After about a week I inquired as to her results. Here is her reply:
Hi Bill, I've been giving it twice a day for about a week (using a small syringe) and I haven't really seen any improvement. I used Karen's stuff for a bit, then bought my own at a health food store (also 20ppm). I'll keep trying until my bottle runs out, but I'm worried he'll need teeth pulled after all...
Thanks for looking into it. I appreciate your interest :)