Cosmetic Dentistry Blog Cosmetic and General Dentistry Questions Answered

March 11, 2014

Repairing a porcelain crown

Dr. Hall,
My son has his four front teeth capped with the caps that have a white color in the front and the silver on the back. One of the crown is chipping revealing the silver under the white front. No dentist in or around town says they can help me without replacing the crown. Is there anything that can be done to simply make the front all white again without replacing the whole crown?

– Bobbi from New Mexico

Bobbi,
I have a couple of things to say about your son’s situation.

Yes, there is a way to repair a crown that is chipping and showing the underlying metal, but you’re going to need to go to a dentist with particular expertise in cosmetic dentistry and bonding technology. In Las Cruces that would be Dr. Brian Gilbert. Do a Google search for “Bright Star Dental” and you’ll find him. Over 95% of dentists are not going to know how to do this or have the equipment needed to do this.

The process is very similar to the technique I wrote about several years ago for repairing a porcelain bridge. The underlying metal has to be etched with a small sand blaster and then treated with a metal bonding agent like Panavia. The fractured edges of the porcelain have to also be etched either with the same sand blaster or hydrofluoric acid or both and then my preference is to treat it with a silane coupling agent. Then the metal has to be coated with an opaquer. The crown is then ready for bonding with composite restoratives, to match the color and surface luster of the porcelain.

But there is more to this situation than just repairing the crown. The question that comes to my mind is, Why is this crown chipping? You are writing on behalf of your son, which suggests to me that he is still young, meaning these crowns haven’t been on him for that long. The crowns are porcelain fused to metal, which is pretty strong. When they chip, it is usually because of some flaw in the making of the crown. And you say, “is chipping.” I’m going on sketchy details from you here, but your putting it that way suggests that this is a process that is occurring over time, not a single event. Is it going to chip some more? Something is either wrong with this crown, that it would do this, or there is something happening with your son that is particularly abusive to this crown.

And then I have the question, why were porcelain fused to metal crowns placed on your son’s front teeth in the first place? Dentists who care much about the appearance of their work will put all-porcelain crowns on front teeth almost exclusively, not porcelain fused to metal. I’m really questioning the dentist who did this work.

I’m admitting that my advice here is based on my trying to fill in the blanks with things that you haven’t told me explicitly. If I am filling in the blanks correctly, then here is what I would advise doing. First, I would go back to the dentist who did this and see if he or she will make this right by replacing this one crown for free. If that doesn’t work, then I would go to Dr. Gilbert and have him repair the crown. Then, when your son is college age, if he isn’t that age yet, I would replace all of these crowns with natural-looking all-porcelain crowns.

I’d be interested in hearing more about your case, if you care to write back.
– 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.

March 11, 2013

Porcelain fused to metal crowns are ugly on front teeth. Why would a dentist do this?

Dr. Hall,
I had 4-front teeth crowned with porcelain over metal. I am VERY upset because I was not informed about the dark line that I now see?? I did go to dentist today & he is replacing 1-tooth w/ dark line, but after just a month of having these crowns, I noticed on the back of THIS PARTICULAR TOOTH a spot of METAL appeared. I think that is why he is replacing it. Is this a rare problem?? I wish that I had known my options!!?? How much does a crown w/ porcelain over metal cost?? I am in a small town near Tampa! I paid about $989 per crown; is that too much?
– Shirley from Tampa

Shirley,
Back in the early 1980s, putting porcelain fused to metal crowns on front teeth was a good idea. But not in 2013. There are now porcelain bonding techniques where porcelain can be bonded directly to the tooth instead of having to be bonded to a metal framework to give it strength. And there are new high-strength ceramics. So there is no longer any need for the metal foundation. All-ceramic crowns are plenty strong enough to serve just fine on front teeth.

In my opinion, a dentist who is serious about the appearance of his or her dental work wouldn’t even dream of putting a porcelain fused to metal crown on a front tooth. Not only does the metal make the crown look opaque, but you will have that awful dark line at the gumline. And if the dentist is successful in hiding that under the gum for now, in a few years the gums will often recede a little and the dark line will become visible.

So what you have is a dentist who doesn’t really care that much about how your smile looks. If you do, then you have a basic disconnect with this office. Now I want to be careful here, because many of these dentists who aren’t very concerned about the appearance of their work are excellent dentists. They are very engineering oriented and careful and thorough. They’re just not artistic. And this is the case with about 98% of dentists, maybe more – they simply aren’t artistically inclined at all.

So then what do you do about the four crowns you have? And my guess is that the dark line isn’t the only appearance-related problem with this work. They will have to be kind of opaque. I doubt they sparkle like natural teeth. And the shapes may not be natural. But replacing them with work from a truly artistic dentist will cost you another $1000 per tooth, and your insurance won’t cover that probably for another five years at least. But that is the only remedy. So when you’re ready to have them replaced, find an expert cosmetic dentist from our list and have this done right.

