here's something else that's curious - all these studies are in vitro and many of them coat the teeth in "acid resistant nail varnish" before soaking them in lactic acid (the chemical that oral bacteria produces that breaks down enamel) to produce caries.

so, in order to create fake cavities, they protect 98% of the tooth with nail varnish, then dip it in lactic acid. and, that works to protect 98% of the tooth from cavities.

it's not hard to understand why using nail polish on your teeth is a bad idea. but, are there non-toxic versions of this?