Hydroxyapatite
also Hydroxylapatite, HA, CaHA, Apatite CaOH
| physical | Naturally occurring mineral form of calcium apatite. Pure hydroxylapatite (HA) powder is white. Naturally occurring apatites can, however, also have brown, yellow, or green colorations. | ||
| chemical | Ca5(PO4)3(OH) | ||
| occurrence | Carbonated calcium-deficient HA is the main mineral of which dental enamel and dentin are composed. HA crystals are also found in the small calcifications, within the pineal gland and other structures, known as corpora arenacea or ‘brain sand’ | ||
| properties | HA has good biological properties. | ||
| applications | HA is commonly used as a filler to replace amputated bone or as a coating to promote bone ingrowth into prosthetic implants. Implants, e.g. hip replacements, dental implants, can be coated with HA. | ||
| biocompatibility | very good | ||
| special | n/a | ||
| adverse effects | Low bioresorption rate in vivo, poor stimulating effect on the growth of new bone tissues, low crack resistance and small fatigue durability in the physiological environment. | ||