I agree that the Calcium formula (with comfrey, unless there is a condition of concern there) would be a great thing to take internally, in any form (tea, capsules, tooth powder/packed between cheek and gums at night). It is high in easily assimilated mineral packages that include and support calcium. The Silica in the horsetail grass is the essential mineral, in my opinion. I've read that our bodies use more silica than they do calcium, and that it is essential to enamel strength and possible repair. When all these minerals are abundant in our bodies, they will be suspended in our saliva and fill weak areas from the outside, while the bloodstream feeds the tooth from below.
My experience with the formula has been great: goodbye pregnancy charley horses and hello to much healthier baby teeth in my herb-raised little children!
I loke the idea of adding cayenne as an additional circulation stimulant (the cloves and mint and any essential oils you add would do this too)... that would surely speed the healing process! I'll start doing that (ooh, don't inhale!), but I'm sure my children wouldn't go for it.
BF&C is a good formula too.