Magnetron sputtering methods for surface modification of shape memory alloys for applications in orthodontics and endodontics

Various magnetron-sputtering methods for surface modification of shape memory alloys (SMA) are described in this paper. These methods belong to the most effective methods, which enable mechanical reinforcing of the SMA, showing numerous advantages over conventional methods of electro-polishing. In addition, surface modified SMA, particularly with equiatomic TiNi coatings, is crucial for further development of various endodontic instruments; wires and brackets used for orthodontic teeth movements. Active coatings with bactericide properties and coatings that can be used as barrier for release of toxic Ni ions from the bulk body of SMA obtained by various magnetron-sputtering methods can be successfully combined. Therefore, the review of these methods is given in this paper, with their main characteristics and drawbacks. Magnetron sputtering deposition involves surface modification of SMA in a single-layer, multilayer, graded layers, and nanocomposite thin coatings for obtaining systems with superior "functional" characteristics. These are hardness, scratch, abrasion, and erosion resistance, improved adhesion to various technologically important substrate materials such as polymers, hydrophobicity or hydrophilicity, long-term chemical, thermal, and environmental stability, gas and vapor impermeability, and others. This paper is critical review of the advances in the development of magnetron sputtering modified SMA products in dentistry, with in advance predictable physicochemical, structural and antimicrobial properties.