Most of my teeth have crowns will teeth whitening work on them?
Unfortunately it is not possible to change the colour of porcelain crowns. Porcelain crowns are made either by layering porcelain and baking these layers at high temperatures in a furnace, by pressing a porcelain “ingot” into the required tooth shape or by milling a porcelain blank to the desired shape. All these processors produce a very stable end result without the possibility of changing the colour.
There is a possibility of having the front of your crowns resurfaced with porcelain veneers but this is likely to produce a less than satisfactory result due to the likelihood of the underlying metal or opaque substructure showing through. The only sure way for you to have a brighter smile is to have your crowns replaced.
Glad to hear you are getting your jaw problem sorted out and sorry that there is not an easier solution to your whitening problem.