Cosmetic Dentistry Blog Cosmetic and General Dentistry Questions Answered

September 22, 2018

A crown or a veneer on a front root canal tooth?


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Hello Doctor Hall. About 2 years ago I had a root canal on a front tooth. I had a general dentist do the root canal. It wasn’t painful and I was very happy. He wanted to put a veneer on the tooth for a very low price. But, I decided not to do the restoration at that time.

I didn’t realize that lack of blood flow to the tooth would make it change color and about a year ago it started to change. I eventually had a porcelain crown put on by another general dentist. She filed down the tooth to a small fang and it really bothered me at the time. So far, the crown is stable. But I know these things don’t last forever. I just want to know if I was duped by the second dentist who did the crown rather than a veneer? Thank you for your time.
Gary from Florida

Gary,
I have a couple of points in response to your question.

First, about the choice of a crown versus a veneer. The simple answer that is taught in dental school to the question, “How do we restore a tooth after a root canal treatment?” is, “Do a crown.” Dental schools really don’t get into doing veneers much. So I wouldn’t say that the second dentist “duped” you—she just did what she was probably taught. But yes, it can be unsettling to have your front tooth ground down to a stub in preparation for a crown.

Here’s the explanation for that. Most teeth, when they need a root canal treatment, have an extensive amount of tooth structure missing and they really need a crown. I take it, from your initial decision to not do a restoration, that your tooth did not have extensive decay or a large break. Maybe it was just bumped in an accident. Also, after a root canal, a tooth tends to become more brittle and subject to fracture. A crown helps protect against fracture of the tooth.

But there is a difference here in the needs between a front tooth and a back tooth. Back teeth have chewing surfaces and cusps, and when you bite down, the pressure on the cusps tends to push them apart. Thus, when a back tooth breaks, it will likely split between the cusps. A crown will prevent that type of break.

Front teeth are subject to different stresses. There is no chewing surface, and the stress on a front tooth is almost all lateral. When you bite together, the lower front teeth push forward on the uppers, and the upper front teeth push backward on the lowers. Also, if you get hit in the face, the impact on the upper front teeth will be a lateral impact. Thus the most likely break of a front root canal tooth is snapping off at the gumline. A crown preparation, which will involve taking off about a millimeter of tooth structure all the way around, will actually weaken a tooth against this type of stress.

Here is a photograph of a crown preparation for a front tooth. This is a very conservative preparation. Most dentists will be more aggressive than this in removing tooth structure. But even with this conservative preparation, you can see that the natural tooth is going to be much stronger in resisting breaking off because of the thicker neck of the tooth.

photograph of a smile, showing the patient's left front tooth ground down and prepared for a crown

A veneer would leave the tooth much stronger. To prepare a tooth for a porcelain veneer, a dentist has to only remove about half a millimeter of enamel, and from the front of the tooth only. Below is a photograph of two front teeth prepared for porcelain veneers.
two front teeth, prepared for porcelain veneers, showing about half a millimeter of enamel removed

So why don’t most general dentists do veneers on front root canal teeth? With a much thinner layer of porcelain, it requires more skill on the part of both the dentist and the laboratory technician to block out the darker color of the underlying tooth. Most general dentists really don’t know how to do that.

Moving on from that point, I also wanted to make a comment about the discoloration of the tooth. It isn’t widely known that the source of the vast majority of the discoloration of a front root canal tooth is not the tooth drying out, but it comes from the root canal filling materials that are used inside the tooth. When I did a root canal treatment on a front tooth, I would clean out all the root canal filling materials from the inside of the crown of the tooth, place a white fiberglass post down into the root to strengthen the tooth, and then seal the opening I had made into the tooth using composite filling material. With that type of treatment, it could be five or ten years before any discoloration would set in and the tooth would need a veneer.

– Dr. Hall

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About David A. Hall

Dr. David Hall was one of the first 40 accredited cosmetic dentists in the world. He practiced cosmetic dentistry in Iowa, and in 1990 earned his accreditation with the American Academy of Cosmetic Dentistry. He is now president of Infinity Dental Web, a company in Mesa, Arizona that does complete Internet marketing for dentists.

