Dental enamel hydroxyapatite hydroxyl sites (HAP hydroxyl sites)

Dental enamel hydroxyapatite hydroxyl sites are the specific locations of hydroxyl (OH-) ions within the crystal lattice of hydroxyapatite [Ca10(PO4)6(OH)2], which constitutes approximately 96% of dental enamel (Dorozhkin, 2016). These sites are essential for maintaining the structural integrity and chemical stability of the tooth mineral under physiological conditions. In the presence of organic acids produced by plaque bacteria, the hydroxyl ions are prone to dissociation, leading to demineralization and the formation of dental caries (Fejerskov, 2004). Therapeutic interventions, most notably fluoride treatments, target these sites through an ion-exchange mechanism where fluoride ions replace hydroxyl ions to form fluorapatite [Ca10(PO4)6F2] (Aoba, 1997). Fluorapatite possesses a lower solubility product and greater resistance to acid challenge compared to the original hydroxyapatite, effectively armoring the enamel against further decay. Additionally, these sites participate in the dynamic remineralization process where calcium and phosphate ions from saliva are redeposited into the enamel matrix (Cury & Tenuta, 2009).

Other names

Hydroxyapatite hydroxyl groupsEnamel mineral hydroxyl positionsOH- sites in hydroxyapatite

Substitution of hydroxyl ions with fluoride ions to form acid-resistant fluorapatite and promotion of remineralization.