly apicectomy.
  3. If the X-ray shows neither sign of healing nor increased damage to the bone at the root apex and the tooth is symptom-free, it is usually acceptable to monitor the tooth with X-rays intermittently for several years. Evidence of further bone damage or infection should be treated as for a failed RCT.

Studies indicate that approximately 90% to 95% of teeth that have undergone their first RCT will still be present after five years. Your dentist will discuss any factors that may affect the success of your RCT with you.

Complications and causes of RCT failure are outlined below.

  • Perforation: when cleaning and shaping the root canals, your dentist might accidentally pass the drill or endodontic files through the floor of the pulp chamber or the side of the root into the bone. Depending on the size and location of the hole it may be possible to repair it, otherwise it will be necessary to extract the tooth.
  • Fractured instrument: RCT files can occasionally fracture inside the root canal. If it is not possible to remove the broken piece then the chances of achieving a successful RCT can be significantly reduced. However, if the canal was disinfected properly prior to the fracture and the fragment of instrument was located in a favourable position within the root canal it may be possible for the RCT to be completed and successful.
  • Root filling material too long or short: an ideal root filling should fill the canal right up to the tip of the root. If the filling material is pushed through the root apex, out into the bone then the bone may become irritated and fail to heal properly. If the root filling material is not packed tightly or does not fill the canal properly then bacteria will multiply in the spaces and continue to infect the bone.
  • Disinfectant passed through root apex: the cleaning solution used to disinfect the root canal should only be used within the root canal. If it is accidentally squirted through the root apex into the bone it can cause severe inflammation, pain and damage to the bone and soft tissues.
  • Leaking restoration: on completion of RCT it is vital to have an effective tooth filling or crown to seal off the root filling. If this is not achieved then decay, food and bacterial leakage will cause the root filling to fail.
  • Tooth fracture: one function of the pulp is to detect biting forces and prevent tooth fractures caused by biting too hard. Thus back teeth that have been root filled or are midway through RCT are more vulnerable to fracturing than those with healthy pulps. Your dentist will advise you to have a soft diet until your RCT has been completed and a suitable crown or filling has been placed to reduce the risk of tooth fracture.

Your dentist will assess your tooth and warn you of any possible complications before starting treatment. For example, if you have very curved roots you should be told that the risk of perforation is higher than if the tooth had straight roots. If your tooth has features which indicate that the procedure might be too challenging or if your dentist encounters one of the complications outlined above, they may refer you to an RCT specialist. They are also called endodontists.

Further reading and references

I'm 35 and had 5 wisdom teeth out 8 days ago (yes I had an extra one) under a general anesthetic. I never had very much pain from the actual extraction areas, just what was to be expected. But ever...

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