I like Uncle Harry's (Calcium carbonate (natural chalk), sea salt, mustard seed powder, essential oils of peppermint, eucalyptus, clove, wintergreen, and oregano) for powder but the flavor is pretty strong. They do have a lighter version called Children's and a non-flavored.
My favorite is Earth Paste lemon flavor (Water, Bentonite Clay, Xylitol, Sea Salt, Essential Oil (lemon, lemon verbena, tangerine and lime). which is very mild. My husband likes Squigl Tooth Builder (
https://www.squigle.com/tbingredients.html) which tastes mildly sweet.