1) baking soda
2) hydrogen peroxide雙氧水(You can replace hydrogen peroxide with salt. Salt is even more abrasive so reduce the frequency.)
(3) normal toothpaste
Mix a teaspoon of baking soda with a few drops of hydrogen peroxide, brush your teeth with the mixture (should be a paste form substance). Rinse with water. Then brush your teeth with toothpaste as normal.
