Dear Sir/Madam,
All teeth in my lower jaw are covered with crowns, but after approximately two years four crowns are already damaged: two have partially chipped and two have cracked. The crowns are all-ceramic and the teeth are subjected to normal loads. I would like to know your opinion whether this is normal. How long should all-ceramic crowns usually last? What is the usual warranty period?
Which crowns last longer: metal-ceramic or all-ceramic?
Thank you very much for your answers.

Dear Sir/Madam!

Unfortunately, I cannot give you an exact answer to any of the questions, only my opinion. In our practice we are required to give warranties on prosthetic work (7 years for fixed prosthetic restorations if they are connected). If the conditions for such warranties are impossible (we explain the problem to the patient, but the patient nevertheless insists on the treatment), we of course agree on shorter warranty periods. Therefore, the durability of crowns does not always depend only on their fabrication, but also on the conditions in the mouth, the way they are maintained, the presence or absence of the remaining dentition, ...
Metal-ceramic technology is certainly more extensively proven, but theoretically the durability of all-ceramic restorations should not be lower than that of metal-ceramic technology.

Have a nice day!