Hydroxyapatite refers to one of the prime components of and an important element of usual teeth and bone. It forms the matrix of teeth and mineral of the bone. It is the hydroxyapatite molecule that gives the teeth and bones their rigidity. These molecules can combine together to produce microscopic clumps.
About seventy percent of the bone comprises of the inorganic mineral hydroxyapatite that comprises calcium carbonate, calcium phosphate, calcium hydroxide, calcium fluoride, and citrate.
The formula for hydroxyapatite is Ca5(PO4)3(OH) which means that the elements are Calcium, Phosphorus, Oxygen and Hydrogen.
Hydroxyapatite is a naturally occurring mineral form of calcium apatite with the formula Ca, but it is usually written Ca₁₂ to denote that the crystal unit cell comprises two entities. Hydroxyapatite is the hydroxyl endmember of the complex apatite group.
