Everybody wants a whiter and brighter smile. If finance is an issue, it's a good idea to try some over-the-counter whitening products, for example crest strips. As far as the three crowns that you want to replace, it might be a good idea to do the crowns one at a time. Start with the one that is more visible and the one that bothers you the most. After a few months you can replace the other two crowns.
It is possible that your old retainer would not fit because you had some work done on your front teeth.
Depending on how much tooth is left at how strong it is, might be savable by performing rooot canal therapy therapy, post and a crown. However; if the tooth is not savable, the three unit bridge can restore your missing tooth. An implant is also another option to restore your missing tooth. See your dentist as soon as possible because there could be an infection which can cause more serious problems.
Tooth fracture is common on teeth with root canals. It is difficult to answer your questions without seeing the X-ray. However, an 8 mm pocket is very serious. An exploratory surgery can be done to see the extent of the fracture. If the tooth has completely separated in two pieces, an implant is the best choice.
There are few options to consider to correct your issues and the cost of the treatment should not be the only factor. The most conservative approach is #1 Invisalign. It is possible to shift your teeth and close the spaces without shaving your teeth. You do need retainers after your treatment is complete. Option #2 is composite bondings, although it costs less, often times they chip, break off and stain over the years and need to be replaced. #3 Veneers, cost more, very aesthetic and natural looking, need to be replaced in a few years. Don't think how much it will cost now. Think in the long term which option is best for you.
