Biomimetic hydroxyapatite as a multifunctional agent in preventive dentistry

Objectives: Due to its similarity to the natural enamel crystallites, particulate hydroxyapatite, Ca₅(PO₄)₃(OH), is used in biomimetic dental care, and as a material for tooth restoration. We investigated the adhesion properties of hydroxyapatite to the tooth surface and conducted an in-depth literature research to elucidate its effects and the related modes of action in preventive dentistry.
Methods: We conducted a comprehensive literature research on the efficacy of hydroxyapatite in different fields of preventive dentistry using the scientific databases PubMed and SciFinder. We included published in vivo, in situ, and in vitro studies focusing on caries, periodontitis, dentin hypersensitivity, erosion, and whitening. Additionally, we analyzed the adhesion properties of a pure hydroxyapatite powder to enamel and dentin surfaces in an in-depth in vitro study using high-resolution scanning electron microscopy (SEM).

Results: Our SEM study indicates that the adhesion of hydroxyapatite particles to enamel and dentin surfaces is promoted by the formation of mineral-mineral-bridges. Published studies confirm the efficacy of hydroxyapatite-based dental care formulations in the prevention of caries, periodontitis, and dentin hypersensitivity in vivo as well as in the reduction of bacterial colonization to enamel surfaces in situ. A recently published clinical multicenter study confirms the non-inferiority of a hydroxyapatite toothpaste to a fluoridated control toothpaste in the realm of caries prevention in high caries-risk subjects.

Conclusions: In contrast to fluorides, which are preferably used in caries prevention at present, the biomimetic agent hydroxyapatite offers additional advantages in modern dental care across all age groups. In addition to caries prevention and control, other beneficial properties of hydroxyapatite particles reported in the literature include relieve of dentin hypersensitivity, reduction of bacterial colonization to enamel surfaces, and gentle whitening effects on tooth surfaces.