Like all medical procedures, there can be risks associated with root canal treatment. Patients are urged to discuss the entire procedure as well as any risks or complications before, during and after each step of the treatment.

Some people report experiencing pain during the root canal treatment. This can happen when the anesthesia fails to completely numb the nerves in and around the infected tooth. Anesthesia may also be affected by toxins released from an abscess (a pocket of pus that can form on the gums or at the roots when there is severe infection). When that pus oozes onto the gums, it can make anesthesia less effective at numbing the nerves. However, dentists are often aware of the presence of an abscess prior to the procedure and can take steps to minimize its effects on the anesthesia.

Another possible risk is that the procedure will not relieve pain or fix the problem that caused the pain. According to the Academy of General Dentistry, root canal treatments have a 5 percent failure rate. When the initial root canal therapy fails, a second treatment may be necessary. This means months or sometimes years later the entire procedure is redone, including placement of the artificial crown. Possible causes of treatment failure include:

• The original treatment failed to remove all of the infected pulp tissue and decayed tooth fragments and re-infection occurs.
  
  
• The tooth contained an additional root canal that was missed during the initial treatment, such as a narrow, curved branch of the main root canal.
  
  
• The infection spread to the tip of the tooth’s root (apex) or into the alveolar bone. Another procedure called an apicoectomy may be needed to remove the root tip.
  
  
• The adhesive or cement used to seal the root canal begins to leak.
  
  
• The weakened tooth cracks or fractures.

There are also risks associated with use of anesthesia. The injection needle used to administer local anesthetics can hit a nerve and cause extended numbness and pain. General anesthesia can cause nausea and vomiting that typically wears off within 24 hours.