Characterization of Rare-Earth Oxide Photoactivated Calcium Phosphate Minerals for Resurfacing Teeth

Calcium phosphate (CaP) minerals were synthesized with photo-active erbium oxide (Er O ), and acid-resistant phase mixture of aluminum phosphate (AlPO ) and calcium fluoride (CaF ) at room temperature via precipitation from the aqueous solution of hydrated calcium nitrate Ca(NO ) ·4H O and ammonium hydrogen phosphate (NH ) HPO . The dominant precipitated phases, characterized by X-ray powder diffraction, confirmed the presence of monetite (CaHPO ) and brushite (CaHPO ·2H O) at room temperature. The microstructural analysis showed the presence of platelet-like features of monetite and brushite, which were tested for occlusion of dentinal tubules via irradiation with a 100 fs pulse duration laser, operating at 1520 nm at 2.5 GHz repetition rate. The SEM analysis of dentinal tubule over the occluded surface showed a continuum of 10 μm layer, which covered several 100s of micrometer surface. The results open the opportunity for dentinal tubule occlusion via ultrafast laser sintering using acid-resistant minerals.