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How can a root filled tooth be painful?

Updated: Dec 13, 2018

We often seen patients who have had root fillings in the past but the teeth then become painful again. This article discussed one way a tooth which had previously been treated became infected and how we were able to treat it.


One purpose of a root filling is to remove bacteria from inside a tooth. If the entire space inside a tooth has not been disinfected, this bacteria can proliferate over time and a tooth can become infected again.

Infection above root filled tooth healing after repeat root canal treatment (re-treatment)


This patient had an infection in the gum above the upper left first molar tooth. This infection was causing a bad taste and some pain when biting. When looking at the gum above the tooth, the area was swollen (left image). After repeating the root-filling, the gum above the tooth healed really quickly (right image)








The reason this previously root filled tooth became infected again is because there was an extra 'hidden' nerve space within the tooth. This extra nerve space was blocked and not visible to the dentist who previously did the root filling. With the benefit of the magnification we work with (and knowing where to look) we were able to find this extra canal.


All the old root filling material was then taken out and the space inside the tooth sealed with a disinfectant in place. This disinfectant removes bacteria in the tooth which was causing the long standing infection.


The second stage of treatment was to check to see the tooth was healing properly and then place a new root filling.


The new root filling was placed to completely seal the space inside the tooth and a strong filling was then placed to seal the access hole in the centre of the tooth.


These x-rays show the root filling before treatment and after treatment. After treatment, the entire space within the tooth is now sealed which allows the infection to heal.


Once a root filling has been completed, the most likely way bacteria can get back in to infect a tooth again is through a crack or fracture in the tooth. To protect a tooth from a crack or fracture developing, we often recommend a crown is placed on the tooth. More information about how a crown can protect a root filled tooth can be read here.








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