Please explain in detail what exactly is a Diagnostic Wax Up?

Diagnostic waxups aren't required to do great dentistry, but they are immensely helpful. I usually tell patients that a diagnostic waxup is like a blueprint for how we want your final restorations to be fabricated. You wouldn't consider building a house without a blueprint, nor do I remove tooth structure without knowing exactly where and how much to remove. The waxup also allows the dentist to make temporaries that are very close in contour and shape to the anticipated final restoration. If you want changes made the temporaries can be altered and that information translated to your lab. This way there is no guess work or disappointment at the final appointment.

A diagnostic wax-up is where models of your teeth are re-shaped with white wax, usually by a lab to precisely shape and design your crowns so you and the dentist can see what the result will be and it meets all requirements before the teeth are prepped. The wax-up can be used to fabricate provisional crowns and even be a template for the final crowns. This is the technique I always use when doing several crowns or a complete make-over. Good luck.

I'm sorry you are unhappy after 3 re-makes from the original crowns.  However without photos of before and after and study models I can not analysis the problem you are unhappy about.  If you are really serious about doing it again...seek a new opinion that will include before and after xrays, existing and new study models & of course, a wax-up of what the next new crowns should look like.  Good luck.

A diagnostic waxup involves making the changes you and your dentist thnik need to be made on models of your existing teeth.This is done when you are anticipating a big difference from what you have initially, for example, closing gaps, lengthening teeth, changing tooth position. It gives you a visual to look at and say this is want I want or not. It can help to determine the final result because it can be used for the temporary crowns. Wearing these would give you time to see how they feel and look and to work out anything that needs to be worked out, oftentimes the bite. If the temporaries are what you and your dentist want, then an impression of them and the diagnostic waxup can be sent to the lab to help them see what changes they need to incorporate.  If you were not looking to make anything but minor changes from your existing teeth, then a diagnostic waxup was not needed. You didn't say what wasn't right...if the color was off or the teeth too bulky,etc. Four times back to the ceramist seems excessive to not resolve the problem.

There is no guarantee that doing a diagnostic wax up will prevent any problems when doing esthetic work.  A diagnostic wax up is an estimate, using wax, of what you want the teeth to look like and function like once the work is completed.  It is done before the work is started.  But it is not done in every case and again, you can run into problems even with a diagnostic wax up.  It sounds like your dentist is doing their best to create a result that you will like.  Sending a case back 4 times is a lot and is very frustrating for everyone involved.  If you are still not happy with the results I would suggest asking your friends if the things that bother you are something they even notice.  You can also have a conversation with your dentist to see what your options are.  If you are still not satisfied a second opinion may also be helpful.  Good luck!