Red Wine
Red wine is one of the most common sources of discoloration in people’s teeth. The exact scientific reason for this isn’t known, but many different substances produce the effect in red and white wines and other substances like coffee and tea. One cause is a chemical called tannin, which is found in all wines.
Tannins give the wine its astringent taste (the feeling of dryness when you drink it) and the tan color of tea bags. They’re also what stains your teeth when you drink wine or coffee. Tannins are very hard to remove from teeth, especially if they’ve been there for more than a few hours—overall, they’re not something that should be ingested frequently or in large amounts.
When tannins come into contact with your mouth’s moisture, they react with the proteins that make up your saliva to create colored compounds called anthocyanins. These pigments are most strongly present on your front teeth, so if you touch your lips to your front teeth (as opposed to those at the top or bottom), you’ll see that they’re the ones that have the most color.
