Enamel hydroxyapatite crystal structure (None in widespread scientific use (abbreviations like HAP or HA refer generally to hydroxyapatite, not specifically enamel hydroxyapatite crystal))

Enamel hydroxyapatite crystal structure describes the highly organized arrangement of carbonated hydroxyapatite crystals forming dental enamel, the hardest tissue in the human body. Enamel is composed of roughly 95–98% calcium and phosphate ions that make up hydroxyapatite crystals, with minor organic matrix (mainly enamelin protein) and water[1][5][6]. The crystals form long, thin fibers aggregated into rods (also called prisms), each 4–8 μm in diameter and oriented roughly from the dentin-enamel junction to the enamel surface[1][5]. Microscopically, individual hydroxyapatite crystals within these rods are typically 25–50 nm thick, up to 1000 nm long, and are arranged in bundles with complex but misaligned orientation of their axes, which contributes to enamel’s toughness and crack-deflecting properties[5][6]. Naturally occurring hydroxyapatite in enamel is less pure than synthetic forms, containing carbonate and trace elements such as magnesium, strontium, lead, and fluoride, which affect its solubility and physical properties[1][3][4][6]. This structure enables teeth to withstand significant mechanical and chemical stress, but is vulnerable to acid attack, resulting in dental caries through demineralization when oral pH drops below 5.5[1][5]. The enamel hydroxyapatite crystal structure is not a therapeutic target in the conventional sense, but is crucial in dental health and restorative materials science.\n\nIf you need further structured information (for example, about the proteins or biologically active sites involved in formation or biomineralization of enamel), those would be targets such as *amelogenin*, *enamelin*, etc., rather than the mineral crystal structure itself[2][3][6].

Other names

Enamel hydroxyapatiteCarbonated hydroxyapatite (in the context of enamel)Dental hydroxyapatite

None for classic drug targeting\nFluoride ions can substitute hydroxyl groups in hydroxyapatite, forming fluorapatite and making enamel more resistant to acid dissolution