system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How can a whitening toothpaste actually whiten our teeth if we rinse as soon as we're done brushing ?

To me it seems like all we're doing is cleaning out teeth, but there's no way they will actually whiten ...
gpt
First, those toothpastes are not really very good for your teeth. They use harsh and/or abrasive materials (baking soda or peroxide) to whiten which are, again, not super healthy. 

But, that means that the action of brushing your teeth is what actually does the whitening bit. If you brush your teeth *correctly*, that stuff should be rubbing on your teeth and staying on them for several minutes. That's time enough - it's supposed to be an application that works over time, not instantly. 

But, again, don't use those.