10. Bottled Water
While bottled water may taste better than tap in some places, your teeth will miss the added minerals like fluoride that come standard when you pour yourself a tall one from the faucet. Alternatively, fluoride supplements can free you up to enjoy your bottle of Fiji.
Smoking cigarettes, in addition to all of the other health hazards it presents, is one of the worst things you can do for the health and appearance of your teeth.