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Getting a Root Canal Through a Zirconia Crown

A root canal can be done through a zirconia crown meaning you don't have to remove the cap prior to getting your procedure done. Now, whether you need a new crown afterwards would depend on a couple of factors.


Root canal through crown that got filled afterwards
Root canal through crown that got filled afterwards


Table of contents:


Can you get a root canal through a zirconia crown?

Of course you can get a root canal straight through your zirconia crown and we see this in clinical practice on a daily basis. It is quite easy to spot these because you'll see a zirconia crown with a filling on the occlusal surface.


Zirconia crown with hole drilled through top for root canal access
Zirconia crown with hole drilled through top for root canal access

The reason there is a dental filling there is because someone drilled through the top of it and repaired it afterwards. Then if you look on the x-ray, you'll see evidence of a root canal being done. Therefore it is certainly more than possible to get this done, it's just that having the crown on does make the procedure more difficult.


Root canal through crown - before and after x-rays
Before and after x-rays of root canal through a crown

Increased difficulty and complexity

Your dentist can drill through anything they want, enamel, dentin, fillings, and crowns. The only caveat with trying to do the root canal while the tooth has a zirconia crown on it is that it makes it more difficult. The ceramic material throws off the apex locator's reading in finding the working length.


working length of tooth diagram
Credit: Garg Nisha, Garg Amit

The purpose of a root canal is to remove the tooth's nerve but there are steps which need to be completed before it can be done.


Root canal steps:

  1. Create an access opening. Drill a hole through the top of the tooth until it reaches the pulp chamber. This is how you create an access to the nerve.

  2. Measure working length. Before your dentist can remove the nerve and clean out the canal, they must measure the working length (WL). The WL is basically the distance from the occlusal surface (chewing surface) to the tip of the root. Having a measurement ensures that you clean out the tooth from tip to tip. If your working length is short, you may be leaving a portion of the infection behind.

  3. Remove tooth nerve. Once you've the WL you can finally clean out the tooth!


The issue with working through zirconia is that the apex locator which is used to find the WL gives off errors whenever it touches the ceramic. The zirconium dioxide conducts some of the electrical currents and that results in a false reading. In order to get an accurate reading, you must prevent the file which is attached to the locator from touching the ceramic.



Do you need a new crown afterwards?

A frequently asked question is if you need a new crown after doing a root canal through it. The answer is that it depends on a couple of factors. You may be able to keep your old one and put a dental filling in it or you may need to replace it with a new zirconia crown.


Nonetheless, when in doubt the best thing to do is to get a new one but we understand that cost is a factor in the decision making process. Therefore, we'll try to give you some guidance as to when you may be able to salvage your old tooth cap.


Factors to consider if you need a new crown:

  • How old is it?

  • How big is the access opening?

  • Is tooth decay present?

  • Are finances a consideration?


When did you get that zirconia crown done?

An important factor to consider is how long you've had that crown. Is it brand new or has it been in your mouth for a decade already?

  • New. If you've only recently had the crown done then that would be a reason to not replace it. The chances of it being defective or decayed are fairly low.

  • Old. If you've had it for a long time now, perhaps it is time to get a new one. After all, nothing lasts forever except diamonds right? After a few years, sometimes the color is off or maybe there are chips on the porcelain. Those are all good reasons to have it replaced.


Is the root canal hole big or small?

In order to do a root canal through it, a hole must be drilled through the top of the crown. Was the root canal specialist able to make a small hole or was a big one required?

  • Small hole. A small access opening would mean that most of the structural integrity of the restoration should be intact. The smaller it is the better the prognosis.

  • Big hole. If a big access opening was required it may be better to get a new crown. There is a greater likelihood of the structural integrity being compromised from a large hole.


Is there a cavity underneath the crown?

Sometimes during the root canal, undetected decay can be found. If that is the case it would be prudent to remove the entire crown in order to see what else is going on in there. The presence of decay means that there could be more elsewhere underneath the cap.


It is impossible to visualize the entire tooth underneath simply through the access opening of a root canal. In this case, it would be best to take it off and get a new one once it's all done.


Is money an issue?

If you never budgeted for emergency medical treatment then our recommendation would be to take the three factors above into your decision. However if money is no issue, the best thing to do would be to get a new zirconia crown.


It's a no brainer that a fully intact crown is more structurally sound than one with a hole through the top of it. Even though it is filled back in with a composite resin, that access opening does decrease the prognosis.


Takeaway

Yes, it is possible to do a root canal through a tooth with a zirconia crown on it. It does make the procedure a bit more difficult but your dentist can still work around it.


The tough part is deciding what to do afterwards such as whether or not you should replace the crown. We've provided a couple of factors to take into consideration in making the decision but you can always discuss with your dentist.


If you need a brand new zirconia crown, the process would be a repeat of what you had to do the first time. If you're in long island city and need a new dental crown, our dentists can help you.

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About the author: Dr David Chen, DDS

Hello, I'm Dr Chen and I'm an actively practicing dentist in Long Island City, NY. I graduated from Columbia University College of Dental Medicine in 2016 but prior to going to dental school I was already working in the dental field. It's been more than a decade since I first got to know dentistry and let me tell you, time flies by quickly. Since then I've developed a fondness for writing, which is how this all got started!

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Medical Disclaimer:

This blog is purely meant for information purposes and should not be used as medical advice. Each situation in your mouth is unique and complex. It is not possible to give advice nor diagnose any oral conditions based on text nor virtual consultations. The best thing to do is to go in person to see your dentist for an examination and consultation so that you can receive the best care possible.

The purpose of all of this oral health information is to encourage you to see your dentist and to inform you of what you may expect during your visit. Due to the unfortunate nature of dentistry, there isn't really any true home remedies that will get rid of dental problems. Roughly 99.99% of them require in-person intervention by a healthcare professional.

Hint: That is the reason why you can't eliminate seeing dentists in your life!

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