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

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.

Can a Dentist Save My Tooth Without a Post and Core?

I expected my dentist to tell me I needed a root canal, but he also mentioned adding a post and core. I did not fully understand her explanation about why I needed the post and score. It seemed that she was repeating something she had read in a textbook. I am anxious about a root canal, but a post and core sound like a long appointment. When are a post and care necessary? Thank you. Noah from Detroit, MI



Thank you for your question. Dr. Michalski would need to examine and x-ray your tooth for an accurate diagnosis, but we will explain the purpose of a post and core, when it is required, and how it affects the long-term outcome of a tooth.

What Are a Dental Post and Core?

A dental post and core are materials to strengthen a tooth weakened by decay, damage, and root canal treatment. The post is a small cylinder that supports a core. The core is a dental filling material that replaces the tooth pulp and supports a dental crown.

Why Would a Dentist Recommend a Post and Core?

Dental post in tooth in upper photo and a built up tooth lower photo
Post (upper photo) and tooth bulit up with core (lower photo_

A dentist may recommend a post and core so that your tooth can support a dental crown. Sometimes, preparing your tooth for a crown requires a dentist to remove a lot of decay or damage, leaving a small amount of tooth structure. The core, or dental filling material, will replace the tooth structure and allow a dentist to cement a crown on the tooth.

The process includes these steps:

  • Complete root canal therapy to remove tooth decay and infection
  • Place one or two posts into the tooth
  • Fill the tooth with dental material
  • Build up and shape the tooth with dental bonding
  • Bond a dental crown to the tooth

Will You Lose Your Tooth Without a Post and Core?

Declining a post and core may result in tooth loss for these reasons:

  • You may not have enough tooth structure to support a dental crown.
  • Your tooth can become weak and brittle.
  • Without a post and core, you may need an extraction and dental implant

Please keep in mind that if you lose the tooth, replacing it with a dental implant and crown can cost $3,000 to $5,000 depending on these factors:

  • Condition of surrounding gums and bones
  • Procedures you may need in preparation for an implant
  • Dental fees in your location in the U.S.

If you are unsure about your dentist’s recommendation for a post and core, schedule a second opinion with an advanced cosmetic dentist trained in root canal therapy and dental implants.


Dr. Thaddeus Michalski, a Rocky Hill, Connecticut dentist and Diplomate of the International Congress of Oral Implantologist, sponsors this post.