About the fee you paid – $989 is a typical fee for a crown. (Click here to read about costs of porcelain crowns.) The sad thing is that for that fee, or maybe just a little more, you could have had a beautiful all-ceramic crown that would have enhanced your smile rather than detracting from it. And about the metal on the back – remember that this is a porcelain fused to metal crown. They will often have a metal back. The metal back is actually gentler on the opposing teeth that chew against these teeth than the porcelain would be, and it shouldn’t be visible from the front. If you just have a spot of metal showing, then you probably had a thin layer of porcelain there over the metal. That shouldn’t cause any problem.

– 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.

March 1, 2013

Is she allergic to the metal in her crowns?

Dr. Hall,
I am 64 years old…had metal fused porcelain crowns (5 upper front teeth) placed 4 years ago. After countless dentist visits, a nightguard, a guard for my bottom teeth, tensing of the jaw, etc., I cannot stop grinding my teeth. I am constantly aware of these crowns with the sensations I feel in the roof of my mouth. Do you think that maybe I cannot tolerate the metal? Previous to these crowns, I had gold backed crowns for 42 years which I never had a grinding problem. I have no peace and I am ruining my bottom teeth. Could I be allergic to the metal? (only because it actually feels “itchy” at the roof of my mouth.)

– Mae in Pennsylvania

Mae,

I need a disclaimer because of not being able to examine you myself, but just going from what you are telling me, it sounds to me like you have two separate problems.

The itchy feeling around the metal backings to your new teeth could well be from a metal allergy. Here’s what I would do: Ask your dental office for information on the composition of the alloy used in the metal of your porcelain fused to metal crowns. The laboratory would have sent them what is called a “Identalloy” certificate, which lists all the metals in the alloy. If you see “Ni” among the metals listed – this stands for nickel, and nickel allergies are fairly common.

Are you sensitive to any metals in earrings, for example? Women who have nickel allergies need to wear hypoallergenic earrings, and they have to be careful with what metals are put in their mouth.

Let me explain these dental metal allergies. In the medical history that the dentist took before starting any treatment, he or she should have asked if you have any history of metal sensitivities, and if you have anything like that in your history, the dentist should have prescribed metals for use in your mouth that have no nickel in them. The problem is, those metals are more expensive than ones that do have nickel. There are three expense classifications of metals used in crown and bridge work. The highest is called “high noble.” The gold backing you used to have would be in this category. Other alloys have high platinum. This type of metal makes a finer margin and is more malleable, meaning that it can be made to fit the tooth the best. The second highest is called “noble.” These will have a higher silver content, but will have no nickel or beryllium, which are metals that can cause sensitivities in some patients. They are somewhat malleable and make a very nice fit to the tooth, but not as high quality as the high noble.

The lowest category is called “base metal.” These are very stiff alloys and tend to be cast with small gaps between the metal and the tooth, so they don’t fit quite as well and they aren’t malleable at all. They will have some nickel in them and sometimes some beryllium.

Your new crowns may have also disrupted your bite. The metal sensitivity shouldn’t be causing you to grind your teeth, But if you had crowns on five front teeth, that has a strong impact on your bite and your bite could be thrown off to where it is making you want to grind your teeth. If this is happening to you, I would wear a nightguard every night until the bite is adjusted to where you don’t grind any more.

A particular problem if you have porcelain crowns on your front teeth that don’t have a full metal backing is that the porcelain on the upper teeth is highly abrasive to your lower teeth, and you will gradually wear down your lower front teeth. So I would get this fixed.

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.

September 18, 2010

Allergic to the Metal in her Crowns

This is a follow-up e-mail from Carolyn in New Jersey. She asked about the types of metals that are used in porcelain-fused-to-metal crowns.

Dr. Hall,
Thank you very much for your informative answer.

At this point, my last concern is aesthetics. I seem to be reacting to a metal in my porcelain-fused-to-metal crowns. (Tongue inflammation where the tongue touches the metal parts of my crowns, inflammation in the skin on the lips and around the mouth, and general facial inflammation).

I saw the metal shell underneath each of these porcelain crowns just before they were placed in my mouth. I hadn’t been informed, first, that such a metal shell could or would exist under the porcelain, so there was no time to halt the procedure in order to seriously question the makeup of that shell. It was rough, grainy, and very dull silver-colored. I suppose this is the “black” that is now appearing near the gums. I’m guessing this would have to be a “base” metal. It certainly wasn’t “shiny.” More like the lowest grade of industrial steel.

In addition, I’d asked for a gold surface on top of some of the the porcelain crowns. I had no metal in my mouth prior to this and my goal was to have only gold, if any metal at all. I have a TMJ problem so a forgiving metal was needed on some surfaces.

Understanding completely that there is no “pure gold” for the mouth and that all gold comes as an alloy, I still cannot believe that these surfaces on top of the porcelain crowns are actually gold. They are quite dark silver now, “hot” to my tongue, they burn my tongue, and now the tongue is swollen in those places. I do have an all-gold crown, in the back of my mouth, to compare these dark silver metal surfaces to. The all-gold crown looks, feels, and acts like gold. It’s beautiful and feels good. These “gold” surfaces on top of the porcelain-fused-to-metal crowns, however, look and feel so dark and so hot. I’m suspecting an electrogalvanic reaction between the upper metallic surfaces and the baser metals at the gumline.

