Why Do Some Root Canals have to be Retreated?

We know root canals give some of you the heebie-jeebies.  Many people are afraid of root canals.  The thought that they don’t last forever and require more treatment can be upsetting.  Here, we aim to explain why it can be necessary to re-enter a root canal and make repairs.

Brief Explanation of Root Canals

In case you are wondering, a root canal (officially termed a root canal treatment or RCT) removes the soft tissue containing nerves and blood vessels from the internal space within a tooth.  All teeth are hollow, and the hollow chamber contains something called the pulp.  Dentists often use the word pulp and nerve interchangeably, so don’t let that confuse you.  When the pulp becomes infected due to a large cavity or injury, it must be removed.  Antibiotics cannot fight an infection when it is within the internal chamber of a tooth.  Removal is the only option.

A root canal treatment removes all of the pulp tissue, kills any bacteria living inside the tooth, and seals it with a biocompatible filling material that extends down the entire length of each root.  (Some teeth have three to four roots, and each root requires the same treatment.)

Why They “Fail”

There are several different reasons that a root canal could fail.  Basically, a failure means that bacteria has penetrated the seal created by the original root canal.  The different reasons for failure are the different ways that bacteria can infiltrate the root system.

  1. Bacteria remained within the tooth during the original root canal treatment.

Tooth roots are complicated, and often there are tiny accessory canals that do not show up on x-rays and can hide bacteria.  This is relatively rare, but possible.

  1. Bacteria penetrated through new decay that developed on the outer tooth.

Unfortunately, this is much more common.  The outer portion of the tooth is typically covered with a dental crown.  When decay recurs at the edge of that crown, it is simple for bacteria to work under the crown and reach the root canal.

  1. Bacteria seeped through a crack in the tooth.

Also common, a crack in either the outer portion of a tooth or in the tooth’s roots will allow bacteria to enter the tooth.  Cracks are very difficult to diagnose and even more difficult to treat.  This is usually the cause of “unexplained” failures of root canals.  It may not be clear that this was the cause until the dentist extracts the tooth and can see the crack running down the length of one of the roots.

What a Retreatment Does

A retreatment of a root canal removes the original filling and starts over.  The dentist cleans the internal chamber and the walls lining the inside of the roots, removing any new or leftover bacteria.  Then he or she reseals each canal with a new filling material.

Sometimes, during the retreatment process, the dentist is able to see the exact cause of failure, like a visible crack.  In other cases, the cause of failure remains a mystery.

Why Retreatments are Necessary

A retreatment is necessary when a tooth that has already had a root canal treatment gets a new infection.  What is tricky about these is that patients are often unaware of the new infection.  The original root canal removed all the nerves from within the tooth, so the tooth cannot “tell you” when something is wrong.  Your dentist is able to spot a new infection by taking yearly x-rays to monitor the health of an existing root canal.  Don’t skip these yearly exams.  They are vital to catching dangerous infections before you have any noteworthy symptoms.  The sooner you catch it, the more successful your retreatment will be.

More Questions about Root Canals?

Call 940-382-1750 today to schedule a consultation with Dr. Chowning.  He will evaluate any existing root canals and help you monitor their success as time passes.  Our goal is always to anticipate and prevent any potential dental problems.

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