按2: 结合使用小苏打和含氟牙膏。 用小苏打溶液漱口。

I'm interested in that, but I only have a few mins. Can you give me at most the first 500 characters of a detailed explanation in English about that?
Hydrogen peroxide may whiten teeth, but you need to use it with caution. To try this method, mix 2 parts of baking soda with 1 part of 1% to 3% hydrogen peroxide to form a paste. Brush your teeth with the mixture for 1 to 2 minutes, then rinse with water.  Make sure you use hydrogen peroxide with a concentration of 3% or less. Brush with hydrogen peroxide and baking soda once a week at most. Stop brushing and rinse your mouth with cool water if you feel a burning sensation. Don’t use this method