In Vitro Remineralization of Acid-etched Bovine Enamel with Amino Acids/Hydroxyapatite Composite

Remineralization of early enamel caries lesions plays a crucial role in prevention and restoration of dental caries. Based on the crucial amino acids contained in enamel matrix, amino acids /hydroxyapatite (AA/HAP) composite was synthesized in the presence of 10 mmol/L glycine, 10 mmol/L L-serine and 5 mmol/L L-aspartic acid. The physical, chemical and biological properties of the composite were characterized. And its remineralization effect on acid-etched bovine enamel was evaluated. Under the inhibition properties of amino acids, the composite has lower crystallinity and higher biocompatibility compared to the hydroxyapatite (HAP) without amino acids. In vitro remineralization of acid-etched bovine enamel using AA/HAP was conducted in artificial saliva. After remineralization, the surface and cross-section morphology, the components, and the mechanical property of bovine enamel samples were characterized, respectively. The results showed that the AA/HAP could induce the restoration of both surface and subsurface enamel lesions. The amino acids released from the composite could adsorb on the organic matrix residues and induce the formation of parallel arranged HAP crystals, eventually formed significant surface microhardness (SMH) recovering.