Missed Nerve

It is possible that a nerve canal can be missed during a root canal and not be treated, and it is important to look for this possibility.

We recently had a patient come to our Bartlesville Dentist office complaining of swelling and pain in the gum surrounding a tooth that was treated with a root canal several decades earlier. For the majority of that time he had no problems with the tooth in question except that it was discolored. In an attempt to improve the color of the tooth, his previous dentist carried out what is called an internal bleaching. This procedure involves drilling into the tooth and bleaching it from the inside. The process was successful, but an unfortunate side affect was that the patient began to experience pain in the tooth. This was accompanied by firm swelling in the surrounding gums. For these symptoms, he was referred to an oral surgeon who then removed the infected cyst. The swelling eventually returned, because the oral surgeon failed to treat the cause of the cyst.

This patient then came to me for an evaluation. Upon X-ray, I realized that the original root canal had been performed fine, but I was able to see the characteristic black circle of an abscess at the tip of his root. I thought we should attempt to re-treat his root canal to see if we could cure the infection that was now causing his symptoms. Otherwise, the root tip would need surgical removal.

Re-treatment of a root canal involves removal of the old rubbery filling inside the root, followed by reshaping of the root, disinfection, and then refilling. Another possibility is that a nerve canal was missed during his original root canal and was thus not treated. This problem is often not distinguishable on X-ray because x-rays are a 2-dimension representation of a 3-dimensional object and this can often be obscured. A missed nerve canal during such a procedure is the primary reason that a tooth that has undergone a root-canal can become re-infected.

We did, in fact, find such a nerve canal -- one that had been missed during the initial root canal. I carried out root canal therapy on the previously missed canal, and found that this did indeed clear up his infection. The lesson to be learned is that although properly performed root canal therapy is usually about a 90% success rate, problems still can occur, and a missed nerve canal can often be the cause of re-infection.