How do toothpaste manufacturers get away with saying their product whitens teeth...when in fact they don't?

Toothpaste will never whiten your teeth.
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The FDA doesn't control "whitening" since it's cosmetic. They will generally say "will get your teeth their natural whitest" Which means, the toothpaste is abrasive and will remove stains. Some "bleaching" toothpastes contain peroxide which will help maintain the color you have or lighten a little.
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