LAUSR

Abstract Orthodontic brackets based on transparent ceramics in the visible area (especially magnesium aluminate, MgAl2O4) are considered for high strength, but the most important drawback of transparent magnesium aluminate is the lack of fracture toughness. In this research, the silicon nitride nanoparticles as a reinforcing phase were used to improve the fracture toughness of magnesium aluminate orthodontic brackets. For this purpose, firstly, MgAl2O4 reinforced with 2% Si3N4 nanostructured granules were prepared using the spray drying method. Then, the nanostructured granules were spark plasma sintered (SPS) at 1400 °C under pressure of 100 MPa. Finally, with the help of the diamond cutting tool, the heat-treated sample was cut into an orthodontic bracket. The results of the tetrazolium-based colorimetric assay (MTT test) showed that the produced orthodontic brackets have excellent biocompatibility with human osteoblasts cell.