I mean you can buy it here in a normal store. So I'm not sure if you mean a dentist can't use/provide it, or if you're thinking about the nano forms of it.
Edit, just saw this:
the FDA regulates dental products like toothpaste as cosmetics rather than therapeutic agents for cavity prevention
Interestingly, many ingredients used in dental care, including fluoride, are employed off-label. This means they are used in ways not officially approved by the FDA but are still considered effective based on scientific evidence and clinical practice
I'm hoping more for brain preservation (non-upload, lower cost like chemical fixation+non-cryo). Get me out of here.