Metal present in dental ceramics


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Hi Dr. Hall,
I like your website–it is informative.
I am a naturopath and need a crown. I’m concerned over some of the materials used. After my research, so I far like the look of the ceramic crowns (is this glass?) and wondering what Vita ceramic is made out of. I’m finding it hard to get an answer. I basically don’t want any with metals or lithium as I have thyroid issues.
Thank you,
Vanessa from New Zealand

Vanessa,
Any crown that is all ceramic is not going to have any metal in it. But I’m reading between the lines of your question, and I think you are asking about avoiding any metal ions in the crown. I don’t believe this is going to be possible to do, as there are metal ions in every dental ceramic I am aware of.

Let’s get into a little chemistry. Iron is a metal. Rust is iron combined with oxygen–iron oxide. While rust isn’t a metal, it has metal ions in it. And while you wouldn’t want to eat metallic iron, of course, iron ions are essential to life. They’re an important ingredient of our diet, since the hemoglobin in our blood has iron ions in it. The iron in our blood is what gives blood its red color.

Similarly, sodium is a metal. As a pure metal, it is toxic, but combined as a metal ion with chlorine it is sodium chloride, or common table salt, and is also essential to life.

Other metal ions that are important ingredients in our diet include calcium, potassium, magnesium, zinc, copper, manganese, molybdenum, and cobalt.

Lithium is a metal that is in the same family as sodium. It is so reactive that it doesn’t occur freely in nature, so it is found naturally in its ionic form combined with other elements. Lithium disilicate is a ceramic that is very strong and has been developed in the past few years to be used in dental crowns. I have in my mouth an e.max crown, which is made of lithium disilicate.

Zirconium is another metal. Combined in its ionic form with oxygen, it is known as zirconia, and is a ceramic that is even stronger than lithium disilicate and has also been developed recently to be used in dental crowns. It is so strong that it can be used in bridges without requiring a metal framework, something that is very risky with other ceramics.

You mention Vita. Vita is a brand of porcelain. Porcelain is a conventional ceramic that has been used for many years for dental crowns. It isn’t very strong by itself, but when it is bonded to tooth structure, it is strong enough for crowns on front teeth and premolars. Dental porcelains are made with kaolin as a key ingredient. Kaolin is a clay that has silica and aluminum oxide. Aluminum again is a metal, but it isn’t aluminum metal that is in these crowns but aluminum ions.

Glass is pure silica (silicon dioxide). Silicon is not a metal, but glass isn’t strong enough to be used as a crown, though there are some crowns that use a layer of glass on the outside (Empress crowns). However, the glass they use in Empress crowns is a leucite glass that has aluminum tectosilicate in it.

So you can take all of this information and figure out what you want to do. I am not aware of any biocompatibility issues with any of these ceramics. However, if you were to ask me my opinion about which one would be least likely to provoke any biological reaction, I would say the zirconia.

– Dr. Hall

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About David A. Hall

Dr. David A. 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 advanced internet marketing for dentists.

This dentist does a really fast crown preparation


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Hi Dr. Hall,
Should I consider leaving my current dentist? When I first met my dentist, I was amazed a how incredibly fast he could trim down a tooth for a crown. It seemed like less than ten seconds. However it now seems as though he shaved some teeth down too far. Two of his crowns have fallen out twice, and there does not seem to be much tooth left to hold them. Could it be that he was working too fast and took too much off of the existing teeth?
I am not planning on suing but I cannot afford to lose any more teeth to his crown work, and cannot afford implants at the moment. Should I seek out a different dentist? Is there any guarantee with a crown?
– Marcos from New Jersey

Marcos,
While there is not really a guarantee with a crown, there is a concept in dental care called the standard of care–a minimum standard that an average dentist should provide his or her patients. There may be situations where there simply isn’t much tooth left to hold the crown on, so even a dentist who is doing everything right could have problems with an occasional crown staying on. But if there are recurring problems with crowns from a particular dentist with crowns falling off, that could indicate a breach of the standard of care and the dentist could be liable.

I realize that you don’t want to sue, and I’m not suggesting that. But knowing the dentist’s liability can be used to give you a bargaining position to get things fixed correctly without having to pay another dentist to do this over.

You say that two crowns have fallen off twice, and that you could see there wasn’t much tooth left on these teeth. While I don’t know the history of these teeth, that, together with your description of how little time this dentist spent on the crown preparations, suggests to me that the teeth were prepared with too much taper. I refer you to my earlier post on this subject, The Main Reason Your Crown Probably Fell Off, where I explain the role of taper.

