Mechanical properties and biocompatibility of various cobalt chromium dental alloys

Abstract

Cobalt-based metal alloys are often used in dentistry for prosthetic restorations because of their considerable wear and corrosion resistance. For this reason, the effect on the human body of three Co–Cr based alloys, named "Co–Cr", "C" and "L", differing in their concentrations, for subsequent use as dental materials, has been studied and compared. Metallographic observations of the microstructure, electrochemical and three-point bending tests were performed. The metallographic investigations showed similar dendritic microstructure of the Co–Cr and L dental alloys, as well similar porosities and defects. From the corrosion and pitting potential tests, it was found that the samples show surface passivation, reaching closed corrosion potential values from 0.280 V vs SCE to 0.250 V vs SCE. The Pitting Resistance Equivalent Number (PREN) values are above 38 for all the samples, which means that the studied alloys have a high resistance to pitting corrosion. Likewise, when applying the Electrochemical Impedance Spectroscopy technique, a slightly higher corrosion resistance was observed for sample L, since corrosion resistance tends to increase as the applied potential is more positive and as the impedance and phase angle values are higher. Moreover, in the three-point bending test, the alloy C presents the lowest values of the elastic modulus of 134 ± 13 GPa. The analyzed Co–Cr alloys are recommended for the efficient treatment of patients with dental prostheses that have metal frameworks, as shown by all of the obtained results.