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

Calcium phosphate (CaP) minerals were synthesized with photo-active erbium oxide (Er2O3), and acid-resistant phase mixture of aluminum phosphate (AlPO4) and calcium fluoride (CaF2) at room temperature via precipitation from the aqueous solution of hydrated calcium nitrate Ca(NO3)(2)center dot 4H(2)O and ammonium hydrogen phosphate (NH4)(2)HPO4. The dominant precipitated phases, characterized by X-ray powder diffraction, confirmed the presence of monetite (CaHPO4) and brushite (CaHPO(4 center dot)2H(2)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 mu m 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.