(CNBC) — It’s one of the most universal recommendations in all of public health: Floss daily to prevent gum disease and cavities.

Except there’s little proof that flossing works.

Still, the federal government, dental organizations and manufacturers of floss have pushed the practice for decades. Dentists provide samples to their patients; the American Dental Association insists on its website that, “Flossing is an essential part of taking care of your teeth and gums.”

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