Dear Dr. Hall:
I had asked my dentist to use a gold alloy crown on my root-canaled tooth #15. When I asked about the alloy that was used, my dentist hadn’t even obtained the alloy certificate from the dental lab. So he got it from the lab, and I found out that the crown was made with 35% Palladium, 30% Indium, 30% Silver, 3% Zinc and ONLY 2% Gold. While the root canal itself was done properly, I am very much worried about Palladium and especially Indium in my crown for systemic impact on my health and allergic issues (though the dentists say there is no apparent allergic reaction around the
tooth) which from certain on and off vague external and on face skin reactions. Are these materials questionable? Especially Indium which I believe does not have long history of use in the crown. I would greatly appreciate your response. Thanks.
I found you by searching for dental crown metals.
Ranjit from New Jersey
(See Dr. Hall’s answer below.)
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I don’t have any good information about the incidence of indium allergy or indium sensitivity. I haven’t heard of any. When I search online, there are some questions about it but no hard data. Indium is frequently used in alloys for dental crowns, but it’s usually present at a much smaller percentage, maybe 5% or less. Its use in such a large amount here appears to me to be a way to make the alloy a little softer without using as much gold, thus making it a cheaper alloy. There are two reasons gold is such a good metal for dental crowns. One is that it will not corrode. Another is that it is soft and thus the margins of the crown can be burnished to the tooth to make an excellent fit of the crown, eliminating the gap between the crown and the tooth that can harbor bacteria that will cause recurrent decay. Palladium is a very hard metal, so the inclusion of indium and silver will make the alloy softer, helping it fit better.
Palladium has also come under question. Are there documented palladium allergies? I can’t find any. You can read my earlier blog post where I answer the question, Is palladium a toxic metal? Palladium is present in almost all dental crown alloys without any apparent adverse reactions.
Do you need to be concerned about possible reactions to this alloy? I don’t know. If you are sensitive, yes, you would expect to see some inflammation where your gum tissue touches the crown. You’re not having that, so that’s a good sign.
But I will tell you that I am very suspicious of what your dentist did here. You asked for a gold crown, and it’s looking to me like he found an alloy as cheap as possible that could be called a gold alloy. And I do not believe that your dentist didn’t get the identalloy certificate until you asked—I think he threw it away. By law, the laboratory is supposed to send that certificate with every case and the dentist is supposed to put it in the patient’s chart. Is this an effort to conceal or just sloppiness? I don’t know, but I’m suspicious.
There are three broad categories of dental alloys that are used in crowns:
– high noble (called gold)
– noble (called semi-precious)
– low noble (called non-precious)
There are two requirements for an alloy to be called high noble or, in common terminology, gold. First it must have at least 60% of a combination of gold, platinum, palladium, and silver. Your alloy comes in at 67% there, so it meets that requirement. But the second requirement is that it needs to have at least 40% gold, so your alloy comes in way short on that.
Here is a sample of an identalloy certificate that should be sent by the laboratory every time a dental restoration is shipped to a dentist. This one is color coded yellow, meaning that it is a high noble or gold alloy. You may note that it has 2.6% palladium and 1.6% indium.
Please note the instructions at the bottom of the form: “DENTIST CERTIFICATE (attach to patient record).” I’m wondering why these instructions weren’t followed.
My advice here? If you have any reason to believe that you are having a reaction to this alloy, I would demand that your dentist replace the crown with a more suitable alloy or you will file a complaint with the dental board. In accepted terminology, your dentist did not give you a “gold” crown, which would mean using a high noble alloy. You got a semi-precious crown, which is a step below and cheaper.
– Dr. Hall
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