All you need to know about cracked tooth after root canal

cracked tooth after a root canal
Root canal, also called endodontic therapy, involves treating the inside of the tooth.

When the pulp, the soft tissue that carries the nerves and blood vessels, is infected or irreversibly damaged, it must be removed to save the tooth.

The downside is that although root canal therapy saves the tooth from extraction, it makes it weaker and more prone to fracture. This is why this procedure often comes hand in hand with a dental crown or restoration that will protect the tooth from further damage.

In this article, we will learn why the tooth is more likely to crack after a root canal, the symptoms, and the different treatment options.

Why are our teeth more likely to crack after a root canal?

A tooth with a root canal and a branch of dead wood can both be compared to fragile structures that are prone to cracking or fracturing.

They are both no longer living and have lost their inner content and, along with it, their strength and flexibility. In an endodontically treated tooth, the living tissue inside the tooth has been removed and replaced with filling material, making the tooth more brittle and susceptible to damage.

Similar to how a branch of dead wood can snap or crack easily under pressure or stress, an endodontically treated tooth can also fracture or break easily due to the loss of the tooth's natural internal support system.

The risk is even greater if the treatment is performed for the second time. Therefore, a solid restoration should be considered as soon as possible after root canal treatment to prevent this from happening.

How does your dentist diagnose the fracture?

A cracked tooth may be visible or felt by your tongue if the fracture line is thick. However, it can be hard to spot in its early stages. You may notice it until it leads to complications such as pain or a gum abscess. To diagnose the fracture, your dentist will:

  1. Do a visual test: He will look for the fracture line to assess its extent and direction on the tooth.

  2. Expose the tooth to light: Your dentist will expose your tooth to a light source to reveal any fractures.

  3. Remove the restoration: He may remove the restoration (filling or crown) to directly assess what is happening inside the tooth.

  4. Use an endodontic microscope: To better visualize cracks.

  5. Perform a periodontal probing: Using an instrument, he will evaluate the tissues surrounding the tooth to assess the extension of the fracture on the roots.

  6. Surgery: Only performed if a root fracture is suspected and cannot be revealed by other methods. The gum will be incised and peeled away from the tooth to allow a direct view of the root.

  7. Take an X-ray: 3D digital radiography allows a three-dimensional assessment of the cracked tooth. It is the best and least traumatic tool for the diagnosis of dental fractures.

How can a fracture occur after a root canal?

After root canal treatment, different types of fractures can occur. They may originate in the crown, as in the case of fractured cusp or cracked tooth syndrome, or the root for vertical root fractures.

Depending on the amount of damage to the tooth, the fracture may occur spontaneously or be triggered by excessive forces on the tooth, such as by biting a hard object or grinding or clenching the teeth.

1. Vertical root fracture

vertical root fracture

This is the most common type of crack that occurs after root canal treatment. The fracture starts from the root and progresses towards the crown. It is mainly the result of the treatment itself. The sharp instruments used weaken the tooth and increase the risk of root fracture.

A vertical root fracture is often associated with complications in the gum tissue. Indeed, bacteria will invade the space created by the fracture line and lead to an infection that can evolve into an abscess.


The treatment of root fractures is limited. Usually, the only solution is extraction, especially if it is a front tooth. In fact, vertical root fracture is the third most common reason for the extraction of an endodontically treated tooth.

In multi-rooted teeth (molars), there may be a few solutions to save the tooth. One of them is root resection or tooth hemisection, which consists of removing only the damaged part and keeping the healthy one.

root resection

2. Fractured Cusp

fractured cusp

A fractured cusp is the easiest to reveal. It is a fracture that starts at the crown and ends at or slightly below the gum line.
The fractured cusp results from a weakened tooth due to severe decay, a large filling, or excessive biting forces.


A tooth with a fractured cusp can usually be saved. If the fracture line does not extend beyond the gum line, your dentist will first remove the loose fragment and restore your tooth with a crown to protect it from further damage. However, if the damage extends into the roots, a crown lengthening procedure may be necessary before restoration.

crowned cracked tooth

3. Cracked tooth syndrome

cracked tooth syndrome

The fracture starts at the crown, in the center of the tooth, and progresses toward the roots. It most often affects the back teeth (molars and premolars). If left untreated, the cracked tooth syndrome can continue to progress until it splits the tooth in half. The cause may be a previously weakened tooth or an inappropriate restoration that did not protect the tooth from biting forces.


Treatment will depend on several factors. If the fracture line is limited to the crown, the tooth can be restored with a crown. However, if the fracture extends beyond the gum line and deep into the roots, extraction may be the only option.

4. Split tooth

split tooth

This type of fracture separates the tooth into two halves. It is most often the result of a crack that has not been treated.
Symptoms include tooth mobility, pain and discomfort when chewing, and sometimes a gum abscess. Find out more about split teeth here.

Can a cracked tooth after a root canal be saved?

As mentioned earlier, the treatment of cracked teeth after endodontic treatment depends on the type, extent, and location of the injury.

Usually, when the fracture is limited to the crown, the tooth can be saved by removing the loose fragment and protecting the tooth from further damage with a dental crown.

If the fracture has interfered with the root canal filling, your dentist may need to repeat the endodontic treatment to ensure that the infiltrated bacteria are removed.

But if the root is deeply affected, preserving the tooth can be challenging, and chances are high that the tooth will have to be removed.

Still, the best option for dealing with tooth fractures is to prevent them in the first place. The safest option is to get a dental crown as soon as possible. Here are some other steps you can take:

  • Optimize your dental hygiene by gently brushing your teeth at least twice a day with a soft-bristled toothbrush, flossing daily, and visiting your dentist every six months. Healthy teeth are less likely to be cracked.

  • If you grind your teeth at night or practice contact sports, consider getting a mouthguard to protect your teeth.

  • Avoid biting or chewing on hard objects, especially on the side of the treated tooth.

Complications of a cracked tooth with root canal treatment

A cracked tooth after a root canal may be asymptomatic, meaning you won't feel anything.

But if left untreated, the fracture can irritate the gums and lead to infection of the tissues surrounding the tooth. Symptoms can range from simple discomfort to severe pain when eating.

In extreme cases, an abscess may form near the damaged tooth. Symptoms may include redness, swelling, and pus discharge.

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  2. Vertical root fractures and their management https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4001262/
  3. An interdisciplinary approach to treat crown-root-fractured tooth https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3821233/
  4. An innovative approach for treating vertically fractured mandibular molar - hemisection with socket preservation https://www.jidonline.com/article.asp?issn=2229-5194;year=2012;volume=2;issue=2;spage=141;epage=143;aulast=Agrawal
  5. Novel Matricing Technique for Management of Fractured Cusp Conundrum – A Clinician’s Corner https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4866268/