I’d questioned the gold content of these upper surfaces (because they looked silver) and received the answer that the colors can be different due to the fact that the gold comes as an alloy. But “this degree of different” is really strange. If my white gold ring began to look this way, I’d take it back to the jeweler for a refund.

So I’m trying to gather intelligent background information, independently, on what I might have received in my mouth that is causing my mouth and tongue to burn, and my facial/lip skin to become so inflamed with scaly red patches around the mouth. I realize that no one but my dentist can give me the chemical composition for sure. I just wanted to have a ballpark idea of what might be happening to me before I approached him on this.

In general terms in the profession: Is it possible for a patient who has paid in full for such crowns to go back, a mere two or three years later, and receive from the lab the exact metallic composition of each crown that they produced for me?

Any further information on any of these points would be greatly appreciated. I understand completely that only my dentist can give me the “bottom line” on my own case. I’m just looking for accurate ballpark info so that I do not permit myself to be led astray.

Does the black at the gumline, therefore, give evidence of a “base metal” having been used for the metal shell under the porcelain crown?

Thank you.
Carolyn

Carolyn,
No, the black line at the gumline doesn’t give any clue as to what metal you have in the crowns, nor does the rough appearance of the metal on the inside of the crown (it is left rough to be more retentive – a shiny surface would slip off the tooth more easily). But your sensitivity gives a strong clue. I would give at least 95% odds, based on your reactions, that nickel was used in your crown, as that is the metal that usually provokes this kind of reaction. That is one of the base metals.

And to answer your previous question, yes, the dentist should retain documentation of what alloy was used and its composition. The dental laboratory is required to send to the dentist what is called an identalloy certificate that lists the composition of the alloy that was used, and the dentist is required to retain this. The dentist bears responsibility for insuring that you don’t have this kind of reaction. Do you have any history of metal allergies, such as a reaction to any metals in earrings? We always asked whether people had any reaction to metals, and flagged the charts of those patients who had metal sensitivities, so I would know when to avoid base metals. Although we got to where we simply didn’t use them on anybody because of the risks involved, except for Medicaid patients, where the government specified that they wanted us to use base metals, because they were cheaper. If your dentist didn’t ask you this, then he or she is responsible for this and should make it right with you.
Dr. Hall

Dr. Hall,
Again, thanks so much. I very much appreciate your insight and your time.

The one overwhelming thing known about me by the dentist and his staff is my multiple chemical sensitivity. That reality looms larger than my name, at this point. I have been my dentist’s “chemical education,” with all the difficulties and humorous moments that implies.

Although mercury made me miserable (all those teeth fell apart and the mercury was incidentally removed before these metal-shelled crowns were installed) I never had a nickel allergy to report! I supposed now I will.

Carolyn

Links: Click here to ask Dr. Hall a question.

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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 30, 2010

What metals are in porcelain fused to metal crowns?

Filed under: Porcelain Fused to Metal Crowns — Tags: , — mesasmiles @ 11:47 pm

Dr. Hall,
I have 6 porcelain-fused-to-metal crowns. I have two questions:

1) What are the usual metals contained in the metal shell?

2) Is the metal shell the thing that begins to show at the gumline, causing the black lines? (I have those black lines.)

Thank you for your information.
– Carolyn from New Jersey

Carolyn,
There are two basic types of metals that are used in porcelain-fused-to-metal crowns – precious or noble metals and base metals. Noble metals used are gold, platinum, and palladium. Base metals would be chromium and nickel. Dentists will classify these crowns as porcelain fused to high noble, porcelain fused to noble, or porcelain fused to base metal.

The noble metals have less tendency to corrode, provoke less sensitivity, and are made to a more accurate fit.

The metal can show at the gumline, and this is what causes the dark, sometimes it’s even black, line at the gumline. Dentists may try to hide this under the gum, but after several years, sometimes the gum recedes and this line is visible anyway. The dentist may ask the dental lab to cut back the metal at this front part of the gumline and leave this margin all in porcelain. This is called a porcelain butt margin. The dentist will pay an extra fee for this – about $30 to $40, and they generally pass this on to the patient. While this makes this line more subdued, it will usually still be present. The reason is that there is still a lot of opaquer that has to be used in the crown to mask the metal. The contrast between the opaque crown and the natural tooth structure makes it difficult to blend colors here, and creates the effect of the dark line.

Patients generally prefer the all-porcelain crowns, which will eliminate any dark line. And the general natural translucency of the crown without any metal is much more natural-looking. But be careful. I would never ask a dentist who is more comfortable doing a porcelain-fused-to metal crown to do an all-porcelain crown. Dentists who are good at all-porcelain crowns will far prefer them for front teeth. If your dentist suggests a porcelain fused to metal crown for a front tooth and you are concerned about the esthetics so that you want all-porcelain, take that as a signal that you are in the wrong practice. This dentist places a low priority on esthetics and if you try to nudge them out of their comfort zone, the results could be disastrous.
Dr. Hall

Follow-up – in a subsequent e-mail exchange, it came out that Carolyn is probably allergic to the metal in her porcelain fused to metal crowns. Read the posting on dental metal allergy.

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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