hydroxyapatit

Hydroxyapatit (hydroxyapatite) is a calcium phosphate mineral with the chemical formula Ca10(PO4)6(OH)2. It is the principal inorganic component of bone and teeth, forming crystalline apatite that provides stiffness and a reservoir of calcium and phosphate ions. In biological systems, carbonate and other substitutions occur, yielding a range of compositions known as biological apatite.

Hydroxyapatit crystallizes in a hexagonal lattice. It is relatively insoluble at neutral pH but dissolves under acidic conditions. It is biocompatible and bioactive, capable of bonding to bone (osseointegration) and supporting osteoconduction, the growth of bone on its surface.

Natural hydroxyapatit is found in bone mineral and tooth enamel, dentin, and cementum. The mineral in bone is often poorly crystalline and substituted with carbonates, magnesium, and hydroxide vacancies.

Synthetic hydroxyapatit is manufactured for medical and dental use. It can be produced by precipitation from calcium and phosphate solutions, as well as by hydrothermal, sol-gel, or other methods. Applications include bone graft substitutes, coatings on orthopedic implants to improve osseointegration, and drug delivery systems. Nano- and micro-scale hydroxyapatit is used in toothpaste and remineralization therapies.

Limitations include brittleness and slower resorption compared with some other materials. To tailor properties, researchers employ dopants, composites, and ionic substitutions to adjust solubility and bioactivity. Overall, Hydroxyapatit is valued for its biocompatibility, bioactivity, and relevance to bone and dental health.