Can You Do a Root Canal Through a Crown?

As a busy dentist in private practice, I get some variation of theĀ “can I get a root canal on a tooth with a crown” question quite frequently. The question comes in various forms, but the general summary is something like this:

“I got a crown done about three years ago. Everything was fine until a week ago, and now it feels like it is on fire. I think I need a root canal. Can you do a root canal through a crown?”

The answer to this question is yes (most of the time).

Why Teeth Need Root Canals

Before we describe why/how a root canal is done through a crown, it is important to know why teeth sometimes need root canals.

tooth with cavity needing a root canal

This tooth had a large cavity. The brown spot visible in the photo is the decay. On subsequent removal of the decay, the nerve became inflamed, and the tooth needed a root canal.

A tooth needs a root canal when the nerve inside the tooth becomes inflamed or infected. This can be due to several reasons, including:

  1. Dental decay (a.k.a. cavity) that either comes close to or enters the nerve of the tooth.
  2. A crack or fracture of the tooth where the nerve become exposed.
  3. A large restoration (filling) placed very close to the nerve. The filling is done due to the presence of decay and/or cracks (as talked about in points 1 and 2 above). Note it is not the filling that causes the need for the root canal, but rather the decay and/or fracture.
  4. Trauma to a tooth in which the nerve is injured.
  5. Other more infrequent causes (internal resorption, external resorption, jaw cysts, metastatic malignancies which enter the jawbone, etc.)

Generally speaking, reasons 1, 2, and 3 are the causes for 99% of all root canals.

What is a Root Canal?

Describing a root canal is not the point of this post. But a general summary can be presented.

Root canal access cavity

View of a cleaned out nerve chamber of a lower tooth as seen from directly above the chewing surface. The 3 holes are entry points to 3 separate canls.

In a root canal, the infected and/or inflamed nerve tissue inside the tooth is cleaned out and then filled with a special filling material. We do this by drilling a hole from the top of the chewing surface of the tooth into the nerve chamber. In the photo above, you can see the large hole in the tooth which leads down and exposes 3 smaller openings or orifices. These are the openings to the canals of the tooth.

In a root canal, the roots of the tooth remain. They are not removed. By having a root canal done, you are able to keep a tooth that might otherwise have to be extracted.

How a Root Canal is Done Through a Crown

A crown, often called a cap, is a custom fabricated restoration comprised of metal and/or ceramic that covers the top of portion of the tooth. Crowns are done for many reasons, but they are mostly done to protect a tooth that has been compromised by decay and/or fractures.

When a tooth with a crown needs a root canal, you can expect the following sequence:

  1. You will be given local anesthetic so that your tooth is totally numb (and other parts of your mouth too).
  2. A rubber dam will be placed over the tooth.
  3. A small hole will be drilled through the crown into the tooth and into the nerve chamber.
  4. Then the dentist is ready to begin cleaning out the infected and/or inflammed nerve.

Before and after photos showing a root canal through a crown. In the left photo, you see the procedure in process with the rubber dam and access into the nerve chamber. The right photo shows the completed procedure with a filling sealing the access hole. The crown is saved! Photos and dentistry Dr. Nicholas Calcaterra.

In nearly all cases, the root canal is done through the crown, the access is sealed, and then everything goes back to normal.

When Saving the Crown is not Possible

In some cases, doing a root canal through a crown and keeping that crown is not possible. This can happen for a variety of reasons. Some of them include:

  • The decay – which caused the need for a root canal – is so advanced that a new crown is needed.
  • A large piece of porcelain broke off during the procedure so that the crown is no longer functional.
  • A root fracture of the tooth was discovered during the procedure and the tooth must be extracted.

The above list is not comprehensive but covers many of these situations.

In all cases, your dentist or endodontist should discuss with you the likelihood of you keeping the same crown after the root canal procedure.

Comments

  1. Nicholas Alexander says:

    Dear Dr. Calcaterra,

    Does mouthwash, in addition to daily brushing and flossing, and regular teeth cleanings by a hygienist, contribute significantly to combating tooth decay and the like?

    If the answer is affirmative, what sort of mouthwash should one use?

    Thank you for your previous answers to my questions. They have been helpful.

    Regards,

    Nick
    Sacramento, CA

    • Mouthwash is proven to be effective when used in addition to brushing and flossing.

      Generally speaking, there are two major types of mouthwashes. Those that help the gums – like fighting gingivitis – and those that combat decay. So the type of dental problems you have, if any, should dictate what type of mouthwash you use. For example, if you are prone to decay, a high fluoride toothpaste such as ACT would be helpful.

      Dental Hygienists are very good at analyzing your needs and making recommendations on mouthwash.

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