Can multiple lab changes to porcelain crowns cause the porcelain to weaken and chip?

I have been wearing my full porcelain crowns on my front six teeth temporarily to make sure they look how I want before the dentist puts them in permanently. They have been returned to the lab numerous times to have changes made. While wearing them I noticed that one of them has chipped on the edge. Can the trips to the lab cause the porcelain to become weak? Also, is it normal for a dentist to have his assistant talk to me more than him talking to me personally about my expectations?

Doctor Answers 3

Porcelain Veneers

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Normally porcelain veneers are sturdy once bonded but fragile before cementation.  Expert labs and expert cosmetic dentists know how much it can be altered before it is redone.  As a standard procedure in my office I would not send back work more than once for revision. Other wise I will have them redo the work.

Hope this helps.


Dr. Maddahi

Porcelain Crowns

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Numerous changes to porcelain crowns can indeed weaken the porcelain, but often times when an edge chips, that can be due to an incorrect biting relationship from your upper crowns to the lower teeth. Even crowns that haven't been returned to the lab can chip when the bite isn't properly worked out.

Changes to porcelain crowns

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Yes, it is possible for porcelain to become weaker and more brittle after multiple firings. Additionally temporary cement doesn't adhere to crowns the same way that permanent cement does so it isn't as stable. I suggest trying to get your expectations met with as few visits as possible or the crowns may need to be remade. It is also possible that your dentist has an extremely well trained assistant whose job is to work with cosmetic patients. She may be better at communicating than the dentist is, or the dentist could just be getting frustrated with the situation. Either way try to be specific about your concerns but also realistic in your expectations. 

Vicki Borowski, DDS
Dallas Dentist

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These answers are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.