Dear Dr. Hall,
I have had a Maryland Bridge for more than twenty-five years. I am a horrific grinder and have to put off getting a bite plate. I had 2 crowns put in a few weeks ago and the dentist worked on getting a comfortable bite. In the process of doing this he took a bit off of the Maryland Bridge tooth. Next day I noticed a silver dot showing through the Bridge tooth. Went back to the dentist and he said it was from me grinding which I disagree with. He placed a bonded composite filing over it. The silver dot is showing through again.
After twenty-five years of having the bridge could this silver dot of the tooth appear overnight from grinding? Again, I realized this the morning after he adjusted my bite and took off some of the tooth. I don’t know how to approach this because he said it was a result of my grinding. Thank you for any help you can provide.
Maria from New Jersey
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Well, I can’t see the Maryland bridge or the spot that is now showing through, but you and I both know that if it hadn’t been for the dentist adjusting your bite this wouldn’t have happened. He might be technically correct—he just thinned the porcelain and overnight your grinding finished removing the last thin layer of porcelain over this spot. He doesn’t want to admit that his grinding had a role because that would obligate him to possibly having to replace this Maryland bridge. And because of his authority relationship with you, you feel very uncomfortable contradicting him.
Here’s what I would suggest. Find a dentist who will give you a second opinion. Many dentists will do that for no charge. Ask them to tell you if there are signs of grinding of the porcelain right around this spot where the metal is showing. If you drag a metal explorer over glazed porcelain, it won’t leave a mark. But if the porcelain has been ground on with a dental bur, the explorer leaves a distinct mark on the porcelain. So it’s pretty easy to tell when porcelain has been ground on. Then, armed with the opinion of another professional, that will give you the courage to go back to your dentist and hopefully get him to fess up. It would help if you’re not too accusatory. This is an understandable mistake by your dentist. I will bet that almost every dentist has had an experience adjusting the bite on a porcelain-fused-to-metal crown and ending up with some of the metal showing through. While I never had that happen on a front tooth, I had that happen to me several times on back teeth. Here is a photograph of three crowns on back teeth where the porcelain was adjusted down to the metal on two of them:
Is it possible to repair this without replacing the Maryland bridge? Maybe, but it’s tricky. Your dentist put composite over the spot, but it doesn’t sound like he did anything special to prepare the surface of the metal, and without that the composite will not bond at all to the metal and thus won’t last more than a few hours. There is a dental bonding cement called Panavia that will bond to metal. The way to try to repair this spot would be to grind away some more of the metal to give some room for some thickness of material. Then it would be best to etch the metal with a small sand blaster called a micro-etcher. This will make the spot larger, but you do what you have to do—you’re trying to save the bridge. The metal then needs to be primed and a thin layer of opaque Panavia would then be placed over the metal, cured, and then the correct shade of composite would be placed over that, shaped, and polished. And then you would cross your fingers and hope that this works.
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