Effect of Ag-PTFE nanocomposite coating on wettability and antimicrobial activity of orthodontic wires

This study investigates the effect of Ag–PTFE nanocomposite coatings, prepared by radio frequency (RF) sputtering, on the surface and antimicrobial properties of orthodontic stainless steel archwires (SSW). The novelty lies in combining silver (Ag) and polytetrafluoroethylene (PTFE) nanoparticles into one coating, which has not been widely applied to orthodontics. The motivation is the need to reduce microbial adhesion and biofilm on archwires, which contribute to enamel demineralization, gingival disease, and infections. The problem addressed is the lack of coatings that can simultaneously provide enhanced surface properties, facilitate controlled silver ion release, and deliver durable antibacterial performance. Unlike literature that mainly studied Ag or polymer coatings separately, this work fills the gap by varying Ag and PTFE weight percentages and assessing their combined effects on wettability, roughness, ion release, and antimicrobial activity. Austenitic 316L stainless steel archwires (0.4 mm in diameter and 160 mm in length) were coated using Ag and PTFE nanopowders (30 nm). The coated SSW was characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and contact angle measurements, while silver ion release was analyzed by atomic absorption spectroscopy. Antimicrobial efficacy was tested against Streptococcus mutans and Staphylococcus aureus. The results showed uniform coatings with distinct hydrophobic behavior and antibacterial activity. Increasing Ag content enhanced silver ion release and inhibition zones, while higher PTFE content increased hydrophobicity, reducing bacterial adhesion. These findings highlight Ag–PTFE coatings as a synergistic strategy to improve surface properties and suppress microbial colonization, suggesting potential benefits in preventing caries and periodontal complications.