If I had a root canal, why does my tooth still hurt?

This photo is an xray of teeth with root canal treatments, and sometimes they can still be sore after treatment.

There are a number of possible causes of pain after the completion of a root canal. After a root canal is completed, no living nerve tissue remains inside the tooth, but nerve endings remain in the ligaments that attach the tooth to the surrounding bone. These ligaments have nerve fiber associated with them that can feel pain. They are the source of any post root canal pain.

The possible causes of pain are numerous, and include inflammation of the tissues at the end of the tooth root after root canal. This inflammation may be due to extra filer in the root or irritation of the tissues during the root canal procedure. Sometimes the root canal files we use to clean out the tooth roots go slightly past the end of the tooth and can either inject some bacteria at the tip of the root or temporarily damage the ligaments. This inflammation usually resolves by itself given enough time.

Another source of post root canal discomfort is a high bite and this can easily be corrected by your dentist. If you bite down, with no food in your mouth and the root canaled tooth hurts, then the bite should be adjusted. Teeth undergoing root canals should be not be in a heavy bite.

Other possible causes of pain are a continued infection or a root fracture.  If a root canal is completed, but an infection still is present around the end of the tooth roots, a retreatment may be indicated especially if significant time has gone by without a resolution of the infection. Sometimes an infection can be caused by a fracture of the tooth in question and in that case the tooth usually has a hopeless prognosis and requires extraction.

It is also possible, but not as common that persistent pain exists due to a sensitization of a nerve ganglion  We have all heard of ‘phantom limb pain’. This a similar phenomenon. Some of these patients can have pain even after the offending tooth is removed. Again, this is quite a rare occurrence.

Dr. Andrea Stevens is a cosmetic and family dentist in practice in Kanata, Ontario. If you have dental questions, you can call her at 613-271-7091 or book an appointment online.