For white teeth:

You will need:

-baking soda

-water

 mix a teaspoon of baking soda and a pinch of salt with a small glass of water until mixture is paste-like. Brush teeth as usual and rinse well. It is proven that baking soda will help lighten stains, but be careful not to use too often. Once every two weeks should be enough, as baking soda can be abrasive and erode tooth enamel.