Hydroxyapatite crystal lattice (HAp (or HA))

Hydroxyapatite crystal lattice describes the repeating atomic structure (crystalline arrangement) of hydroxyapatite, chemically formulated as Ca₁₀(PO₄)₆(OH)₂, which crystallizes in the hexagonal system (P63/m symmetry) with defined lattice parameters (a ≈ 0.9432 nm, c ≈ 0.6881 nm)[2][4]. This lattice features channels and arrangements for calcium and hydroxyl ions and is responsible for the hardness and structural properties of bone and teeth. Hydroxyapatite is not a druggable target, receptor, enzyme, or transporter in the conventional sense—rather, it is a mineral phase and therefore does not fit the definition of a molecular therapeutic target or receptor[4][6]. The hydroxyapatite crystal lattice can undergo substitutions (e.g., fluoride, carbonate) and may have imperfections such as calcium or hydroxyl vacancies, which alter its properties in vivo[4][2]. It is widely used synthetically in dental and orthopedic materials due to its close resemblance to native bone mineral[6]. While the compound hydroxyapatite is biomedically relevant, the crystal lattice itself cannot be targeted by drugs or considered a therapeutic molecular target in the receptor/enzyme/transporter sense.

Other names

Hydroxyapatite crystal structureHydroxylapatite latticeHA latticeHAp lattice