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What Are Root Canal Infections, Know its Causes, Symptoms, Prevention

Teeth are made up in several layers, with the hard outer surface known as enamel. Enamel is the hardest layer of the tooth. The layer under the enamel is known as dentin, which is a sponge-like, porous tissue. The inner-most layer present at the center of each tooth is known as the pulp, and it is a collection of soft tissue. The nerves and blood vessels that help the tooth grow are present inside the pulp. The pulp also contains cells known as odontoblasts that are responsible for keeping the tooth healthy.

A root canal treatment removes the pulp of the tooth that has become infected or has been damaged due to tooth decay, or any other type of injury. Root canal treatment helps remove bacteria from the infected tooth, prevents re-infection of the tooth, and can help save the natural tooth. A root canal treatment is a very common type of dental procedure today and are known to be very safe.(1)

Infections following a root canal treatment are not common, but there is a small chance that the tooth on which the procedure has been performed ends up becoming infected after the root canal has been completed.

Here is everything you need to know about root canal infections, their symptoms, and what you can do to prevent them.

Causes of a Root Canal Infection

There are many causes of why a tooth becomes infected following a root canal treatment. Some of these causes include:

  • The tooth might have curved or narrow canals that did not get cleaned and disinfected properly during the root canal.
  • The shape of the root canals could be challenging, and the areas of infection could have gone undetected during the root canal procedure.
  • The tooth might have extra accessory canals that might be housing bacteria that can infect the tooth again.(2)

If you delay the placement of a crown or permanent restoration after the root canal, it can allow harmful bacteria to grow back into the tooth, leading to infection.

The tooth might have developed a new cavity after the root canal, or it might have gotten damaged or cracked, causing a new root canal infection to develop.

Symptoms of a Root Canal Infection

Symptoms of a Root Canal Infection

It is normal to experience a little bit of pain after undergoing a root canal procedure. You are also likely to feel some discomfort and tenderness in the area that is going to last for a couple of days following the treatment. You may even have mild pain for up to a week afterward as well.

If you continue to feel high-intensity pain for more than a week after the root canal has been performed, then you should go back and see your dentist, especially if the pain seems to be worse than before the procedure was done.

In some cases, you may contract a delayed root canal infection on a tooth that has been pain-free before. The tooth that was treated by a root canal procedure might not heal completely and may end up becoming painful or infected in some months or even years after a root canal.

Here are the common symptoms of a root canal infection that warrants you to pay another visit to your dentist:

  • Pain and discomfort that ranges from mild tenderness to unbearable pain in the tooth on which the procedure was performed. The pain seems to increase when you apply pressure due to eating or while pressing on the tooth. Exposure to extreme temperatures also causes pain.
  • Pus discharge from the tooth – pus might be yellowish or greenish in color
  • Swollen and red tissue near the tooth, particularly on the gums around or underneath the tooth. Swelling can spread to your face and neck as well in some severe cases.
  • Discomfort or tenderness in swollen tissue, especially when you apply pressure to it or touch that area
  • A bad taste in the mouth
  • Bad breath from the infected tissue(3)

Can A Root Canal Infection Spread?

Just like any other infection, it is possible for a root canal infection also to spread to the surrounding tissue in the mouth. This means that the infection can spread to other teeth, the gums, and the tissue in the cheeks and face as well. Keep in mind that the infection will not go away or heal until it is treated, and the longer you wait to get it treated, the more likely it is that the infection will spread more.

How to Prevent Root Canal Infections?

There are several steps you can take to prevent the development of an infection after having a root canal procedure. This involves taking good care of your teeth after you have a root canal. Here are some tips to keep your teeth healthy and free of infection:

  • Brush and floss at least two times a day.
  • Use an over-the-counter pain medication such as ibuprofen if you experience some tenderness and pain after the root canal.
  • Use a gentle but antiseptic mouthwash for the first couple of days after the root canal. Afterward as well it is recommended to use an antiseptic mouthwash itself to prevent any chances of an infection.
  • Make sure that you go back to your dentist for permanent restoration or a final crown as soon as possible after the treatment. This will completely seal the root canal from any bacteria and also keep your tooth safe.
  • Opt for getting dental cleanings done at least twice a year. This helps keep your teeth healthy, and your dentist will also be able to catch any tooth decay or tooth infections at an early stage.
  • If you notice any early symptoms of an infection, do not delay visiting your dentist. The earlier a root canal infection is diagnosed, the faster you will get better, and the lesser damage will be caused to your tooth.


  1. American Association of Endodontists. (2020). Quick Endodontic Facts – American Association of Endodontists. [online] Available at: https://www.aae.org/specialty/about-aae/news-room/endodontic-facts/ [Accessed 25 Feb. 2020].
  2. Sundqvist, G., 1992. Associations between microbial species in dental root canal infections. Oral microbiology and immunology, 7(5), pp.257-262.
  3. Kini, V.V., Pereira, R., Padhye, A., Kanagotagi, S., Pathak, T. and Gupta, H., 2012. Diagnosis and treatment of halitosis: An overview. J Contemp Dent, 2(3), pp.89-95.

Also Read:

Sheetal DeCaria, M.D.
Sheetal DeCaria, M.D.
Written, Edited or Reviewed By: Sheetal DeCaria, M.D. This article does not provide medical advice. See disclaimer
Last Modified On:March 6, 2020

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