Hydroxyapatite in dental enamel (HAP or HA)

Hydroxyapatite is the main inorganic mineral component of dental enamel, making up approximately 95% by weight of enamel as highly organized, carbonated hydroxyapatite crystals formed from calcium and phosphate ions[2][4][5]. These crystals provide enamel with exceptional hardness and durability, forming a dense lattice that protects underlying tooth structures from mechanical forces and acid attack[2][3][4]. Enamel hydroxyapatite is arranged in long, thin structures known as enamel rods, surrounded by interrod enamel with different crystal orientation[2]. Demineralization (loss of calcium and phosphate from hydroxyapatite) is a key process in dental caries, while remineralization restores the crystal structure, a process promoted by calcium, phosphate, and fluoride ions[5][6]. Hydroxyapatite is not a protein receptor, enzyme, or typical drug target, but a naturally occurring bioceramic and critical substrate in dental health interventions. Drugs and biomimetic agents interact physically or chemically with hydroxyapatite to promote enamel repair, not through classic molecular targeting[1][2][5][6].

Other names

HydroxylapatiteHapHABiological hydroxyapatiteCarbonated hydroxyapatite

Remineralizing agents promote deposition of calcium and phosphate ions to repair and rebuild hydroxyapatite crystal structure. Fluoride ions can substitute for the hydroxyl group in the crystal to form fluorapatite, which is more acid resistant[5][6]