Failed Root Canal – All About Failed Root Canal Management

A root canal is an invasive dental treatment that aims to remove the infected or inflamed pulp tissue. Moreover, it prevents the spread of disease into the surrounding bone, which often leads to loss of tooth at an early stage. Root canal procedures are typically carried out in a dental office under local anesthesia. Although root canal treatments have a 95% success rate, there may be few cases where the root canal treatment may fail.

A failed root canal can be caused by several reasons such as improper cleaning of the root canals, improper sealing of the canal orifice, missed accessory root canals, crack in the tooth root, and overextension of the filling material.


It is essential to identify the symptoms of a failed root canal at an early stage. Some of the common symptoms of a failed root canal may include pain in the treated tooth, swelling around the tooth root, tenderness, and discomfort on chewing food.

Typically, failed root canals require retreatment. However, in severe cases, the tooth can also go for extraction. The dentist decides treated a failed root canal after evaluating the dental condition and extent of infection. Today’s article will highlight the causes and management of failed root canal.

What causes a failed root canal?

Usually, root canal failures occur when there is a deficiency associated with two main steps of a root canal treatment. The first is the cleaning and shaping the root canal, and the second is creating a proper seal post-treatment. Some of the common reasons for root canal failure as given below –

  • Missed root canals, especially in teeth that tend to have more than one root canal in each tooth root.
  • Unfilled accessory root canal (1)
  • Unfilled lateral canal
  • Fracture of the tooth root
  • Under filled root canal
  • Overextension of the tooth filling
  • Inadequate seal post-treatment
  • Improper cleaning of the root canals
  • Failure to remove the infected pulp in its entirety
  • Improper diagnosis
  • Lack of clinician expertise
  • Compromised tooth condition

What are the signs and symptoms of root canal failure?

It is essential to identify the signs and symptoms of the failed root canal to act accordingly and get the tooth restored in time. some of the common signs and symptoms of a failed root canal are as follows –

Sensitivity to pressure

Typically, in this situation, the patient may feel mild tenderness to severe pain on biting or chewing food from the treated tooth. This also indicates the sign of inflammation around the surrounding tooth tissue.

Swelling around the tooth

One of the critical signs of a failed root canal is swelling around the concerned tooth. The swelling may be limited to the affected tooth or, in extreme cases, may extend to the patient’s face and neck. Usually, the swelling is tender to touch. However, it may not show any color changes. (2)

 Sensitivity to temperature

In cases of missed root canals, the pulp tissue is not entirely removed from the tooth. Therefore, it can lead to sensitivity to hot and cold food.

How to manage failed root canal symptoms?

If you notice the symptoms mentioned above, the first thing you must do is to contact your dentist and book an appointment. While in most cases, you may not get an immediate appointment. Therefore, during this time, you should be aware of the ways to manage the symptoms temporarily.

  • Over-the-counter pain medications such as ibuprofen and acetaminophen usually help to subside the tooth pain. However, it is best to talk to the dentist over the phone or follow previously prescribed medications. (3)
  • Swelling around the tooth can be managed by cold compressions. Apply ice pack on the swelling for two minutes and repeat it several times.
  • Antibiotics should be taken after a professional consultation. Usually, the dentist may prescribe antibiotics to ease the symptoms and limit the infection.

How is a failed root canal diagnosed?

During your appointment, the dentist physically examines the tooth and looks for signs of swelling or inflammation around the tooth. Furthermore, he may also palpate the gums and teeth to check for tenderness and pain.

X-ray studies provide a clear view of root canal failure. Usually, a periapical radiolucency around the treated tooth is an indication of a failed root canal. Other things that can be identified through the radiographic study are tooth root fracture, an extension of the tooth filling, status of the coronal seal, and the presence of accessory canal. (4)

What is the treatment for a failed root canal?

Treatment of a failed root canal mainly depends on the cause of failure, condition of the tooth, the type of root canal failure, the location and extent of infection. Typically, three main procedures can be performed to treat a failed root canal tooth. (5)

Re-root canal treatment

  • Conventional retreatment – in this situation, the tooth is treated with root canal treatment, which more or less follows the same steps as it did during the first root canal treatment. The old filling is removed, and the root canals are thoroughly cleaned. The dentist may also look for missed or accessory canals. The tooth is then filled again with gutta-percha and sealed.
  • Surgical retreatment – this involves apical surgery or the correction of the tip of the tooth root. It is done in cases where only the tip of the tooth root is infected. (6)

Intentional replantation

This is a unique procedure in which the tooth is extracted for the apical correction of the tooth root. The tooth is then carefully placed back into the socket to heal. This method is rarely followed in cases where apicectomy is not accessible through the gum tissue. (7)

Tooth Extraction

In most cases, the first line of treatment involves saving the tooth through retreatment. However, in cases where the infection has extended into the surrounding tissues, the dentist may have to remove the tooth.

Take away message

A failed root canal is one of the most uncomfortable and stressful situations for patients. Typically, during this condition, the patient may have tender teeth, swelling around the tooth, tooth sensitivity to pressure, and temperature.


A failed root canal can be caused by several reasons such as missed canals, presence of accessory canals, improper cleaning and filling of the root canal, tooth root fracture, and improper coronal seal. It is crucial to identify the exact cause of failure for appropriate treatment.

Usually, the cause of a failed root canal is determined by physical and x-ray examination. Treatment of failed root canal depends on the cause, condition of the tooth, and extent of infection. The retreatment of a failed root canal is one of the most common procedures performed by the dentist. However, in extreme cases, the dentist may plan for apicectomy, tooth extraction, or intentional replantation of the tooth.


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