Why does my tooth hurt after root canal treatment?

October 15, 2015

This is a question that patients quite often ask, especially when they have few if
any symptoms of pain prior to the procedure.
However if the tooth has a non vital pulp (dead nerve) it should still be treated
otherwise it can become infected and cause an acute abscess at any time.
This is why the dentist may advise root canal treatment even if the patient has
no symptoms.
There are a number of possible causes of pain after the completion of a root
canal treatment. After the treatment is completed no living pulp tissue remains
inside the tooth, but nerve endings remain in the ligaments that attach the tooth
to the surrounding bone. These ligaments have nerve associated with them that
can feel pain. They are the source of any post root canal pain.

The possible causes of pain are numerous.
Inflammation of the periapical tissues after root canal treatment is one.
Periapical tissue is the tissue round the end of the root. This inflammation may
be due to extruded sealer or ‘over instrumentation’ during procedure.
Sometimes the root canal files go past the apical terminus and can either inject
some debris periapically or just 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 a dentist. If a patient bites down, with no food in their mouth
and their tooth which has had the treatment hurts, then the bite should be
adjusted. Teeth undergoing root canal treatment should be not be in a heavy

Other possible causes of pain are a persistent infection or a root fracture. If a
root canal treatment is completed, but an infection still is present around the
periapical area then 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.

With the exception of the above then pain following root canal treatment almost
resolves but it can take time.

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