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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.
Vanessa from New Zealand
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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