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.

90 Second Wisdom Tooth Extraction Video

This post, featuring an HD video of a wisdom tooth extraction, is different from many previous posts. Instead of tackling a topic and answering questions via the written word, this post uses a YouTube video to answer questions regarding one of the more feared and dreaded procedures in all of dentistry: wisdom teeth removal.

This video was shot in my office and features a young, early 20s patient having a lower right impacted wisdom tooth removed under IV sedation. The third molar and sedation procedures are performed by me along with two assistants. Check it out here:

Having participated in the filming of dental procedures before, I will tell you that capturing high quality video footage is not easy. Camera angle, proper lighting, patient participation, etc. are all difficult to control. I can confidently say that this is very high quality video footage of a third molar extraction (click here to go directly to the video on YouTube).

This video does answer many questions and resolve many myths that I’ve seen in blog comments and in questions I’ve received over years of private practice. Let’s review them.

Does getting a wisdom tooth extracted hurt?
  • No. In the YouTube video, the patient was given local anesthesia (a.k.a. novocaine) beforehand. She does not flinch nor respond during the procedure. That is because she is numb and is also under twilight sedation.
Does the dentist have to put a knee on my chest to pull the tooth?
  • No. That is a popular myth that I debunked in this post. Extraction of a tooth requires the controlled, precise application of force. It rarely requires a pulling force. The tooth literally slides up and out of the socket – as you can see at the 2:00 mark of the video.
Will I be in pain for days after getting my wisdom tooth out?
  • Not necessarily. Each and every case is different. In this video, the extraction itself only took 90 seconds. So she had very little pain afterwards. Other third molars require more time and are more invasive. Those will likely be more painful afterwards.
What is an impacted tooth?
  • An impacted tooth is when bone, gums, and/or other structures prevent the tooth from coming into the mouth properly. Wisdom teeth are frequently impacted. In the YouTubevideo, we see a soft tissue impacted tooth, meaning that there was a flap of gum tissue preventing the tooth from coming in properly. Other teeth are considered bony impactions in which there is bone preventing the tooth from coming in completely. Bony impaction extractions are typically more invasive.

I hope you enjoyed the video and it helped to answer questions and dispel some myths. Comments are welcome.

I Passed Out at the Dentist. Why?

As a full time general dentist in private practice, I’ve seen patients faint more than once. And as a dental blogger, I’ve seen all types of comments and questions on this site about patients passing out. In fact, most people mistakenly assume that when something like this happens, it is because they are allergic to something the dentist used. In nearly all cases, that is an incorrect conclusion.

So, why is it that some people faint and/or pass out at the dentist? And what causes it?

Common Medical Emergencies in Dental Offices

In a widely cited survey, the number one emergency seen in a dental office is fainting – or more appropriately called syncope (sources: here and here). In fact, in one study, syncope accounted for 53% of all emergencies in a dental office (source: here). The second most common emergency is hyperventilation.

fainting at the dentist is not treated as an allergic reaction

Many mistakenly assume that fainting at the dentist is due to an allergic reaction.

To many individuals who’ve had adverse reactions at the dentist, this fact can come as quite a surprise. The scenarios that most patients believe are occurring – usually acute allergic reactions as well as cardiac events – very rarely occur.

Fainting vs. Passing Out vs. Vasovagal Syncope

Generally speaking, the above three terms are all roughly the same, with the term vasovagal syncope being the medically appropriate one. It can be defined as a temporary loss of consciousness due to a decrease in blood flow to the brain.

dental needle fear can cause fainting or passing out.

This is the most common trigger for an episode in a dental office.

Your brain is in constant need of oxygen. If blood flow to the brain is temporarily diminished, you are no longer able to function, and you lose consciousness. If this happens, it most often results in you falling to the floor, which then puts your head at the same level as your heart. This change in position, along with the removal of the stimulus which caused the episode (more on this later), then allows for adequate blood to flow to your brain, and you very quickly regain consciousness.

In vasovagal syncope, a trigger (such as the sight of a needle) will cause a susceptible individual’s nervous system to over-react and cause certain physiologic changes which can lead to the decrease in blood flow to the brain.

Common Triggers of Vasovagal Syncope in a Dental Office

dental drill can cause you to pass out or faint

The dental handpiece or “drill” can cause some to pass out.

A dental office is a unique setting in that the patients walking through the door typically don’t want to be in the office, but they know they have to. This is why passing out episodes occur quite frequently. The most common triggers seen in a dental office include:

  • The sight of the needle (this is the number 1 trigger).
  • The slight sting of the dental injection.
  • The sight of blood.
  • The smell of an office.
  • The high pitched squeal of the dental handpiece.
  • And others.

So, if a trigger is experienced by a susceptible individual, the syncope episode can commence.

