Development and Characterization of Silane Coated Miniaturize NdFeB Magnets in Dentistry

The main reason limiting long-term clinical application of neodymium-iron-boron magnets in dental field is their marked corrosion tendency in middle aggressive media containing chloride such as saliva solution. Thereby it becomes necessary to overcome the corrosion resistance lack of Nd–Fe–B magnets with new wear resistant encapsulating materials or surface coatings. With this aim, in this work a multi-layered organic–inorganic struc- ture able to supply specific functional properties to the whole assembly (i.e., anticorrosion resistance, wear resistance, biocompatibility and durability) was proposed. The influence on the magnetic force of a new hybrid coating consisting in 0, 1, 2, 3 silane layers on nickel plated magnets was tested. Furthermore the degradation of the samples was evaluated by data analysis collected by EIS (electrochemical impedance spectroscopy), during aging time in synthetic Fusayama saliva solution at pH 5.5 and morphological analysis by 3D Digital Microscope. The experimental data confirm that the presence of coupling agent does not affect the magnetic force of Nd–Fe–B magnets and that the new coating provides a barrier effect in biological environment without affecting the biocompatibility of the system. Thus the limiting aspect preventing the use of Nd–Fe–B magnets for dental applications can be avoided by using silane agents as surface coating.