# Fabrication and Characterization of ZnO Nanoparticle‐Coated NiTi Orthodontic Wires With Enhanced Friction‐Reducing Surfaces

## TL;DR

This paper shows that coating orthodontic wires with ZnO nanoparticles can reduce friction and kill bacteria, potentially improving orthodontic treatments.

## Contribution

A novel polymer composite coating method for ZnO nanoparticles on NiTi wires is introduced, offering both high antibacterial activity and reduced friction.

## Key findings

- Polymer composite coating provided the highest reduction in frictional forces at 0° wire/bracket angle.
- Polymer-coated samples showed 89% reduction in cell viability against Streptococcus mutans.
- CVD-coated samples had 98% antibacterial activity but insufficient friction reduction.

## Abstract

The study is aimed at modifying the surface of nickel–titanium (NiTi) wire with novel coating techniques of zinc oxide (ZnO) nanoparticles (NPs) for reduction in friction and improving antibacterial activity.

NiTi orthodontic wires were coated with ZnO NPs by the chemical vapor deposition (CVD) and polymer composite coating. Physicochemical properties of ZnO NPs were assessed by field emission scanning electron microscopy (FE‐SEM), energy‐dispersive x‐ray (EDX), and x‐ray diffraction (XRD) analysis. Besides, the surface characterization of NiTi substrates was analyzed with atomic force microscopy (AFM). The antibacterial activity of the coated samples against Streptococcus mutans was assessed using the colony count method.

Polymer coating method demonstrated the most durable and well‐adhered ZnO coating among the groups with a relatively high antibacterial activity (reduction in cell viability [R
%] = 89%). The polymer composite coating group showed the highest reduction in frictional forces in 0° wire/bracket angle. The highest R
% (98%) belonged to the CVD group, but unfortunately, the reduction in friction was not satisfying.

All the coated wires represented antibacterial activity. Among the groups, the polymer coating sample obtained the highest reduction in friction and could be an attractive choice for the clinician for safer and faster orthodontic treatment.