baking soda on a toothbrush, but make sure you brush your teeth afterwards with regular toothpaste. and don't overdo it, it'll start to break down your enamel after a few weeks

I agree with Leesha I've tried it so many times and it did work....do this only twice a week to make sure you don't cause any damage to your teeth....some say strawberries when brushed into your teeth do the same effect....I will definitely try it!

There are certain toothpastes that are supposed to whiten teeth. I think they have baking soda in them kinda like the two girls said. You might want to check with your dentist first, though, to be sure it's safe.