I have a fake tooth that is more discolored than the others, can xylitol whiten even that tooth?
It depends why the fake tooth is discolored.
If this was an old plastic tooth - then the color probably will not change. If the tooth has surface stains - and it used to be a different color- then the cleaning may help remove some of these stains.
I would suggest using the system, even if the fake tooth looks out of place for a few months. Then you could talk with a dentist about a new fake tooth - to match the color of your nice clean, shiny, healthy real teeth!
Thanks for the question and wishing you a Happy New Year! Ellie