In
fluoroapatite (P[6.sub.3]/m space group), the F ions are located along the c-axis on the mirror planes passing through the [Ca.sub.II] triangles, whereas in hexagonal HA, the O[H.sup.-] ions, with internuclear axes coincident with the c-axis, are displaced about 0.03 nm from the planes of the [Ca.sub.II] triangles with protons pointing away from the [Ca.sub.II] triangles [33]; thus, the mirror planes passing through the [Ca.sub.II] triangles are lost and the P[6.sub.3] space group results.
Hydroxy-apatite is the mineral portion of human and animal bone but is also grown naturally (along with
fluoroapatite) in thermal springs and can be grown synthetically for use in environmental remediation.
Fluoride not only inhibits the demineralization of enamel, but it can also reverse it or remineralize it by producing a new crystalline surface of
fluoroapatite nature which has a much lower solubility in the acids [21, 25].
While shark teeth contain the mineral
fluoroapatite (fluorinated calcium phosphate), the teeth of humans and other mammals contain hydroxyapatite, which is an inorganic constituent also found in bone, explained co-author Matthias Epple.
Fluorine (F) plays a critical role in the formation of
fluoroapatite.
Fluoroapatite is a mineral that is part of the enamel on our teeth.
