For those of you with incipient tooth problems, perhaps caused by "bone thinning" - please make sure you are getting enough Vitamin D3 and, above all, Vitamin K2. I cut back my D severely for some time, because I'd had a high reading and, because I thought maybe I was taking too much K2 (apparently it is safe at high doses, but still...), I halved my dose of that. And after some months my teeth, which used to be very sensitive but had been much better for a while, started to to get sensitive again. Started to take a little D3 again, and went back to earlier higher dose of K2. It can't be coincidence that within a very few weeks the teeth are no longer as sensitive, and continue to improve.