Whitening crowns? I did not know crowns could not be whitened when I had this done.

Most cosmetic dentists will have this discussion with the patient before doing any crowns in the front of the mouth. Standard protocol is if doing a few crowns or veneers, to match the adjacent teeth. If the patient wants their teeth to be whiter, then usually a patient will bleach their teeth first, then wait two weeks for the bleaching to "normalize", and then have the new crowns or veneers made to match the "normalized color".However, many patients choose to do four, six or eight porcelain veneers or crowns, and this way they can choose almost any color they want from the teeth shade guide. Huge advantage over just doing a few teeth and bleaching, as over time the bleaching will diminish and need to be repeated, while the veneers or porcelain crowns are color stable and won't get darker or discolor over time.

Unfortunately, Crowns cannot be whitened. The time to pick the desired color was BEFORE treatment started. You should have approved the color BEFORE the crowns were permanently inserted.