Hydroxyapatite

2022-04-03: reference:

Hydroxyapatite $\ce{Ca5(PO4)3OH}$ #

Notice the prevalence of Phosphate though. The $\ce{OH^-}$ can be replaced by Fluoride, Chloride, or Carbonate. When it incorporates fluoride, it forms calcium fluoroapatite, which has crystals larger, shinier, smoother, stronger, and is more shapely than typical enamels in the Teeth.