Hydroxyapatite (Tooth enamel mineral phase) (HAP)

The tooth enamel mineral phase is the most highly mineralized tissue in the human body, composed of approximately 96% inorganic material, primarily in the form of carbonated hydroxyapatite crystals [NIH/NIDCR, 2023]. Its primary biological function is to provide a hard, wear-resistant surface for mastication while protecting the underlying dentin and pulp from chemical, thermal, and mechanical insults [StatPearls, 2023]. This mineral phase is dynamic, undergoing constant cycles of demineralization and remineralization depending on the pH of the oral environment and the concentration of ions in saliva [Aoba, 2004]. Therapeutic interventions often target this phase by introducing fluoride ions, which integrate into the crystal lattice to form fluorapatite, a more stable and acid-resistant mineral [Buzalaf et al., 2011]. Failure to maintain the integrity of this mineral phase results in dental caries, the most prevalent chronic disease globally, as well as dental erosion from extrinsic or intrinsic acids [Selwitz et al., 2007]. Modern dental materials also aim to mimic this phase through biomimetic hydroxyapatite to repair early-stage lesions.

Other names

Carbonated hydroxyapatiteEnamel mineralCalcium hydroxyapatiteBioapatiteEnamel apatite

Promotes remineralization by facilitating the deposition of calcium and phosphate ions into the enamel matrix and substituting hydroxyl groups with fluoride to form acid-resistant fluorapatite [Aoba, 2004; StatPearls, 2023].