have stained crowns and fillings...need to whiten teeth!
Teeth whiteners only work on natural tooth structure, so the shade of crowns and filling material will not change. Your teeth will whiten, but the rest will not. It is important to consider this before proceeding with the whitening process. If you already have fillings on your front teeth, it's possible to redo the fillings with a lighter shade of filling material, and you could also redo a crown in a lighter shade if that's what you needed to do to have lighter teeth match the work you have done.
It is not possible to whiten a crown or composite filling with whitening treatment. The enamel of teeth will lighten but the shade of the restorations will not change. Sometimes plaque or calculus on the teeth can be cleaned and help to make restorations look better but overall the original shade will be as white as it could possibly be without planning replacement.