Durability evaluation of different coating methods of ZnO nanoparticles on NiTi orthodontic wires and their friction with stainless steel brackets

Abstract

Aim: To modify the surface of nickel-titanium (NiTi) wire with various coating methods of zinc oxide (ZnO) nanoparticles (NPs) in different shapes and sizes for reducing friction and enhancing antibacterial activity. Materials & methods: NiTi orthodontic wires were coated with ZnO NPs by the Chemical Vapor Deposition, polymer composite coating, chemical depositon, sol-gel and electrospinning methods. Chemical, physical and morphological properties of ZnO NPs were assessed by Field emission scanning electron microscopy (FESEM), energy dispersive x-ray (EDX), and x-ray diffraction (XRD) analysis. Surface characterization of NiTi substrates analyzed with atomic force microscopy (AFM). Results: Polymer coating demonstrated the most durable and well-adhered ZnO coating among the groups with a relatively high antibacterial activity (Reduction in cell viability=89%). The chemical group showed decrease in frictional forces in 0º angle between wire and bracket. The highest R% (98%) belonged to CVD group but unfortunately the reduction in friction was not satisfying. Conclusion: All the coated wires represent antibacterial activity. Among the groups, polymer coating obtained the highest reduction in friction and could be an attractive choice for the clinician for safer and faster orthodontic treatment.