Methods: Mineralization solutions were prepared to yield final concentration of 2.5 mM Ca+2, 1.5 mM phosphate, and 2 mg/ml LRAP (GL Biochem China) (pH=7.2). 1 ppm F- was added to the selected solutions to study the effect of fluorine ion. Calcium phosphate or fluorine-containing (1 ppm) solutions were used as the controls. The solutions were incubated at 37°C for 72 h. Transmission electron microscopy (TEM), atomic force microscopy (AFM), and selected electron area diffraction (SAED) techniques were used to study the mineralization characteristics.
Results: SAED analysis revealed diffraction patterns corresponding to the apatite structure in all solutions. TEM analysis showed that in LRAP-containing solutions fibers of hydroxyapatite or fluoroapatite arranged in bundles, while in solutions without LRAP, the crystallization occurred without that arrangement. AFM imaging showed the hierarchical prismatic assembly of HA and FA crystals, similar to the enamel structure.
Conclusions: LRAP can regulate the crystallization of calcium phosphate and produce prismatic structures like dental enamel. Therefore, LRAP-CP has the potential to be used as a remineralizing agent for enamel reconstruction.