Why does my tooth need another root canal treatment?

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The aim of a root canal treatment is to clean the bacteria out of the tooth’s root canals and prevent re-colonization using a tightly sealed root canal filling. But if bacteria remain in the canal system, these can multiply again, if

  • Canals were overlooked
  • Canals were not treated along enough of their length or width.
  • The effect of the cleaning was not sufficient due to complex canal anatomy

Another reason for reinfection caused by bacterial colonization of the filled canal system can be a root canal filling that is exposed to saliva and the bacteria it contains. This is often the consequence of tooth decay or treatment with a filling or crown that is done too late.

If my tooth is “dead” why does it still hurt?

During root canal treatment the vascular nerve bundle is removed from within the root. But the tooth is embedded in a tooth socket which can become inflamed. If bacteria from within the tooth cause acute inflammation of the tooth socket, this can result in pain, swelling and pus formation.

If I am not in pain does that mean my tooth is healthy?

With chronic forms of infection there is often no discomfort at all. It is not uncommon for the consequences of the infection to only be discovered on an X-ray. The dental surgeon sees that bone has disintegrated from around the root of the tooth. This degradation is progressive and can turn into acute inflammation with pain, swelling and pus formation.

What can the dentist do so that I can keep my tooth?

Only if it is possible to thoroughly clean the bacteria out of the root system can the infection be eradicated, thus allowing the bone to heal.


First the tooth is isolated from the mouth cavity using a rubber cloth (dental dam). For one thing this prevents the bacteria from the saliva getting into the tooth and for another thing it prevents foreign objects from going down your throat.


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First the dentist has to remove the existing filling from the canals. If the tooth has a dental post this must also be taken out.

Depending on the type of material used in the root canal filling and the type of dental post, removal can be very difficult and very time-consuming. Magnification systems (such as magnifying spectacles or a microscope) are very helpful for this and sometimes even essential in order to clearly see the smallest details and perform treatment while protecting healthy material.


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It is also important to thoroughly clean the whole canal system. If the old root canal filling did not completely fill the canal system, the untreated parts must also be accessed. If this is successful, the root canals can be cleaned using fine instruments and disinfectant rinses.


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After the canal has been thoroughly cleaned, the dental surgeon fills the root canal system. The access through the crown of the tooth is initially temporarily sealed with a filling material.

Can all teeth be preserved using retreatment?

Any medicinal therapy has its limits. In complex cases it can be impossible to completely clean the canal system. Sometimes a surgical procedure also has to be carried out in order to preserve the tooth.