Ever had a problem with your teeth, it looks like it’s been colored over (maybe yellow or green). I’ve had this problem for a while and found a quick simple solution, baking soda:
Take a pinch of Baking Soda and place it on a wet cotton swab, then simply scrub off the tea stain =D. And if you don’t have time to go to the dentist and get a professional to whiten your teeth use the same technique with baking soda and you’ll get the same results.