You can run, but you can’t hide. The same can be said about disturbingly yellow teeth. Your teeth are covered with a smooth enamel that is naturally white. The enamel wears out over time but certain habits, dietary and otherwise can accelerate it.
Put a tiny bit of toothpaste into a small cup, mix in one teaspoon baking soda plus one teaspoon of hydrogen peroxide, and half a teaspoon water. Thoroughly mix then brush your teeth for two minutes. Remember to do it once a week until you have reached the results you want. Once your teeth are good and white, limit yourself to using the whitening treatment once every month or two.