Hi, what a coincidence it is this thread beginning tonight. I just today went to a biological dentist for the first time after a lifetime of seeing a conventional dentist. The biological dentist strongly urged I use a toothpaste called RiseWell which contains hydroxyapatite (but not with nano particles). She said you do not rinse it after brushing, just leave it in your mouth and it will remineralize your teeth. It is available from their website, www.risewell.com and Nordstroms, oddly enough. I haven't tried it yet but wanted to share the name with you. Good luck with your tooth and missing filling!