August 31, 2017

After my porcelain veneers, I need root canal treatments


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Dear Dr. Hall,
I had full mouth smile makeover done (veneer crowns) in January 2017, 12 upper teeth and 10 lower teeth. After they put permanent crowns on, I felt sharp pain on teeth #5 and #13 (upper second premolars). The dentist did crown height adjustment 3-5 times, finally the pain went away, but tooth abscesses formed on top of both #5 and #13 teeth within 4-6 weeks. The dentist x-rayed and said the teeth nerves had died, and I need root canals. I was upset and didn’t realize that nerve damage could be a risk involved in veneer crowns. I remembered I asked if there is any risk doing smile makeover during consultation, I was told there is no risk. The X-ray showed that my teeth nerve are fine before the procedure. I am confused and don’t understand what is going on.

The dentist said he didn’t know why, it rarely happened, I am the unlucky one. He referred me to an endodontist to perform the root canal procedure, and the endodontist found more teeth showing no response to cold test, also my gum flared up, swollen and very painful. So far I have had root canals done on 4 teeth (#4, #5, #13, #14), and #12 needs a root canal too, just matter of time. The tooth #3 starts feel strange too. Dr. did agree to pay half of the cost of the 4 root canals, but I am worried it will be an ongoing nightmare. What if the crowned teeth one by one goes bad over the time? I am very frustrated and feel misled. It not only financially cost me, but also add lots of stress on me. Please tell me what i should do and I need some advice. Thanks!
Sincerely,
Jenny from Texas

Jenny,
To answer your question, I first need to lay down some terminology so we’re clear in what we’re talking about. I’m a big fan of clarity in communication, which requires precisely defining what words mean.

two front teeth, prepared for porcelain veneers

Porcelain Veneer Preparation

You’re saying you had “veneer crowns.” But a porcelain veneer is one thing and a porcelain crown is something very different. A porcelain veneer requires very light shaving of the front surfaces of the teeth—sometimes no shaving at all is required. I found this photograph that illustrates a typical porcelain veneer preparation. Maybe half a millimeter of tooth structure has been shaved off, and the porcelain will be bonded over this.

two front teeth, prepared for porcelain crowns

Porcelain Crown Preparation

This second photograph shows a typical porcelain crown preparation for the same two front teeth. Much more tooth structure has been removed.

It appears from your description that what you had done were porcelain crowns, not porcelain veneers. It is very rare that a porcelain veneer preparation on a tooth will end up making it need a root canal treatment. But a crown preparation will go much deeper into the tooth, increasing the risk of a pulp exposure, resulting in an infection of the pulp and the need for a root canal treatment.

A smile makeover, by itself, does not require any aggressive grinding down of the teeth, which is what must have been done in your case. If your teeth had large fillings or decay before getting your makeover, then grinding them down was necessary. If that is the case, it wouldn’t be surprising if some of those teeth ended up needing root canal treatments. Anytime there is a lot of decay or large old fillings, there is a risk of teeth getting infected. But I would call that procedure a full-mouth reconstruction, not a smile makeover.

But if this that you’re calling a smile makeover was just for aesthetic reasons, then your dentist was much more aggressive than he needed to be, and I believe he should be responsible for the cost of the damages he caused. If you weren’t told of any of these risks up front, he is especially vulnerable.

A smile makeover should be done with porcelain veneers whenever possible, to avoid problems like you are having. There is even a trend in recent years for excellent cosmetic dentists to place what are called ultra-thin porcelain veneers, which require even less preparation than is shown in the photograph above. Some even try to do the makeover without preparing the teeth at all. But many dentists who aren’t expert in cosmetic dentistry simply don’t know how to do porcelain veneers very well, and so they resort to full coverage crowns. Porcelain veneers aren’t taught in dental schools—they’re a cosmetic procedure for which a dentist should get post-graduate education.

As far as what you should do now, I don’t know what to tell you. You don’t really have any option, if you want to save these teeth, besides having the root canal treatments done. And it’s curious that your dentist is offering to pay half the cost of the root canal treatments. This seems to indicate that he is feeling some guilt over this. If that’s the case, I would press him to pay the whole thing.

About what to expect long term, it’s hard for me to tell for sure from here. My guess would be that any teeth that end up having problems, you will find out within the first few months and then things will stabilize.

Dr. Hall

Do you have a comment or a question or anything else to add? We’d love to hear from you. Enter your comment below.

Click here to ask Dr. Hall a question of your own.

About David A. Hall

Dr. David Hall was one of the first 40 accredited cosmetic dentists in the world. He practiced cosmetic dentistry in Iowa, and in 1990 earned his accreditation with the American Academy of Cosmetic Dentistry. He is now president of Infinity Dental Web, a company in Mesa, Arizona that does complete Internet marketing for dentists.

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