Try out this! Baking Soda and Lemon Juice Paste. Mix 2 teaspoons of baking soda with enough fresh lemon juice to form paste. Wipe your teeth with a paper towel. Put the paste onto your toothbrush and apply. Leave the paste on for a minute and rinse, so as to avoid the acid effecting enamel. If you are using water instead of lemon juice, you can leave it on for up to 3 minutes. With regular use, you would see the changes. http://www.teethwhiteningkit.org/blog/best-5-home-remedies-for-yellow-teeth