Here's some info on teeth and tea:

German researchers have found that green tea can be good for your teeth. The scientists have found that the tannic acid in green tea can be beneficial for blocking some bacteria. Black tea can also have the same therapeutic result since it contains the same acid. But, while you're sipping your tea, you may want to have a chunk of cheese as well. Researchers say cheese can
leave a protective film over teeth.
a.. Hanover - Cheese and green and black tea are good for the teeth, German experts say.
b.. The fat in cheese lays a protective film over the teeth while the calcium it contains promotes remineralisation, according to the Hanover-based health insurers Techniker Krankenkasse.
c.. Good news, too, for tea drinkers: the tannic acid contained in green and black tea helps check certain bacteria.