Jeremy B. Jorgenson, DDS

I would agree with the dentist you saw. Anytime you have a gap in-between teeth it acts as a food trap. This trap can cause decay, infection, bone loss and possible eventual tooth loss. Unfortunately you just had the crown placed two years ago but that doesn't change the need for a new crown today. If the new crown is made properly you will eliminate that food trap and any of the possible negative outcomes associated with the food trap. Good luck! 

It is very likely that a new cap/crown will affect the fit of the retainers. I would let your dentist know beforehand, however, you may still need new retainers after the cap is placed. Good luck!

You could try bonding first. This is the cheaper, quicker way to close the gap. However, you may not be happy with the esthetics of bonding. It will make your front two teeth appear very large. Veneers are more aggressive and costly but you would get a slightly better esthetic result. I would suggest braces or invisalign again to close the gap and then wearing a retainer so the teeth do not move back again. Good luck!

This would really depend on why the crown and post came out. Usually, it is due to poor condition of the tooth. In these instances the tooth has to be removed most of the time. If there was a cement failure and the tooth was fine than it may be possible to just re-cement. You would really need an evaluation and X-ray to determine the condition of the tooth. Good luck!

If you don't like the size,shape,shade of your existing metal crowns than that can all be fixed with new all ceramic crowns. Let your dentist know exactly what you don't like about your teeth and they should be able to improve those things with new crowns. The all ceramic crowns are much more aesthetic and natural looking than the older metal crown types.