[downer68]

Okay, but what about stannous flouride and sodium fluoride?

No one ever discusses the toothpaste fluorine ions, in conjuction with the much more terrifying acid, which is the boogey man that haunts the fears behind fluoridated water, and so on...

[toss1]

This is a good little interesting video on fluorine here (previously linked by someone else), and the ending is the best description of tin fluoride for teeth I've ever seen -- well worth the ~6min

https://www.youtube.com/watch?v=vtWp45Eewtw&feature=youtu.be

(edit: added link)