regarding baking soda being abrasive i had always heard that too. but, i then came across info that compared the abrasiveness of baking soda and leading toothpastes and the baking soda was much less abrasive than the leading toothpastes. here's a link.
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Interesting. Baking soda feels more abrasive than regular toothpaste to me. Maybe the concentration makes a difference. Thanks for the link.