It's not necessarily the abrasive action that whitens teeth. Baking soda just sitting on the teeth can do that.
"Baking soda gives your teeth a whiter appearance by removing tough stains. Baking soda works to actively remove dulling plaque and deep stains that are embedded deep in tooth surface crevices by dissolving into these areas. Once dissolved in water, baking soda changes its chemical make up slightly and it gives off free radicals which penetrate the surface of the tooth’s enamel and combine with stain molecules breaking carbon double bonds; changing stain molecules from a darker coloured substance to a clear one allowing baking soda to help lighten and “whiten” teeth. If your teeth have more yellow and brown stains these are easier to change than gray stains. So the answer I have come up with is YES. Technically baking soda does help to “whiten” teeth."
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Point is, be gentle... it does work, wonderfully.
