Ti-Nb-Zr system and its surface biofunctionalization for biomedical applications

In the biomedical field, a main challenge is to find a material that can provide all the requirements imposed by biomedical applications, including consisting of biocompatible elements; a low elastic modulus to avoid the stress shield effect in bone fixation; a high wear-corrosion resistance; proper biocompatibility; etc. Presently, metallic materials are the most used in biomedical applications, especially for the dental and orthopedic fields. The most common is the Ti-6Al-4V alloy. However, due to the fact that Al and V can cause mutagenic, cytotoxic, and allergic reactions, the current research has been focused on replacing the Ti-6Al-4V alloy with one consisting only of biocompatible elements. Various systems have been proposed, and in recent years, a novel Ti-Nb-Zr system with different compositions has been developed, as Zr and Nb are known to be more biocompatible than Al and V. Nevertheless, these systems still have low osseointegration and bioactivity, which limits their use for biomedical applications. Based on this, the functionalization of their surfaces by various bioactive coatings was proposed. Also the peptide coatings were proposed for improving their osseoconductivity along with good bioactivity and antibacterial properties. The present chapter reports the general classification and fabrication methods of titanium alloys and their use in medicine as well as experimental details regarding the Ti-Nb-Zr system used for biomedical applications, such as elastic modulus, corrosion resistance, and in vitro biological properties. Attention is then devoted to methods for improving the osseoconductivity and bioactivity of the Ti-Nb-Zr system used for biomedical applications.