Structure of Hydroxyapatite Crystals

Hydroxyapatite (HAp) makes up about 70 percent of the weight of our bones and 96 percent of the weight of our teeth. Hydroxyapatite crystals organized in bundles called prisms, are the major component of dental enamel. These crystals are known to deteriorate with age.

Crystal Development

• Hydroxyapatite crystals are formed in the developing enamel matrix by enamel proteins organized into spherical substructures. The enamel crystals are formed separately from the adjacent dentin crystals.

Crystal Structure

• Hydroxyapatite crystals are made up of dahlite, which contains mostly calcium and phosphate ions, intermixed with fluor ions. These crystals form extremely long parallel bundles in dental enamel.

Crystal Deterioration

• Research done at Cornell University shows that the crystallinity of the dental hydroxyapatite decreases with the tooth's age. The study involved samples from individuals ranging in age from 17- to 87-years-old. The study found that, up to about age 45, the teeth showed highly crystallized material and the patterns from older-age teeth had an increasing increasing loss of crystallinity as they aged.