In the state of Washington only the dentist can legally permanently cement a crown. This is to assure that it is done correctly and so the dentist cannot lay the blame on one of his employees. Anything can be redone if necessary.
In many cases this can be restored with a composite restoration in one appointment. The larger or deeper to the tissue the fracture went will affect the long term success of the restoration. I have done these numerous times when a patient can't afford a crown or isn't mentally prepared to get their first crown.
You didn't say if your daughter had a root canal done on the tooth or not. If not, she most likely will in the future. If she has, then you can do an internal or non-vital bleach that many times can return a tooth to it's normal color. This is done by placing a very strong bleaching material into the chamber of the tooth that has had root canal therapy. It can't be used with a normal live tooth.
I am on the other side of the fence even though I don't perform orthodontics myself. I don't know if it is a case of you not wearing your retainer long enough or do to what appears to be a low frenum attachment above you front teeth. The frenum is the web of tissue beteen your upper lip and the tissue adjacent to you teeeth. If that attaches to close to the teeth, then the muscle fibers can force the teeth apart over time. A fairly simple surgery can easily correct this problem. I myself had orthodontics a second time in my fifties and I plan to wear my retainers as long as I am physically and mentally capable. You are young and have very nice looking teeth andI I would hate to see you have them unecessarily and irreversibly prepped by having tooth structure removed for bonding. You have to remember that bonding permanently alters your teeth and like any restoration will not last forever and most likely will have to be redone over the years depending on your age when you first have them done.
A new properly designed and fitted bridge should not be coming uncemented twice in a year unless it had been temporarily cemented in order to see how you liked it or how the teeth supporting it are doing. The bottom line is the dentist came up with this treatmant plan and it does not seem to be working. Sometimes the dentist just has to admit it is not going wwell and has to do whatever it takes to make the patient happy. I have had to redo a bridge, but it was for esthetic reasons which is always a judgement call, and not for the design or fit. When treatment goes as wrong as you are describing, most dentist would go to whatever lengths necessary to avoid things going outside of your office and getting real ugly.
