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Why Does My Root Canal Tooth Hurt After Weeks of Antibiotics?

Posted by AllSmiles

My second molar root canal tooth still hurts, although my dentist completed the root canal in August of this year. My dentist prescribed antibiotics twice, but the tooth still hurts. The pain is severe when I chew. Should I ask her for more antibiotics, or is something else wrong? Thank you. Anita from Dover, DE


Thank you for choosing our office for your question.

Although Dr. Michalski would need to examine your tooth and x-rays for an accurate diagnosis, we can explain what may be happening.

What Causes Continued Pain After Root Canal Therapy?

Diagram of the side of a skull with the TMJ jaw joint and ligament, dsik, condyle highlighted
Stress on a tooth can irritate the jaw joint

Causes of pain after root canal therapy may include these factors:

  • Untreated root canals – Sometimes, a tooth has multiple or curved channels. The condition will persist if your dentist misses canals or cannot clear the infection from curved canals.
  • Infection in another tooth – Pain from another infected tooth can refer to the root canal tooth.
  • Irritation and inflammation – Clearing infection from a tooth can irritate it, leaving it inflamed and sensitive. It can take several weeks for the sensitivity to fade. A dentist may make a thin custom mouth guard to wear and night and relieve the pressure on the inflamed tooth. Otherwise, continued stress on the tooth can lead to jaw pain, earaches, headaches, and other TMJ symptoms.
  • Irritation from crown preparation– Removing tooth structure to prepare the tooth for a dental crown can irritate it. The irritation should improve gradually.

Questions to Ask to Determine the Source of Discomfort

An accurate diagnosis includes asking you these questions:

  • Is your discomfort better, worse, or the same after root canal therapy?
  • Do you feel sensitivity to heat or cold in the tooth?
  • Other than chewing, what triggers the pain?

Ask your dentist for an x-ray to ensure she cleaned the infection from all the canals. If canals are challenging to detect or reach, your dentist must refer you to an endodontist (root canal specialist) for further treatment. Specialists have tools designed to reach challenging canals.


Rocky Hill, Connecticut dentist Dr. Thaddeus Michalski, sponsors this post.