If you have noticed, the common ingredients in almost all recipes are baking soda, glycerin, and peppermint oil. Baking soda whitens teeth as well as forms the base of the recipe whereas the thickness can be altered by the use of glycerin, and peppermint oil adds flavor. Instead of using peppermint oil every time, you can also opt for spearmint oil, cinnamon oil, anise oil, wintergreen extract, and clove oil.