Root Canal Treatment Frequently Asked Questions (FAQ)


What is root canal treatment treatment?

The middle of each tooth contains the dental pulp - living tissue consisting largely of small arteries, veins and also nerves. When the tooth has a crack, or deep caries (tooth decay) or deep filling because of caries, bacteria can get in to the dental pulp causing an infection.

Dental pulp infection

As the soft tissue of the dental pulp is enclosed by the hard, unyielding structure of the tooth, there is little room to accommodate any expansion caused by swelling of the dental pulp (see rollover image left for normal tooth structure). Consequently, the swelling causes considerable pain, and can sometimes seem to throb with your heartbeat! The infection can also cause the dental pulp to undergo necrosis (commonly termed as the "death of the pulp"), and also spread through the ends of the root into the surrounding bone. When the bacteria is virulent, or the person's immune system down, an abscess may develop, resulting in a swelling as the pus builds-up. The pressure from the build-up of pus usually causes pain.

Sinus Tract

Occasionally, the pus may track towards the gum surface, to discharge through a pimple-like swelling on the gum surface (fig. left). This is known as a sinus track, or commonly called a "gum boil". It is not always as obvious as this picture. Sometimes it is just a little pimple. As this sinus track acts like a pressure relief valve, there is usually no pain, therefore, you may not be aware of any problem.

As the dental pulp tissue is irreversibly damaged, it will need to be removed to alleviate the pain and remove the source of infection. This can be achieved in one of two ways.

Cleaning and shaping the root canal with files
  1. The whole tooth is removed or extracted.
  2. Root canal treatment:
    • The infected dental pulp tissue in the root canal is removed.
    • The root canal cleaned and disinfected (fig. left).
    • The now empty root canal is then filled with a solid filling material together with a sealer to prevent further ingress of bacteria (rollover image).
The canal is root filled with gutta percha coated with cement

This way the tooth is conserved and remains in function. Once the source of infection is removed, any infection of the surround bone will also heal.

After root canal treatment, the tooth will have to be suitably restored for it to maintain its function, usually with a crown.

How successful is root canal treatment?

Studies indicate a success rate of between 90-95% for root canal treatment. The root canal system of many teeth are very complex, and it may not be possible to clean and disinfect all areas of the root canal system. Should a virulent or opportunistic bacteria be left behind, or track down the root canal through new cavities or a dislodged restoration, there could be a recurrence of the infection. In this case retreatment may have to be done. The success rate with retreatment of recurrent root canal infection is around 60-65%. Sometimes there could be a crack in the tooth through which bacteria can track down from the mouth into the bone too, causing a recurrent infection. Where the root has a crack, the offending root or the whole tooth usually needs to be extracted.

Is root canal treatment painful?

Root canal treatment is usually not painful when adequate anaesthesia can be obtained. In a small proportion of cases when root canal treatment is performed on teeth that are acutely painful, it is more difficult to obtain adequate numbness with routine local anaesthetic methods. However, an experienced dentist should be able to adopt various alternative methods to obtain adequate numbness to perform root canal treatment.

Following root canal treatment, there is a possibility of some post-operative pain or tenderness on biting the tooth as a reaction to the treatment. Post-operative pain is usually far less than the pain that brought you in for treatment in the first place. Should you experience post operative pain, it can usually be alleviated with commonly used over the counter painkillers such as 2 tablets of 500mg paracetamol every 4-6 hourly or 400mg Ibuprofen every 4-6 hourly.

Post operative pain should diminish over time. If instead, it seems to be getting more severe, then see your dentist.

Must a tooth be crowned after root canal treatment?

Teeth that require root canal treatment often already have extensive fillings. In addition, a cavity must be drilled through the middle of the tooth to reach the dental pulp. The loss of tooth structure, when extensive, makes the tooth more prone to fracture through fatigue failure over time. Therefore, should your dentist judge that under your bite force (which can vary considerably in different people) there is a risk of cracking or fracturing your tooth, may recommend a restoration that covers the whole biting surface of the tooth to “splint” or hold it together. The crown is the most commonly used, though other types of restorations that can hold the tooth together to reduce the risk of fracturing, could also be used.