Tooth pain persisting even months after root canal treatment

Tooth pain persisting for months after root canal treatment
Why do we feel pain in a tooth that has had a root canal since it no longer has any nerves?

Well, pain a few days after treatment has nothing to do with the tooth itself. The instruments used during the procedure may have caused some slight injury to the tissues around the tooth, leading to inflammation. But this is just a temporary side effect and should go away in a few days.

However, pain that persists for several months after the procedure is abnormal.

When this happens, it does not necessarily mean that the pain is coming from the treated tooth. Other surrounding structures (sinuses, bones, nerves, etc.) may also be involved. The best thing to do in this case is to consult your dentist or endodontist to assess and address the situation.

In this article we will discuss when pain after root canal treatment is abnormal, the potential causes of persisting pain months after root canal treatment, and the different solutions.

What does it mean when pain persists for months after root canal treatment?

Pain after root canal treatment that lasts longer than expected or suddenly appears months or years later is a common sign of treatment failure. But first, you must make sure that the pain does not involve other structures around the tooth, namely the gums, sinuses, muscles, or joints.

To determine if a root canal has really failed, your dentist will take X-rays of your tooth to examine the root and surrounding bone for signs of infection or other issues that may be causing pain or discomfort.

X-rays and root canal failure

Now, root canal treatment is a successful procedure that aims to save an irreversibly damaged tooth from extraction.

Postoperative pain is not uncommon. It is reported by 25-40% of patients.

The pain usually decreases within two days after the procedure. According to one review, its frequency drops from 80% to 40% after the first 24 hours and to 11% after the first week.

On the other hand, pain that persists or appears months later is called chronic. It is less common and occurs in 5.3% of cases, according to a review.

Chronic pain may indicate that the initial inflammation after surgery has not healed and continues to damage your tissues.

Sometimes, even if your root canal treatment was successful and your tooth healed well, it can get infected again, even years later. This may happen if bacteria or saliva leaks into a tooth that wasn't restored properly. You might feel more pain when you bite, see redness and pus around the tooth, and notice a bump on your gums. That's called an abscess.

My tooth still hurts months or a year after the root canal: The potential causes

Pain that persists or suddenly appears several months after a root canal can be frustrating for you and your dentist, especially if the healing process has gone well and everything seems normal.

Treatment begins with identifying the root cause of the pain. It may be related to the tooth itself (odontogenic pain) or involve another structure (non-odontogenic pain).

1. Pain related to the tooth itself:

Persistent pain after a root canal often comes from the tooth itself. Usually, an x-ray can identify the problem by revealing what is hidden inside the filling. The most common factors are:

1. Something is wrong with the root canal filling:

The main goal of a root canal is to disinfect and fill the inside of the tooth without leaving a gap where bacteria can grow.

If the filling material extends beyond the root tip, you may experience pain in the hours or days following treatment.

However, when a gap is left in the root canals, you may not feel anything at first. But bacteria will exploit this space to grow silently and affect the area around the root tip. Months or years later, an infection can occur, leading to intense spontaneous pain, aggravated when chewing.

2. A missed canal:

Sometimes the tooth has an extra canal that can be difficult to find, even with an x-ray. If a canal is missed, your tooth will continue to hurt even after the procedure.

When your dentist suspects an extra canal, he may suggest a 3D x-ray for a three-dimensional assessment of your tooth's root canal system. This type of radiography is more accurate and useful in the presence of complex dental anatomy.

Once the presence of a missed canal is confirmed, you will need to repeat the root canal treatment.

3. Fracture:

A tooth with a root canal is more fragile and susceptible to cracking than a healthy tooth. This is especially true if it is not properly restored with a crown. The chewing forces can weaken it further and increase the risk of fracture.

When this happens, it can irritate the gums around the tooth and cause intense pain when you bite. In its advanced stages, it can allow bacteria to get into the tissues surrounding the tooth, leading to infection and a gum abscess later on.

Treatment of a tooth fracture depends on its location and extent. The deeper the fracture line, the more difficult it is to save the tooth. However, if the fracture does not extend beyond the gum line, the tooth may be restored with a dental crown.

