Toothpaste, mouthwash, gum, even dental floss all have something in common: the default flavor is mint. We don’t even say “lozenges” when we talk about the everyday remedy for bad beneath -we call them “breath mints.” Is there something about mint that is better at masking bad breath than other flavors? Not really.
What's more, says cosmetics historian Rachel Weingarten, "the idea that mint equals freshness is more of an illusion than anything else. It's a triumph of advertising."
Peppermint does include menthol, which triggers receptors in your mouth that make it feel cold. But exclusively linking this feeling to our concept of "fresh breath" is pretty arbitrary — other countries, after all, have very differently-flavored toothpastes, such as clove and aloe.
Honestly, mint was always useful, as a flavoring or medicine, but the idea that it cures bad breath better than other strong flavors is was pretty recent, and mostly made up by people who wanted to sell us something. Read how marketers convinced us that we all need mint to fix our bad breath in an article at Vox. -via the Presurfer