How to Manage Broken Zircon Crowns?

It comes down to "you get what you pay for". There is no way to repair zirconium, so replacement is the only option. If they are all one piece, then they must all be taken off. In the process, the underlying tooth gets changed, so the extra crowns you have won't fit.

This is a complete "do over" situation.

ZIrconia crowns are used a lot now because they have tremendous strength. But almost every material can be broken or chipped when placed under the wrong conditions.

Typically if it's four front incisor teeth, they are made as single separate crowns. Occasionally and rarely, sometimes there are reasons to join some of them together. I am suspicious that your situation would not be one of those times.

It could be a lot of work and I am not even sure it would be cost effective, but a skilled dentist and lab team might be able to separate the four crowns and use one or replace the whole set as necessary.

I will aslo say this, I have only done something like this on two occasions in over twenty years of practice. I typically will not place another dentist's or lab's work. WHen I have done it I do charge for all of the time that it takes to accomplish this, which in your situation may be substantial.

Find the best cosmetic dentist you can now and see what else he can offer you for options.

I'm not sure why they made Zirconium Crowns for front teeth. They are usually NOT as esthetic. Sounds like you should start all over with a qualified Cosmetic Dentist in your home town.