Dr. Hall, you have kindly answered a dental question for me before. Currently, I am wrestling with what would be the healthiest option for a crown for me to have placed on a lower molar (next to last) which has a 30-plus-year-old crown on it and which required dental surgery to remove severe infection so the tooth could be saved. It seems my dentist saved the tooth but he wants me to return in five weeks to remove the old crown and place a new one. He mentioned zirconia but I understand this material is extremely difficult to remove should I have further problems plus I have read there is radioactivity in this material. I considered e.max and then Encore PFM which has 4o% palladium. I am confused over what would be most healthy in the long run and my dental appointment is looming. Dental issues are definitely life changing. Any clarity you can provide me would be so appreciated. Thank you.
– Sandra from Mississippi
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So which is the safest crown? It probably has less to do with the three materials you mentioned and more to do with the expertise with which the crown is crafted. Your greatest danger with a crown, among those three excellent materials, will be with recurrent decay, which will be minimized by having a precisely fitting crown. And if your dentist was able to save this tooth from a severe infection, that’s a good sign that he may have the skills to make an excellent, well-fitting crown.
Yes, there are trace amounts of radioactivity in zirconia. Some zirconia materials used in dentistry are refined to minimize that radioactivity. But even without that, the amount is extremely small. There is also radioactivity of a similar amount in brick, stone, and concrete. Actually, there is even some radioactivity in water.
Some people also question whether or not there is an allergic sensitivity of some people to zirconia. We had one report of that and then it turned out to be a case of burning mouth syndrome. And yes, zirconia is very difficult to remove, but that is the dentist’s problem, not yours. He or she may wear out a diamond bur or two trying to get it off if that ever becomes necessary, but that won’t hurt your tooth any. The e.max crowns are also difficult to remove, porcelain fused to metal not so much.
If you are allergic to a lot of things, an all-ceramic crown would seem to be a good choice. The two popular, strong ceramic materials are zirconia and lithium disilicate. The CEREC crown-in-a-day is made out of lithium disilicate. The e.max crown is made of a lithium disilicate core veneered with feldspathic porcelain. It can be made highly aesthetic and has become very popular with dentists because of its strength, aesthetics, and the ease of working with it. I have one of those on a first premolar. But if you want the safest, longest-lasting crown on a lower first molar, cast gold would be the material of choice. Whether or not that would show would depend on how wide your smile is. I have crowns on three of my second molars, and they are all cast gold. Gold can be cast to a very fine margin, won’t ever break under the most severe oral stresses, and is extremely biocompatible. After gold, the strongest material for a crown for a molar would be 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.