Comparative evaluation of the effect of clinical procedures on the corrosion of four brand dental amalgams

Amalgam restorations often tarnish and corrode in the oral environment. The degree of tarnish and the resulting discoloration appear to be dependent on the parameters such as oral environment, oral hygiene, and the particular alloy employed and clinical procedures. The aim of this research was to evaluate and compare the effect of clinical procedures such as carving, carving-burnishing and carving-burnishing-polishing on the tarnish and corrosion behavior of four brand dental amalgams. Method & Materials: Four different type of commercial amalgam alloy powders with different powders with various particles shape (lathe cut, spherical, spheroids) namely Sybraloy (Sy), Cinalux (CL), Oralloy (Or) and cinaalloy (Ca) were studied. A special mold was used to prepare the samples of each type of commercial amalgams. Twenty-one samples of each type of amalgams were prepared. After trituration and condensation, the samples of each type of amalgams were divided into three groups and each group was finished by using one of three procedures carving, carving-burnishing, carving-burnishing-polishing. Electrochemical potentiodynamic tests were performed at a temperature of 37±1 °C in order to determine and compare the corrosion behavior of dental amalgams, as an indication of biocompatibility. The results showed statistically significant differences between the mean corrosion current densities values of three different groups of each type of commercial amalgam (P<0.05). The polished group of each type of commercial amalgams possesses the lowest corrosion current density and the carved group shows the highest corrosion current density (the lowest corrosion resistance). This trend was not affected by the brand and chemical composition of commercial amalgams. The polished Sybraloy amalgam possesses the highest corrosion resistance between four types of polished amalgams and the polished Cinaaloy amalgam showed the lowest corrosion resistance. The similar trend was observed in carved group and carved-burnished group of four types of amalgams. It was concluded that the clinical operations and procedures could influence the tarnish and corrosion behavior of high copper dental amalgams. Polishing procedure increases the corrosion resistance of high copper dental amalgams and is more effective on the corrosion behavior of dental amalgams, which are less corrosion resistant in compare with the dental amalgams that are more corrosion resistant.