How to Whiten Your Teeth, 1607
That Unicornu fossile is definitely legit.
Michael Bernhard Valentini, Museum museorum (1714)
The horne of an Vnicorne being beaten and boyled in wine, hath a wonderful effect in making the teeth white or cleare, the mouth being well clensed therewith.
Edward Topsell, The Historie of Foure-Footed Beastes
Wine and unicorns really do make everything better, don’t they?