Tribocorrosion of Porous Titanium Used in Biomedical Applications

Abstract

Titanium and its alloys have become increasingly important in the dental and orthopedic fields due to its good machinability, high yield strength, good ductility, excellent corrosion resistance, and superior biocompatibility compared to other materials. However, an inherent drawback of using pure titanium and its alloys as implant material is the significant mismatch between the moduli of bone and titanium, resulting in the stress shielding effect, fibrous tissue ingrowth, and bone resorption, and therefore reducing the lifespan of the implant. Porous titanium is thus a suitable candidate as implant material due to its ability to be manufactured to a specific Young’s modulus—typically that of bone. Porous titanium has the unique advantage of allowing bone tissue ingrowth into the open space of the implants, thereby accelerating the osseointegration process. The human body as well as the oral cavity is a highly complex environment in which the simultaneous interaction between wear and corrosion, namely tribocorrosion, takes place. Thus, understanding these interactions is of great interest in order to characterize the degradation mechanisms of porous titanium materials used as implants. This paper reviews the state-of-the-art of porous titanium as a viable biomedical implant material. A significant part of this paper is focused on how porous titanium is manufactured and how its parameters are controlled. The following sections focus on the corrosion, wear, and tribocorrosion aspects of porous titanium implant materials. Finally, this review also determines the current limitations in the field and provides future directions in this field.