Influence of Physical Dimension and Morphological-Dependent Antibacterial Characteristics of ZnO Nanoparticles Coated on Orthodontic NiTi Wires.

White spot lesions (WSLs) are one of the adverse effects of fixed orthodontic treatments. They are the primary sign of caries, which means inhibiting this process by antibacterial agents will reverse the procedure. The current study tested the surface modification of nickel-titanium (NiTi) wires with ZnO nanoparticles (NPs), as antimicrobial agents. As the morphology of NPs is one of the most critical factors for their properties, the antibacterial properties of different morphologies of ZnO nanostructures coated on the NiTi wire were investigated. For the preparation of ZnO nanostructures, five coating methods, including chemical vapor deposition (CVD), chemical precipitation method, polymer composite coating, sol-gel synthesis, and electrospinning process, were used. The antibacterial activity of NPs was assessed against Streptococcus mutans by the colony counting method. The obtained results showed that all the samples had antibacterial effects. The antibacterial properties of ZnO NPs were significantly improved when the specific surface area of particles increased, by the ZnO nanocrystals prepared via the CVD coating method.

Zinc-oxide nanocoating for improvement of the antibacterial and frictional behavior of nickel-titanium alloy.

AIM: To fabricate a friction-reducing and antibacterial coating with zinc oxide (ZnO) nanoparticles on nickel-titanium (NiTi) wire. MATERIALS & METHODS: NiTi orthodontic wires were coated with ZnO nanoparticles using the chemical deposition method. Characteristics of the coating as well as the physical, mechanical and antibacterial properties of the wires were investigated. RESULTS: A stable and well-adhered ZnO coating on the NiTi wires was obtained. The hardness and elastic modulus of the ZnO nanocoating were 2.3 ± 0.2 and 61.0 ± 3.6 GPa, respectively. The coated wires presented up to 21% reduction in the frictional forces and antibacterial activity against Streptococcus mutans. ZnO nanocoating significantly improved the surface quality of NiTi wires. The modulus of elasticity, unloading forces and austenite finish temperature were not significantly different after coating. CONCLUSION: This unique coating could be implemented into practice for safer and faster treatment to the benefit of both patient and clinician.