Here is what I found on the web.
Like coffee and colas, tea can stain teeth, although it’s not as big an offender as tobacco (smoked or chewed). Any food or drink capable of staining clothes or carpets can also stain teeth – that includes fruit juices, red wine, blueberries, soy sauce, and curry. Good quality green tea that is really green in color is less likely to stain teeth than inferior grades of “green” tea that looks brown when brewed. The best way to get rid of stains from any food or drink is with professional teeth cleaning, but afterward, it’s up to you to keep your teeth free of stains from foods and beverages.
I just got my teeth whitened at the dentist and it cost me a pretty penny. Now I feel like I must try to protect my investment. I’m thinking I’m just going to have to mainline caffeine into my system.
And here is another link: