Evaluation of the Effects of Two Different Nano-Bioceramics on Improving the Properties of Dental Amalgam

Amalgam is one of the most commonly used dental restorative materials, whose clinical use is still a matter of controversy among researchers. The alloy is criticized due to its mercury content and its dangers and limited resistance to corrosion in the body. In the present study amalgam/nano-hydroxyapatite and amalgam/nano-bioglass composites were produced to eliminate the currently existing limitations and evaluate the effect of the type of reinforcing agent on the mechanical properties and corrosion resistance of amalgam. In this analytical in vitro study, amalgam/nano-hydroxyapatite and amalgam/nano-bioglass composites with 2 wt% of nano-bioceramic were produced. Nano-bioceramic was added to the amalgam powder before adding mercury, followed by mixing with mercury in an amalgamator and compression in a steel mold. The microstructure of hardened samples was evaluated by scanning electron microscopy (SEM). In addition, the mechanical properties of the composites were evaluated using a universal compression test device. Resistance to corrosion of composites was studied by potentiodynamic polarization method. To compare the quantitative data, one-way ANOVA was performed using Graph Pad Prism 6 software (α = 0.05). The results showed that by increasing both bioceramics of hydroxyapatite and bioglass, corrosion resistance of composites increased, with hydroxyapatite exerting a greater impact on corrosion resistance of amalgam in the saline solution. In addition, incorporation of 2 wt% of bioglass and hydroxyapatite resulted in 12 and 15 percentages of improvement in the mechanical properties of the composites. The developed amalgam basic composites seemed to be good choices for restoration of posterior teeth, with less harmful effects (lower corrosion and higher strength), and hydroxyapatite nanoparticles were more effective than bioglass.