Can You Do a Root Canal Through a Crown?

As a busy dentist in private practice, I get some variation of the “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.

Root Canals Get No Lovin’

Root Canal awareness week banner

Root Canal Awareness Week 2014. Logo courtesy AAE.

As we get ready to kick off the 8th annual Root Canal Awareness Week on Sunday March 30, it is remarkable to see that root canals are still perceived to be horribly painful and worse than torture. I outlined this myth in one of my Dental MythBuster posts called Dental MythBuster #3 – Root Canals Hurt!

Needless to say, despite that post getting over 12,000 views, the myth lives on in the popular media. Let’s see where:

  • The New York Times, February 7, 2014. “…taxes you pay on your investments has as much appeal as a root canal.”
  • The Los Angeles Times, June 14, 2009. “For the average American, modern air travel has all the appeal of a root canal.”
  • Northwest Indiana News, February 20, 2014. “… the topic of life insurance has about as much appeal as a root canal.”
  • The Los Angeles Times, March 29, 2011. “I had a root canal, and that was fun” (this was done in a sarcastic manner).
  • Washington’s Blog, August 26, 2013. “the American people would much rather get a root canal or a colonoscopy than bomb Syria.”

At least in the last example, the procedure is considered more desirable than a regional war and on on the same level as a colonoscopy!

And lastly, we have the President of the United States publicly maligning the procedure in his State of the Union Speech seen here:

So clearly, the procedure is believed to be unpleasant. But shouldn’t we all just stop worrying and appreciate root canals for what they do?

How I Learned to Stop Worrying and Love Root Canals

Dr. Strangelove who would not have worried about a root canal

Dr. Strangelove would have loved what a root canal could do (image courtesy wikipedia.org)

While there are different view on this borrowed line from Dr. Strangelove, there is no ambiguity when applied to the root canal procedure. This procedure helps to save teeth and prevents premature tooth loss.

Once you are adequately numb, you feel no pain during the procedure.

So let’s get this straight. You have a broken down tooth, one that you are at risk of losing. A procedure is available, one that does not hurt, that will allow you to save the tooth and not go around toothless!

And despite all the inherent benefits, the procedure is maligned by nearly everyone, including President Obama.

For this Root Canal Awareness week, let’s try to appreciate them. Or, to take inspiration from Stanley Kubrick’s film, let’s stop worrying and love root canals!