Calcium Phosphate

September 14, 2017

Calcium phosphate is a family of materials and minerals containing calcium ions (Ca2+) together with inorganic phosphate anions. Some so-called calcium phosphates contain oxide and hydroxide as well.

It is used in some varieties for bone substitution as implant.

Orthophosphates, di- and monohydrogen phosphates contain Ca2+ combined with PO43−, HPO42−, and/or H2PO4−:

  • Monocalcium phosphate, Ca(H2PO4)2 and Ca(H2PO4)2(H2O).
  • Dicalcium phosphate (dibasic calcium phosphate), CaHPO4 (mineral: monetite) and a dihydrate CaHPO4(H2O)2 (mineral: brushite).
  • Tricalcium phosphate (tribasic calcium phosphate or tricalcic phosphate, sometimes referred to as calcium phosphate or calcium orthophosphate, whitlockite), Ca3(PO4)2
  • Octacalcium phosphate, Ca8H2(PO4)6.5H2O
  • Amorphous calcium phosphate, a glassy precipitate of variable composition that may be present in biological systems.

Di- and polyphosphates contain Ca2+ combined with the polyphosphates, such as P2O74− and triphosphate [P3O10]5−:

  • Dicalcium diphosphate: Ca2P2O7
  • Calcium triphosphate: Ca5(P3O10)2

Hydroxy- and oxo-phosphates contain other anions in addition to phosphate:

  • Hydroxyapatite Ca5(PO4)3(OH)
  • Apatite Ca10(PO4)6(OH, F, Cl, Br)2
  • Tetracalcium phosphate (CAS#1306-01-0): Ca4(PO4)2O

Calcium sulfate has been used for bone substitutes for long time. Peltier et al. (1957) mixed a plaster of paris (POP), calcium sulfate hemihydrates, and water allowing to set in the mold to make column- and tablet-form calcium sulfate dihydrate. The set plaster was used to fill defects in dog bone.