Tribological behavior of the Zirconia / Ti 6 Al 4 V system used in dental implants

The aim of this work was to help to understand the tribological behavior of the pair ZrO2/Ti6Al4V, commonly used in dental implants. This is a critical aspect for the stability and durability of these devices. After characterization of the materials topography, morphology and wettability, the friction coefficient (μ) was determined in a nanotribometer in dry and lubricated conditions. Experiments were carried out in water, saliva electrolyte solution, solutions of the main biomacromolecules present in saliva (albumin, mucin and lysozyme) and also human saliva. For a ZrO2(sphere)/Ti6Al4V(flat surface) geometry it was concluded that although the μ obtained in lubricated conditions is very similar for the various lubricants, it is lower in the presence of aqueous albumin solution and even lower with saliva. Unexpectedly, the μ obtained in dry conditions was significantly lower than in lubricated conditions. It was therefore decided to investigate the behavior of the inverse geometry: Ti6Al4V(sphere)/ZrO2(flat surface). In this case, μ in dry conditions is slightly higher than in lubricated conditions, where no significant differences were observed for this parameter. Tribocorrosion experiments showed that differences inμ between the two geometries are due to differences in the passivation film. The effect of TiN coating on the Ti6Al4V flat surface was also investigated. It observed that μ decreased in all cases, being this effect more pronounced in lubricated conditions. This approach seems promising to improve the performance of dental implants.