Exploring the Broad Spectrum of Titanium–Niobium Implants and Hydroxyapatite Coatings—A Review

Tooth loss replacement using dental implants is becoming more frequent. Traditional dental implant materials such as commercially pure titanium and titanium aluminum vanadium alloys have well-proven mechanical and biological properties. New titanium alloying metals such as niobium provide improved mechanical properties such as lower elastic modulus while displaying comparable or even better biocompatibility. Hydroxyapatite coatings are a well-documented and widely used method for enhancing dental implants’ surface characteristics and properties and could provide a useful tool for further enhancing titanium–niobium implant properties like osteointegration. Among several coating techniques, physical deposition methods and, in particular, vapour deposition ones are the most used due to their advantages compared to wet deposition techniques for hydroxyapatite coating of metallic surfaces like that of dental implants. Considering the scarcity of data concerning the in vivo evaluation of titanium–niobium biocompatibility and osteointegration and the lack of studies investigating coating these new proposed alloys with hydroxyapatite, this review aims to further knowledge on hydroxyapatite-coated titanium niobium alloys.