Root Canal Treatments - Causes

Authored by Dr Ben Williams, 09 Jul 2017

Reviewed by:
Dr Hayley Willacy, 09 Jul 2017

Tooth decay (dental caries)

Deep dental cavities contain millions of germs (bacteria). As they spread through the dentine they will cause pulp inflammation and toothache which if left untreated will eventually kill the pulp. The bacteria will continue to pass through the dentine until they have infected the dead pulp space.

Dental injury

This is usually due to an accident, sporting injury or assault:

  • Periodontal trauma (injury to the gum, bone and ligaments around a tooth): if a tooth receives a sudden blow, the root will be forced against the bone. Often this just results in minor tenderness when biting for a few days but in severe cases, the vulnerable area where the nerves and blood vessels of the pulp enter the root apex may be crushed or severed. This will result in the death of the pulp inside the tooth because its blood supply has been stopped. Depending on the type and severity of injury the dead pulp space may remain free of bacteria or it might become infected.
  • Tooth fracture: moderate or large fractures can damage or expose the dental pulp, resulting in severe pulp inflammation, pulp infections and pulp death. Prompt dental treatment will improve the chances of preserving pulp vitality, keeping the pulp alive, but in severe cases tooth extraction or root canal treatment (RCT) will be necessary.

Front teeth are more vulnerable to both types of dental injury but back teeth with cavities or fillings can also fracture too. Custom made mouth guards are the most effective way to protect your teeth if you participate in activities which pose a risk of dental injury.

Dental treatment

Many dental procedures will cause temporary pulp inflammation, which resolves after a few days. Occasionally, usually after extensive decay removal, the inflammation will be severe and result in the death of the pulp. Your dentist should advise you of this risk before commencing certain procedures - for example, when preparing a tooth for a crown or placing a very deep filling. Orthodontic treatment can also cause pulp death if braces are tightened too quickly.

Occasionally it may be necessary to remove a healthy tooth pulp in order to utilise the space within the root canal and pulp chamber to support a filling on worn or damaged teeth. Removing a healthy pulp is called elective devitalisation.

If a pulp dies without becoming infected by bacteria it will decompose yet might cause little or no bone damage at the root apex. The tooth may be tender to bite on to or it could be symptom-free. Frequently the only indication that your tooth might have a dead pulp is a change in colour from white to grey, usually over several months or years. If the tooth is structurally sound then RCT is usually the treatment of choice but, occasionally, if there are no symptoms or signs of bone damage at the root tip, it may be acceptable to simply monitor the tooth with an X- ray every few years. If the review X-rays indicate any bone changes at the root apex then RCT will be necessary.

If a dead or dying pulp becomes infected with bacteria, usually due to deep dental decay or moderate to severe tooth trauma, they will multiply and spread via the root canal out into the bone. This will make the tooth painful to bite on to. As more bone is destroyed, the infection can pass through the bone to the soft tissues which might relieve the pressure under the tooth and possibly stop the pain on biting. If the infection passes from the bone to the gum it will form a localised infection called a dental abscess, or gum boil. If these types of abscess are addressed promptly by a dentist they are not usually very serious. They do not require antibiotics and tend to heal well after RCT or extraction. However, if the infection passes through the bone below the level of the gums it can form a spreading soft tissue infection which is more serious. Usually a spreading dental infection is seen as a painful swelling of the cheek or under the lower jaw; however, in severe cases it can obstruct the airway, cause total loss of vision or even infect the brain. All spreading dental infections should be assessed urgently by a dentist. They can develop in only a few hours, so if you think a dental infection may be the cause of a facial swelling that affects your ability to breathe or swallow, or is causing your eyelids to swell and close, you should seek urgent medical/dental advice.

Further reading and references

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