4. The root canal was performed on the wrong tooth:

Although rare, a healthy tooth may be treated instead of the infected one. In this case, the same pain will persist after the procedure.
In other cases, a nearby tooth decays and starts to hurt, making you think the pain is coming from the root canal tooth. You may not notice this, especially if the decay is hidden between the teeth.

5. The tooth is in a high position:

If the tooth sits higher than the rest of the teeth, it will receive more pressure, which will put a lot of stress on the tissues around it. This can also lead to persistent pain.

2. Other causes of pain not related to the tooth:

In other cases, the pain may have nothing to do with the root canal work. Potential causes include:

1. Sinus pain:

The sinuses are bony cavities located in the cheek area, next to the nose and above the upper back teeth. Sinusitis is when inflammation occurs in these areas.

One possible cause is an infection of the back teeth. Because the roots of these teeth are close together, bacteria can travel up into these bony cavities and cause sinusitis. A root canal can also irritate the sinus tissue and cause the same symptoms.

The typical sign of sinusitis is pain or pressure around the nose area that gets worse when you change your posture (throw your head forward). Sometimes the pain can spread to other areas, such as the eyes and upper teeth.

2. The gum between the teeth hurts:

The area between your teeth is the most sensitive part of your gums. The accumulation of food debris in this region can lead to inflammation with bleeding and intense, radiating pain that worsens during meals. This can be associated with halitosis or bad breath. This condition most often occurs when the teeth do not touch properly, often due to an ill-fitting restoration.

3. Joint pain:

The joints that connect our lower jaw to the skull are called temporomandibular joints (TMJ).

Temporomandibular disorders are the second most common cause of facial pain after toothache. They can affect muscles, joints, and nerves and interfere with everyday oral functions such as chewing, opening the mouth, and speaking.

Joint pain can sometimes spread to the teeth and mimic a toothache. The most common symptoms are dull, aching pain in the jaws and joints, difficulty chewing and opening the mouth, and an annoying clicking sound when chewing or opening the mouth.

4. Nerve damage (neurogenic pain):

Neurogenic pain is defined as dysfunction of the nervous system in the absence of visible injury or disease.
The diagnosis is made when all other possible causes have been ruled out.
It is the most challenging situation as the tooth and x-ray may not show anything abnormal.

The condition most known to cause persistent pain for more than six months despite dental treatments is atypical odontalgia.
One study showed that 3-6% of patients who underwent root canal treatment have atypical odontalgia.
The pain is usually persistent and continuous, of variable intensity, referred to as a burning sensation or an electric shock. But in most cases, it remains moderate and does not prevent sleep.

As the pain can affect different sites at the same time, it can be difficult to pinpoint the specific area where the pain is originating.

The mechanisms involved are still unclear, but many authors agree on the involvement of a nerve injury. The root canal procedure can injure a nerve and cause unexplained and persistent pain for months or years.

The lack of data and knowledge about such conditions often leads to unjustified dental treatments such as extraction, which only aggravate the symptoms.

When does extraction become the only solution?

Root canal treatment has a high success rate that can last for years or even a lifetime as long as you maintain good oral hygiene.

However, the treated tooth may become re-infected, and you may experience pain again.

In this situation, it is often possible to have a second treatment. But if the tooth is fractured, the root is deeply decayed or the bone loss is severe, there is no other solution than to extract the tooth.


In conclusion, persistent pain several months after root canal treatment is rare. Some factors significantly increase this risk. For example, women are 3.8 times more likely to suffer from chronic pain. In addition, the risk is even higher if the tooth had already been painful for more than three months before treatment.
Treatment begins with identifying the cause. Once the cause is eliminated, you will get relief.

  1. Atypical odontalgia--an update. https://europepmc.org/article/med/23097829
  2. Comparison of postoperative pain after root canal treatment using reciprocating instruments based on operator’s experience: A prospective clinical study https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5549583/
  3. Doctor, why does my tooth still hurt? And what can you do about it? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3697825/
  4. Pain prevalence and severity before, during, and after root canal treatment: a systematic review https://pubmed.ncbi.nlm.nih.gov/21419285/
  5. Frequency of persistent tooth pain after root canal therapy: a systematic review and meta-analysis https://pubmed.ncbi.nlm.nih.gov/20113779/