What to do when a Root Canal Fails


Root Canal Fails

Root canal treatment is a common dental procedure designed to save a tooth that has been severely damaged or infected. While the success rate of root canals is high, failures can occur. Understanding the causes, symptoms, and treatment options for a failed root canal can help you take the necessary steps to address the issue promptly and effectively.

Understanding Root Canal Treatment

What is a Root Canal?

A root canal, also known as endodontic therapy, is a dental procedure used to treat infection or damage within the pulp of a tooth. The pulp contains nerves, blood vessels, and connective tissue, and when it becomes infected or damaged, it can cause severe pain and lead to further complications if not treated.

Purpose and Procedure

The primary purpose of a root canal is to remove the infected or damaged pulp, clean and disinfect the inside of the tooth, and then fill and seal it to prevent further infection. The procedure typically involves the following steps:

  1. Anesthesia: The dentist administers local anesthesia to numb the affected area.
  2. Access Opening: An opening is made in the crown of the tooth to access the pulp chamber.
  3. Pulp Removal: The infected or damaged pulp is removed using specialized instruments.
  4. Cleaning and Shaping: The root canals are cleaned, shaped, and disinfected.
  5. Filling and Sealing: The cleaned canals are filled with a biocompatible material, usually gutta-percha, and sealed.
  6. Restoration: A crown or filling is placed on the tooth to restore its function and appearance.

Causes of Root Canal Failure

Incomplete Removal of Infected Tissue

One of the most common reasons for root canal failure is the incomplete removal of infected tissue. If any infected pulp remains, it can lead to persistent infection and pain.

Complex Canal Anatomy

Teeth can have complex canal anatomies, including multiple or curved canals that are difficult to clean thoroughly. Missed canals or incomplete cleaning can result in treatment failure.

Cracks or Fractures in the Tooth

Cracks or fractures in the tooth can allow bacteria to re-enter and infect the tooth, leading to root canal failure. These cracks can be difficult to detect and may occur during or after the procedure.

Poor Restoration

A poorly fitted or delayed restoration, such as a crown, can compromise the seal of the root canal, allowing bacteria to re-enter and cause reinfection.

Coronal Seal Breakdown

The coronal seal is crucial for preventing bacteria from entering the treated tooth. If this seal breaks down due to poor restoration or damage, it can lead to reinfection.

New Decay or Trauma

New decay or trauma to the treated tooth can expose it to bacteria, leading to reinfection and root canal failure.

Signs and Symptoms of a Failed Root Canal

Persistent Pain

Persistent or recurrent pain in the treated tooth is a common sign of root canal failure. This pain may be constant or occur when biting down.

Swelling and Tenderness

Swelling and tenderness in the gums around the treated tooth can indicate an ongoing infection or inflammation.

Tooth Sensitivity

Sensitivity to hot or cold temperatures that lingers after the root canal procedure may signal unresolved issues within the tooth.

Abscess Formation

The formation of a dental abscess, a pus-filled pocket, in the surrounding gums is a clear sign of infection and root canal failure.

Tooth Discoloration

Discoloration of the treated tooth, such as a grayish tint, can indicate that the tooth is not healing properly.

Discharge from the Tooth

Discharge of fluids, such as pus, from the treated tooth is a sign of infection and requires immediate attention.

Diagnostic Methods

Clinical Examination

A thorough clinical examination by a dentist or endodontist can help identify signs of root canal failure, such as swelling, tenderness, and discharge.

Radiographic Evidence

X-rays are essential for diagnosing root canal failure. They can reveal persistent infection, abscesses, and other issues that may not be visible during a clinical examination.

Treatment Options for a Failed Root Canal

Root Canal Retreatment

Retreatment involves removing the existing root canal filling, cleaning and disinfecting the canals again, and refilling and sealing the tooth. This is often the first line of treatment for a failed root canal.


An apicoectomy is a surgical procedure that involves removing the tip of the tooth’s root and any surrounding infected tissue. The end of the root is then sealed to prevent further infection.

Tooth Extraction

In cases where the tooth cannot be saved, extraction may be necessary. The extracted tooth can be replaced with a dental implant, bridge, or denture to restore function and appearance.

Preventing Root Canal Failure

Proper Oral Hygiene

Maintaining good oral hygiene is crucial for preventing root canal failure. Brush and floss your teeth regularly to remove plaque and bacteria.

Regular Dental Check-ups

Regular dental check-ups allow your dentist to monitor the health of your teeth and catch any issues early before they lead to root canal failure.

Immediate Restoration

Ensure that the treated tooth is restored promptly with a crown or filling to protect it from bacteria and prevent reinfection.

Avoiding Hard Foods

Avoid chewing on hard foods, such as ice or hard candies, which can crack or damage the treated tooth and lead to root canal failure.


Root canal treatment is a highly effective procedure for saving damaged or infected teeth. However, failures can occur due to various reasons, including incomplete removal of infected tissue, complex canal anatomy, and poor restoration. Recognizing the signs and symptoms of a failed root canal and seeking prompt treatment can help prevent further complications. By maintaining good oral hygiene, attending regular dental check-ups, and protecting the treated tooth, you can reduce the risk of root canal failure and ensure the long-term health of your teeth.

What Are the Most Common Signs of a Failed Root Canal?

Common signs include persistent pain or discomfort in the treated tooth, swelling or tenderness in the gums around the tooth, the appearance of a pimple-like bump on the gums (dental abscess), tooth discoloration, and increased sensitivity to hot or cold temperatures.

Can a Tooth Be Saved After a Root Canal Failure?

Yes, in many cases, a tooth can be saved even after a root canal failure. Treatment options like retreatment, apicoectomy, or, in some cases, tooth extraction followed by dental implants or bridges can be effective in addressing the issue.

How Long After a Root Canal Can It Fail?

Root canal failure can occur shortly after the procedure or several years later. Early failures are often due to procedural complications, while later failures might result from new decay, fractures, or gum disease affecting the tooth.

What Causes a Root Canal to Fail?

Complex root canal anatomy, undetected canal branches, procedural errors, tooth cracks, and recontamination of the tooth as a result of decay or gum disease are just a few causes of root canal failures.

Is Retreatment for a Failed Root Canal Painful?

Retreatment procedures are generally performed under local anesthesia, making them as painless as possible. Most patients report discomfort similar to or less than that of the initial root canal procedure. Your dentist or endodontist will take all necessary steps to ensure your comfort during the treatment.

Root Canal Fails

What to do when a Root Canal Fails


Discover the signs of a failed root canal and explore effective solutions. Our in-depth guide covers retreatment options, prevention tips, and expert insights to help you make informed decisions about your dental health.

Practical Oral Health Care Tips to Prevent Dental Problems

Unlock a Lifetime of Healthy Smiles: Practical Oral Care Tips


Discover practical tips for maintaining excellent oral health and preventing dental problems. From proper brushing to dietary habits, this guide covers all you need for a lifetime of healthy smiles.

Cracked Tooth Crisis

Cracked Tooth Crisis: Your Comprehensive Guide to Types, Causes, Symptoms & Treatment


A cracked tooth can be a dental emergency that requires immediate attention. If left untreated, it can lead to severe ...