ELECTROCHEMICAL CORROSION OF DENTAL ALLOYS

In the state-of-the-art dentistry, the metal materials are widely used, and their number is constantly increases. The disadvantages of such materials include their electrochemical and corrosive activities in the oral cavity. A number of factors, such as chemical composition, microstructure, fabrication method, and surface treatment, can cause the electrochemical degradation of dental alloys. This review deals with alloys used in contemporary dental orthopaedics, concerns the effect of alloying impurities and protective coatings as well as modifying the structure and chemical state of the surface on its corrosion properties. Properly chosen alloying of metals allows not only increasing some of the corrosion-mechanical characteristics, but also, as a result, to prevent the occurrence of pathological manifestations in the oral cavity. Different types of high-energy surface treatments lead to specific changes in the physicochemical structure of the thinnest surface layer. A special attention concerns the methods of severe plastic deformation and laser treatment of the dental alloy surfaces. As shown, the improvement of the corrosion properties of dental metal alloys as a result of ultrasonic impact treatment occurs due to the nanostructuring of the surface and the formation of a surface layer with high-passivating properties. Laser irradiation also increases the corrosion resistance of dental alloys in the corrosive medium and results to a significant decrease in the value of the corrosion potential, thereby minimizing the negative effect of the metals of the alloy on the human organism. However, we have to note that the works aimed to improve the physicochemical properties of the dental-alloys' surface via both the laser treatment and the ultrasonic impact processing are currently at the initial stage of their development and has not yet received practical application in the dentistry.