All you need to know about cracked tooth after root canal

cracked teeth

What is a root canal treatment?

Endodontic or root canal treatment involves treating the inside of the tooth.

The tooth is covered by a hard tissue made up of two layers: enamel and dentin, which in turn covers a softer tissue called the pulp.

The pulp contains the nerves and blood vessels that feed the tooth throughout its life. If the pulp is affected, often by decay or other factors such as a fracture or gum disease, it becomes infected and must be removed.

Your dentist may tell you that you will need a root canal or endodontic treatment to empty and disinfect the inside of the tooth.

tooth structure

What is a cracked tooth?

A fractured or cracked tooth is a common injury that affects the hard tissues of the tooth (enamel and dentin).

It can appear as a line that crosses the tooth crown and can extend to the roots.

Today, tooth fracture risk is higher because people are keeping their natural teeth longer.

The tooth can fracture for multiple reasons, including tooth decay, trauma, biting a hard object, teeth grinding, or after a root canal treatment. The latter makes the tooth even weaker and more susceptible to damage.

Cracked teeth are the third cause of tooth loss and can affect people of all ages. They can cause intense pain when chewing and sensitivity to cold or heat.

How is a dental fracture diagnosed?

A cracked tooth may be visible or felt by your tongue if the fracture line is thick, but often it is hard to spot and requires a check-up by your dentist.

Your dentist will:
-Do a visual test: He or she will look for the fracture line to assess its extent and trajectory on the tooth.

Expose the tooth to a transilluminated light: Once the tooth is spotted, the crack can be highlighted by transillumination: a focused light source is applied to the different tooth surfaces to reveal any fractures.

-Remove the restoration: He or she may ask you to remove the restoration for direct access to the inside of the tooth. It is the most effective way to reveal dental cracks.

-Use an endodontic microscope: To better assess the cracks.

-Do a periodontal probing: Using an instrument, he will assess the tissue surrounding the tooth and reveal the approximate depth and severity of the underlying fracture.

-Do do exploratory surgery: Only done if a root fracture is suspected and cannot be revealed with other methods. The tissues that surround the tooth will be cleared to allow a direct view of the root.

-Do an x-ray examination: 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 cracks.

How does fracture occur after a root canal?

After endodontic treatment, the tooth is more likely to fracture, especially if it was already severely damaged.

Different types of fractures can occur. They can start from the crown, as in the case of fractured cusp or cracked tooth syndrome, or from the root, as in the case of vertical root fracture.

These fractures can occur spontaneously or be triggered by excessive forces on the tooth, such as biting a hard object or teeth grinding.

A cracked tooth after endodontic treatment may be asymptomatic, meaning that you will not feel anything.
But left untreated, the fracture can irritate the gums and lead to infection of the tissue surrounding the tooth. Symptoms can range from simple discomfort to intense pain when eating.

The pain does not come from the tooth since its nerves were removed during the root canal treatment. It comes from irritated periodontal tissues (tissues surrounding the tooth).

Among the different types of cracks that can occur on a tooth with a root canal treatment:

Vertical root fracture

vertical root fracture

This is the most common type of cracked tooth after endodontic treatment.
The fracture starts from the root and progresses to the crown.
The instruments used to thicken the canals of the tooth will weaken the tooth further and increase the risk of root fracture.

It is often associated with complications in the periodontal tissues (tissues surrounding the tooth including bone and ligaments). Indeed, bacteria will invade the space created by the fracture line and lead to an infection. Untreated, an abscess can form on the gum.

Fractured Cusp

fractured cusp

A fractured cusp is the easiest to reveal. It is a fracture that starts from the crown and ends at or slightly below the gum line.
Fractured cusp results from a weakening of the crown due to extensive decay or a large filling. After endodontic treatment, the crown of the tooth is even more fragile, which increases the risk of cracks.

Cracked tooth syndrome

cracked tooth syndrome

In cracked tooth syndrome, the fracture line doesn't break a tooth fragment as a fractured cusp does. The fracture line stops in the middle of the root.

The cracked tooth syndrome will continue to progress until it separates the tooth into two fragments, resulting in a split tooth.
The most common cause is insufficient protection of the tooth against biting forces and trauma caused by chewing hard and brittle substances (cereals, nuts, etc.).

Split tooth

split tooth

This type of fracture separates the tooth into two fragments.
Most often, it is the result of the progression of a crack that starts from the crown.
Symptoms include mobility of the tooth and discomfort when chewing. An abscess may appear on the gum due to the penetration of bacteria into the fracture.

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

A tooth with endodontic treatment and a branch of deadwood are similar in many ways. Both are emptied of their internal contents, for the tooth it is the nerve and for the wood, it is the sap.
They seem solid but in reality, they are fragile and can break at the slightest impact.

The major risk of most devitalized teeth is a fracture. This risk is even greater if the treatment is repeated.

A tooth with endodontic treatment is more sensitive than a tooth without treatment.
It is due to the absence of the pulp that supports the tooth throughout its life. The instruments used during root canal treatment will empty the tooth and thicken the canals making the tooth even more fragile.

Can a cracked tooth after a root canal be saved?

The treatment of cracked teeth after endodontic treatment depends on the type, extent, and location of the crack.

Usually, when the fracture is limited to the crown, the tooth can be saved by removing the fracture and protecting the tooth from further damage with a dental crown. But if the root is affected, the preservation of the tooth is difficult and extraction is necessary.

treatable and non-treatable cracked tooth

In the vertical root fracture

This fracture occurs mainly in teeth with root canal treatment.

Treatment options are limited. Extraction is often the only solution, especially in the case of complications or risk of infection.

If it is a back tooth with multiple roots (molar), it can be saved by removing only the fractured root and keeping the rest. This procedure will be followed by a restoration (crown placement) to protect the tooth.

root resection

A fracture that starts from the crown and progresses to the root

Treatment will depend on the extent of the fracture. If it exceeds one-third of the root, treatment is hopeless and extraction is necessary.

If the crack line does not extend beyond the gum line, the tooth can be saved.
First, the mobile fragment will be removed, and then your dentist will deem if the tooth is treatable. If so, he or she will prepare the tooth and cover it with a crown to protect it from further damage.

crowned cracked tooth

If the fracture line slightly exceeds the gum line, he or she may suggest a crown lengthening to restore the tooth afterward.

If the tooth is not treatable (due to a damaged tooth), extraction will be necessary.
After extraction, the missing tooth will be replaced with a bridge or an implant.
When dental cracks occur, it is impossible to stop their progression. So, the better way is to prevent them.

The safest option is to get a dental crown after the root canal treatment, which will protect your tooth from cracking.

Other measures you can take include:
  • Optimize your dental hygiene by brushing gently 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 an aggressive sport, wear a mouthguard to limit the damage to your teeth.
  • Avoid biting or chewing on hard objects, especially in the area where the root canal treatment is performed.

Complications of a cracked tooth with root canal treatment

A cracked tooth after endodontic treatment can have complications on the tissues surrounding the tooth, called the periodontal tissues.

The fracture line will present an entry point for bacteria to the periodontium, leading to periodontal infection.

Signs of periodontal disease include redness, swelling, and gums bleeding. Sometimes an abscess can appear in the gum, especially in the case of a split tooth and vertical root fracture.

Periodontal infection can affect your overall health through:
  • Fever.
  • Cervical adenopathy: swollen lymph nodes in the neck.
  • Increased heart and breathing rate.
  • Loss of appetite due to exacerbated pain during meals.