fuck.
see, this is why people don't trust dentists - they take the fluoride out of the water, then make it impossible to buy supplements. it sure seems like a giant scam, to try to force you to go to a "professional" and shell out for it.
maybe it's just capitalism, granted. but, i actually think you'd be forgiven for deducing there's something nefarious going on, and i'm not convinced there isn't, myself.