Tribological and biological assessments of TaAgB solid solution coatings for orthodontic treatment

The most used metal-based orthodontic materials have poor tribological performance and no antibacterial ability in oral cavity. Their long service affects the orthodontic effect and the patients’ dental and periodontal health. Depositing functional protective coatings on metal-based material surfaces is an effective solution. In this study, a TaAgB solid solution coating was successfully prepared by magnetron sputtering technology with Ag-doping. Compared with a pure TaB2 coating and a TaB2/Ag nanocomposite coating with Ag precipitation, the solution strengthening effect gives the TaAgB coating a higher mechanical hardness of up to 34.3 ± 0.58 GPa. The tribological behaviors of TaAgB in a saliva environment revealed that the oxide lubrication phase induced by friction on TaAgB surface and the unique water-based lubrication feature of saliva contribute to the friction reduction; the corresponding friction coefficient is as low as 0.08. The characteristics of high hardness and smooth surface make the TaAgB coating show further excellent wear resistance in the low-wear process, wear rate is only 6.51 × 10−15 m3/Nm. Additionally, subsequent biological experiments confirmed that the TaAgB coating is nontoxic with good biocompatibility and antibacterial ability. The dual optimization of tribological and antibacterial properties was achieved by depositing a TaAgB coating with a solid solution structure on metal-based material surfaces. In the longer view, the TaAgB coating as a protective coating for orthodontic materials has excellent potential for application.