Root Canal Failure: Symptoms, Reasons, and Treatment

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Root Canal Failure: Symptoms, Reasons, and Treatment

A root canal procedure is used to treat a tooth with damage within the pulp of a tooth. It’s designed to eliminate bacteria from an infected root canal and save the natural tooth. Root canal treatment is minimally invasive. Millions are performed every year with a high success rate and patients are often happy with the results.

However, all medical and dental treatments have a slight risk of failure. Learning the signs and symptoms of a failed root canal can help you get treatment and successfully save your natural tooth. Luckily, your endodontist can successfully treat your failed root canal with retreatment or surgery.

What Is a Root Canal?

A root canal is a procedure performed to repair a tooth with extensive damage or infection. The procedure is non-invasive and will relieve pain and dangers associated with infection without requiring an extraction. During a root canal, the gum area is numbed and the dentist removes the infected pulp with a drill. Once the infected pulp is completely removed, inert material is inserted into the tooth as a replacement. The tooth looks the same, but the tooth infection dangers and sensitivity are removed.

Why Do Root Canals Fail?

While many root canals are successful, some result in failure. Root canal therapy can fail for a variety of reasons. Some of these failures occur within days after the procedure while others may happen years later. These are some of the most common reasons for root canal failure.

  • Coronal seal breakdown: When your root canal is complete, the endodontist or general dentist will create a seal to protect the coronal (above the gumline) portion of the repair. If this seal is compromised, the tooth can become reinfected when bacteria and contaminants are allowed back into the tooth.
  • Crown breakdown: Sometimes a root canal requires a crown to be placed after the repair. There are two main reasons for root canal failures due to crown breakdown. If there is an extended delay between the root canal procedure and crown placement, bacteria can reenter the tooth. Additionally, a crown can suffer a crack or other damage long after the procedure is complete. This damage allows new bacteria to enter the tooth and create decay.
  • Failure to effectively clean the canal: The canal system within a tooth can be complicated, narrow, and curved. This can make accurate X-rays and thorough cleaning difficult. If a small amount of decay remains after the repair, the decay will spread and continue to damage the tooth.
  • New decay or trauma: If the tooth experiences a new injury, bacteria can reenter causing additional decay and exposing the sensitive area of the tooth to new infection.

Often, a failed root canal begins as a successful procedure. Generally, failure occurs because of damage after the procedure that allows bacteria to reenter the tooth and recreate the original situation.


Signs of Root Canal Therapy Failure

Root canal failure symptoms may be different from one person to the next. Your symptoms may be similar to the ones you originally experienced before treatment, or you may have no symptoms at all. Here are some common symptoms of root canal failure.

  • Pain
  • Sensitivity
  • Swelling
  • Discharge
  • Tooth discoloration
  • Boil or pimple on the jaw
  • Sinus problems
  • Irregularities in your routine X-ray (no physical symptoms)

Root Canal Retreatment

Treatment for a failed root canal begins with recognition of the symptoms. Whether your procedure was recent or several years ago, understanding the symptoms of deterioration can lead to saving your tooth. Seeking retreatment as soon as possible will help you avoid additional infection and eliminate pain.

The root canal retreatment procedure follows these steps.

  • A local anesthetic is applied and the tooth is reopened. If a crown is present, it must be removed.
  • The canal filling is removed.
  • The canals inside the tooth are cleaned thoroughly.
  • The canals are filled and sealed. A temporary filling is put in place immediately after the procedure to prevent reinfection. It’s important that you return to the dentist as soon as possible for a permanent crown.

Retreatment Cost

The average cost for root canal retreatment is $1,186 for anterior teeth, $1,424 for premolars, and $1,581 for molars. If you have dental insurance, it’s likely you’ll receive coverage for a portion of the treatment. Additionally, payment plans can be set up for patients who can’t pay the full price at the time of treatment.

While the cost of root canal retreatment may seem expensive, avoiding the treatment can end up costing you more. Simply extracting the tooth can seem like the most inexpensive option. However, failure to replace missing teeth can result in damage to surrounding teeth and even jaw bone loss. When possible, keeping your natural teeth is usually the best option.


Root canals are often successful and retreatment is the most common recommendation in the event of failure. However, there are other options for the treatment of a failed root canal.

Endodontic Surgery

Sometimes, traditional root canal retreatment isn’t enough to save your tooth and your dentist will recommend surgery. The most common type of endodontic surgery is an Apicoectomy (root-end resection). During surgery, the gum tissue is opened to reveal bone and remove inflamed or infected tissue. The tip end of the root is also removed. The base cost of an Apicoectomy is around $1,000 to $1,300. Additional costs like biopsies, and refilling the tooth may apply.

Extraction and Replacement

If you wish to avoid both root canal retreatment and endodontic surgery, extraction of the tooth is your final option. Though it’s generally recommended that you make every attempt to save your natural teeth, extraction may occasionally be the most appropriate option. A single tooth extraction costs from $50 to $900 depending on complications of the procedure. A dental implant to replace the tooth can cost from $1,500 to $6,000.

An untreated root canal fail is a dangerous infection that can lead to serious complications. An extremely painful abscess can result and septic infection may even occur. Infection within the pulp of your tooth cannot heal without treatment and will worsen over time. Seeking treatment as soon as symptoms occur is the best way to save your natural tooth and maintain optimum oral health.