That all depends which type of teeth whitener you choose; an abrasive whitener will try to remove a thin layer of stained enamel. These should only be used if your enamel is of good condition I.e. not thinned down.
However, there are also whiteness that will stain your teeth white thus inhibiting the use of an abrasive product but the whitening effect will not last very wrong and will have to be re-applied.
Hope this helps