What is Root Canal Infection? – Cause, Symptoms, & Treatment

Root canals are typically the part of the tooth root that contains the vital pulp tissues – nerves and blood vessels of the tooth. Root canal plays a crucial role in preserving and protecting the pulp tissue. However, extensive tooth decay, fracture of the tooth or root, gum disease, and bone infections can spread to the pulp, causing infection in the tooth. In such situations, root canal therapy is the treatment of choice.

The American Association of Endodontics has recorded over 15 million root canals performed every year in the United States. It is essential to identify the symptoms of root canal infection. Some of these symptoms include severe toothache, gum swelling, and a bad taste in the mouth. Today’s article will highlight the causes and symptoms of root canal infection. Furthermore, we will discuss the treatment of root canal infection.


What is root canal infection?

The tooth is made from several layers, namely the enamel, dentin, and pulp. Enamel is the hardest mineralized layer of the tooth. dentin is porous, and the pulp tissue consists of a network of blood vessels and nerves. (1)

Root canals are typically a part of the tooth root that contains the pulp tissue. Root canal infections are prevalent in the United States. Like any other tooth infection, root canal infections can also spread to the surrounding gum tissue.

The extent of infection depends on how soon the person gets the treatment. In severe cases, the disease can also spread to the bone lead to tooth loss. (2)


Usually, the patient may feel pain and discomfort. However, the symptoms can worsen as the infection spreads further into the surrounding tissue. Some of the common signs and symptoms of root canal infection include –

  • Gum swelling
  • Large tooth cavity
  • Inflammation of the pulp
  • Severe pain that only subsides with medication
  • Facial swelling
  • Tenderness around the affected tooth (3)
  • Tooth discoloration
  • Pus discharge
  • Bad taste in the mouth


There are several causes of root canal infection. some of them include –

  • Undetected root canal infection due to the complicated shape of the root canal
  • Presence of narrow or curved canals that are not adequately cleaned and disinfected during the root canal treatment.
  • Presence of accessory or lateral canal that house the harmful bacteria in the tooth and has the potential to reinfect the tooth
  • Delayed restorative treatment post-root canal therapy can lead to leakage of harmful bacteria back into the tooth (4)
  • Spread of infection from the surrounding gum into the tooth root
  • A deep fracture that hasn’t been treated for a long time
  • Secondary tooth decay of the treated tooth


Typically root canal infections are treated with endodontic treatment or root canal therapy. Re-infection is a root canal treated tooth may lead to re-treatment of the tooth. in both cases, the root canal treatment is performed in the following way –

  • The infected tooth is examined, and the extent of the infection is recorded using dental x-rays.
  • The dentist usually numbs the tooth and the surrounding soft tissue with a local anesthetic.
  • A protective barrier, such as a rubber dam is placed to isolate the tooth and prevent saliva contamination. (5)
  • The dentist drills the tooth to clean the decayed portion and reach the canal orifice.
  • Once the calas are open, endodontic files are used to clean the canal and remove the infected pulp tissue.
  • Once the canals are all clean and disinfected, the tooth is then filled with a rubber-like material called the gutta-percha – latex-based polymer.
  • After filling the root canal, the tooth is sealed using a permanent tooth, usually filling amalgam or composite.
  • The filled tooth is then trimmed and prepared to allow the dental crown to fit correctly and strengthen the tooth structure. This protects the tooth from future infections.


It is essential to understand the importance of preventing root canal infection. Nobody likes to experience the pain and discomfort that occurs due to root canal infection. some of the preventive tips that you can follow to have healthy teeth hare as follows –

  • Brush and floss your teeth regularly at least two times in a day
  • Use an antiseptic mouthwash to increase the efficiency of oral health routine
  • In the case of soreness, you can use over-the-counter pain medications such as ibuprofen and acetaminophen
  • Always follow up your routine dental appointments to stay clear of any developing dental infection(6)
  • Get professional tooth cleaning at least two times in a year
  • Do not delay the treatment for any dental infection

Take away message

Root canal infections are one of the most painful tooth infections one can experience in their life. Usually, the root canal is a part of the tooth root that contains the vital pulp tissue. A wide range of reasons can cause root canal infections. Some of them include infection spread from the surrounding tissues, re-infection of a treated tooth, improper cleaning of the tooth, tooth decay, and fracture of the tooth.

The typical signs and symptoms of root canal infection include severe pain, discomfort, gum swelling, bad taste in the mouth, and signs of tooth decay. It is essential to understand the signs and symptoms and get prompt treatment.


Usually, the treatment for root canal infection includes root canal therapy. The best way to stay healthy and prevent root canal infection is to follow regular oral hygiene.


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