A Typical Fainting Episode at the Dentist

Each and every episode of passing out is unique, as is every patient. The following is a classic example of what someone might experience in a vasovagal syncopal episode at the dentist.

  • You don’t like coming to the dentist but you know you have to get a filling. You have been dreading it for over a week.
  • You are called in from the reception area. While walking in, you see a needle that looks large and intimidating.
  • The dentist comes in and says hello. At this point, you’re still thinking about the needle, and you begin to feel somewhat lightheaded.
  • You hear the dentist talking to the assistant but their voices seem muffled. You notice that you are breaking out into a sweat, even though the temperature was perfect just a couple of minutes earlier.
  • You begin to have a feeling of nausea and your thoughts appear fuzzy. Your muscles suddenly feel incredibly weak and you don’t even think you could lift your hand. You attempt to say something but you can’t muster the strength or thoughts to put words together.
  • Your vision appears compromised, first by seeing bright lights, and then with black or cloudy vision. You are sitting upright but all you want to do is lie down…

Next thing you know, the chair is completely reclined and you are lying horizontally in it. The dentist and the assistant are sitting next to you. The dentist is looking at you intently and is feeling your pulse on your wrist. He/she notices you waking up and says:

“Well, it looks like you fainted for a bit. Don’t worry. It happens more often than you think. We’ll keep you reclined for a couple of more minutes and then we’ll slowly bring the chair up.”

Final Thoughts

If this is anything like similar posts, this will generate a lot of traffic and comments. Please consider reading other posts I have on similar topics. If you think you’re allergic to novocaine, you should read this three part series (one, two, and three). If you think you’re allergic to epinephrine, you need to read this and this. If you’ve had difficulty getting numb, check out this post and this post. Enjoy!

 

Long Term Opioid Use and Dental Local Anesthesia

Norco opioid pain medication used by dentists

Norco – a common opioid pain medication

As a dentist in a busy private practice, I am constantly doing dentistry, which involves injections of local anesthesia. I have blogged previously about certain circumstances in which it can be difficult to get a patient numb (those are located here and here). But an increasingly common phenomenon involves difficulty in getting patients numb who are long time users of opioids (often called narcotics).

A common situation is a patient with chronic pain who has been taking an opioid type painkiller long term (such as Percocet, Oxycodone, Oxycontin, etc.). A dental procedure that requires effective local anesthesia is attempted on that patient. During the procedure, it is learned rather quickly that the patient is having difficulty either getting numb and/or staying numb.

Opioids, Narcotics, Pain Pills, Etc.

The term opioid is derived from the word opium, which is a component of the opium poppy. The raw opium can be processed to produce morphine or heroin – both of which are powerful pain relievers. The term opioid simply means a medication that acts on the opioid receptor.

Opium poppy, the basis for narcotics

The opium poppy – the flower from which morphine and heroin are derived. Image courtesy wikipedia.

Millions of Americans take opioids for both acute and chronic pain. For those individuals who take them chronic pain, a tolerance will develop, requiring larger doses. Large doses of opioids taken over time can lead to many long term effects. Many of those effects – constipation, dry mouth, etc. – are well documented. What is not well documented nor well researched is how long term use impacts the effectiveness of local anesthesia.

Long Term Opioid Use and Dental Local Anesthesia

Unfortunately, there is very little “official” information available for practicing dentists and dental students on which to rely. The most widely read and cited textbook on local anesthesia for dentists – A Handbook of Local Anesthesia – by Dr. Stanley Malamed – makes no mention of this phenomenon.

Lidocaine is less effective in opioid users.

Multiple studies have shown lidocaine is less effective in opioid users.

However, a survey of recent research has shown multiple articles which directly and/or indirectly give support to this phenomenon:

  • In this article, opium abusers were compared to non-abusers in their response to lidocaine (lidocaine has replaced novocaine as the local anesthetic of choice in dentistry). The abusers were found to require a longer amount of time for the lidocaine to work. And in addition, a greater amount of lidocaine was required.
  • In this study involving rats, the administration of morphine (an opioid) resulted in a decrease in the potency of lidocaine.
  • In another study involving opium vs. non opium users, chronic users experienced a shorter duration of local anesthesia than non users.

In fact, there is a specific term for a related phenomenon, which is Opioid Induced Hyperalgesia. Basically, those individuals who are chronic users can become MORE sensitive to painful stimuli.

However, despite all of these studies, there remains to be seen a widely accepted theory for a mechanism behind the local anesthesia resistance seen in these individuals.

What This Means for Dental Patients

As with most dental issues and concerns, the most important thing is to make sure your dentist is aware of your history. This can and should include any history of any and all use of prescribed and recreational drug use.

Will it be possible for you to get completely numb? There is no way to know for sure – each and every person is unique. However, if your dentist is aware of your history, then it is much more likely that the best approach(es) can be taken.