The Study of Ni-Cr, Co-Cr Dental Alloys and Ceramics Chemical Indifference using ZrO₂-HfO₂-Y₂O₃ System in Vitro

The purpose of this study was to find out the electrical-chemical behavior of Ni-Cr, Co-Cr alloys and ceramics using the ZrO₂-HfO₂-Y₂O₃ system in vitro. The study was conducted using the System NH (Germany) and Starbond CoS (Germany) prefabricated alloys, previous processing-free; and the Nacera Pearl (Germany) ceramics using the ZrO₂-HfO₂-Y₂O₃ system, represented with frames manufactured in a dental technical laboratory, without subsequent veneering. There were two identical samples, each of them put in the electricalchemical cell with 3% NaCl water solution, its temperature equal to 37°C. The potentials were evaluated using the potentiostat which defined the data of both samples in the cell. The experiment lasted for 5 days. The obtained results were recorded each hour throughout the working day. The parameters (values, positive or negative charge) of electrical-chemical potential on both identical samples from the System NH alloy have been changing intermittently. We have concluded that under certain conditions there may appear electrical current between the samples obtained from the same alloy, located in the same medium, unaffected by any external factors (heat, mechanical influence, etc.). The up-to-date methods of measuring the potentials and currents between the metallic dental prostheses may reflect the electrical balance by the photo, at the certain moment, so they are characterized by sufficiently high margin of error to be used while deciding on the certain alloy.