Enamelon Toothpaste from the 1990s:

"proven to strengthen tooth enamel" I remember researching the stock and deciding not to buy.

It seems the company is still around https://www.enamelon.com

What about "Sensodyne Pronamel"? There is usually someone in the comments raving about its effects.

I think usually they rave about Novamin, which, at least in Canada, isn’t in the Pronamel line IIRC but in other Sensodyne branded toothpastes.

_EDIT: “repair and protect”_

	▲	opello 5 hours ago \| parent [-]
		This was a good comment thread on which brands or markets had what with regard to hydroxyapatite: https://news.ycombinator.com/item?id=36564190

omlet 13 hours ago | parent | prev [-]

Did you tried :D ?