I'd assume fluoride. On a recent trip to the dentist, I was told I'd had the start of a cavity that had re-crystalized (I believe that was the term). The Americ

I'd assume fluoride. On a recent trip to the dentist, I was told I'd had the start of a cavity that had re-crystalized (I believe that was the term). The American Dental Association [0] and an arm of the NIH [1] appear to back this up, as well: > Fluoride is a mineral that can prevent tooth decay from progressing. It can even reverse, or stop, early tooth decay. [0] https://www.mouthhealthy.org/en/fluoride-superhero https://www.mouthhealthy.org/en/fluoride-superhero [1] https://www.nidcr.nih.gov/health-info/tooth-decay/more-info/tooth-decay-process https://www.nidcr.nih.gov/health-info/tooth-decay/more-info/...