Morphology and Fluorescence of Y₂O₃:Eu³⁺ Nanophosphors and Dispersibility in Adhesives Resins

Abstract

After orthodontic treatment has been completed, we consider fluorescent imaging to be one of the most effective solutions for secure removal of colorless residual adhesives from tooth surfaces using cutting instruments. Nanoscale Y₂O₃:Eu³⁺ particles were synthesized using the homogeneous precipitation method with two different starting concentrations of urea aqueous solutions, followed by firing at 1000°C. These particles exhibited narrow size distribution (approx. 200-300 nm) and sharp crystallinity regardless of the urea concentration. Moreover, their photoluminescence peak corresponded well with the typical 4f-4f transitions of Eu³⁺. The Y₂O₃:Eu³⁺ particles were almost uniformly dispersed and retained in the monomer blends and polymerized bulk bodies. Photoluminescence measurement is a valid detection method and can be useful for future studies on dispersion control. We conclude that the crystalline Y₂O₃:Eu³⁺ particles could be applicable for further development of fluorescent orthodontic adhesives.