See here: https://medium.com/@ravenstine/the-curious-history-of-novami...

Basically FDA won't let them label it without studies. Other countries consider toothpaste a cosmetic and don't requite studies.

You can get it on Amazon, since they don't do a ton of vetting or enforcement. You can also get toothpaste with Biomin, a substantially similar deal (its manufacturer claims it's better).

For me, novamin/biomin didn't seem to make a difference with tooth sensitivity.