In over 20 years of dental practice and placing many hundreds of crowns, I never had a crown that I placed fall off. I say that not to brag but to make the point that if a tooth is properly prepared and a crown properly cemented, it will stay on. Yes, it takes more time and trouble to prepare a tooth precisely so the crown stays on, and it is also more time and trouble to seat and cement a crown with an ideal preparation, which is why most dentists compromise on the ideal preparation a little bit. It sounds like your dentist compromises a lot in the interests of speed.

So to get to the point. Yes, if I were you, I’d find a dentist who does crowns that stay on. And then I would get these two teeth fixed with crowns that stay on. It may be necessary to have new crowns made. Even if a tooth is over-prepared, there are ways to modify the preparation, either with retentive grooves, or with a buildup and possibly the use of pins, so that a crown will stay on better. Or, depending on the material in the crown, it may be possible with bonding technology to get a poorly prepared crown to stay on. I would find a dentist who can take care of this for you, and ask that dentist to help you get some type of refund, even if it’s a partial refund, from your current dentist.

– Dr. Hall

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

About David A. Hall

Dr. David A. 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 advanced internet marketing for dentists.

Why does my crown keep falling off?


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Dr. Hall,
I have had a crown put on by a dentist and it was done same day. No temporary. Not sure what type of material he used for the crown. It fell out three times in less than a year. I went to a different dentist on the fourth time it fell out and he replaced the setting with a new one stating the other dentist didn’t create a good setting. This new crown is Zirconia Porcelain and it has fallen out twice in a month. He is suggesting a full porcelain crown on the same setting as he states the cement is adhering to my tooth but not the crown. He says the all porcelain has a more rough underside to adhere to the cement better. Any suggestions on what my next move should be?
– Stephanie from North Carolina

Stephanie,
Your same-day crown was a CEREC crown or a similar type that is milled by a computer in the dental office while you wait. But when properly prepared and bonded on, it will stay on permanently. It’s not the material your crown is made of. Gold crowns, porcelain crowns, CEREC crowns, zirconia crowns–all of them can be made to stay on solidly, permanently. I have most of those types of crowns in my own mouth and they stay on just fine.

There are two main factors for retention of a dental crown–the bonding strength of the cement, and the shape of the tooth preparation. Of those two, the shape of the tooth preparation is far more important. If the tooth is prepared with only a slight taper, a crown can be cemented with a very weak cement and it will still stay on. If it is prepared with a lot of taper, some of the strongest cements will not hold it on.

I’m not saying that getting a good bond between the crown and your tooth wouldn’t solve your problem. The strength of the cement is a factor. And I know very little about your tooth and the techniques these dentists used. But I do know that a tooth prepared with good retention form will not have a crown falling off three times in less than a year, regardless of the cement used. So even though I know very little about your tooth, I’m pretty confident that it was prepared with inadequate retention form.

So what should your next move be? I would find a dentist who knows how to do crowns that stay on. In 23 years of dental practice, I never had a crown fall off of any that I did for my patients, so I know it can be done.

For further understanding of this principle, of creating a crown that stays on, see my blog post from about nine months ago, “The main reason your crown probably fell off.”

I hope this is helpful.
Dr. Hall

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About David A. Hall

Dr. David A. 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 advanced internet marketing for dentists.

Do I really need this crown on a root canal tooth?

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Hi, Dr. Hall,

I had a root canal done on a molar almost 5 years ago. After the dentist did the canal he put in a filling which has recently come out. I went back and he has told me I need a crown put in with posts, I was wondering if this is necessary rather than just getting another filling? What are the pros and cons of crowns? and is it strange that he didn’t originally put in a crown as there’s not much of the tooth left and I think he probably would’ve known the filling wouldn’t last. Any help would be great as I really don’t know what to do.
Thanks,
Melissa from Ireland

Melissa,
The only puzzling part of your situation is why the dentist didn’t recommend a crown when the root canal was first done. Now you’re in Ireland where much of the dental care is publicly funded. I’m wondering if that has something to do with this.

Not every tooth that has a root canal treatment needs a crown. I’ve written before on this blog about the need to be careful in doing crowns on front teeth that have root canal treatments, as a crown will weaken a tooth against lateral stresses. But practically every molar with a root canal treatment does need a crown. The reason is that once a tooth has a root canal treatment it tends to become more brittle over time and more susceptible to breaking. Molar teeth in particular are the most susceptible of breaking in this circumstance for two reasons. They are the teeth furthest back in the mouth, so they receive the greatest chewing pressure. Furthermore, because of their cusps, the stresses on them tend to separate the cusps, which subjects them to a high risk of cracking in two. A crown will protect the tooth against cracking in two.

So yes, I would do the crown.

And a post or posts would be needed if there isn’t much of the tooth left to hold the crown on—if the tooth is mostly filling. Otherwise you wouldn’t need a post.

– Dr. Hall

Do you have a comment? 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 A. 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 advanced internet marketing for dentists.

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