Is It Possible For A Veneer To Be Used Over A Molar That Has Had A Crown On It Before?

Q.
Hi. I have had some very nice porcelain and metal crowns for the last 20 years on three molars that had a lack of enamel when they erupted. Two of these crowns are on opposing molars, and the upper one has had to be replaced due to a small cavity. I was told a crown of the same type wouldn’t be a problem but the new crown arrived looking like a marshmallow with huge metal patches showing through the chewing surface of it. I have had two different dentists tell me that this can’t be helped and any and all replacements would come back the same way because there isn’t enough space to accommodate a porcelain and metal crown like my original, and the only option for me is a plain metal crown. The space is less than 1/16th of an inch, and my dentist wants to avoid reshaping the tooth as it was already very short. She also doesn’t want to risk damage to the root and tooth because aside from the small cavity, it is in good condition. In such a case of a lack of space, is it possible for a veneer to be used over a molar that has had a crown on it before? If so, would it affect or be affected by a porcelain and metal crown below it?
A.
If the space is that thin then covering the metal with porcelain could be a problem and the ideal thickness of purely porcelain (be it a ‘veneer’ or crown) is 1.5-2mm on the biting surfaces. If the tooth has already been crowned then a veneer (on a back biting tooth this is known as an ‘onlay’) is not suitable as more tooth is generally removed for the crown in the first place. Maybe get a second opinion. There are porcelains that are very strong such as E-max ‘Monolithic’ which might be possible but we’d usually have our ceramic technician look at the space available to see if it’s enough or if more tooth preparation is required. Regards, Mark.
dr mark hughes

Dr Mark Hughes

Harley Street Dental Studio
52 Harley Street, London W1G 9PY
Web: www.harleystreetdentalstudio.com Tel: 020 7636 5981

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