Chapter 1a Metallic Biomaterials: Introduction

Abstract

Metallic biomaterials are one of the most commonly used biomaterial groups along with ceramics, synthetic polymers, and naturally derived products. The utility of these metallic materials is based largely on the formation of a thin but protective oxide layer. The oxide layer forms upon exposure to oxygen and re-forms within milliseconds after damage [1]. This layer reduces corrosion in vivo, one of the major requirements of a robust biomaterial. The other requirements include biotolerability, bioadhesion, biofunctionality (bioactivity), and processability. In practice each metal or alloy, i.e., titanium alloys, stainless steel, and Co-Cr alloys, has their own advantages for different applications based on mechanical, chemical, and biofunctional properties. Generally, metallic biomaterials are used for structural applications such as implants, pins, and bone scaffolding due to their excellent mechanical properties such as Young’s modulus, tensile strength, ductility, fatigue, and wear resistance. However, they can be used for unloaded, purely functional devices such as cages for pumps, valves, and heart pacemakers. The first generation of metallic biomaterials was designed for minimal toxicity. The second generation has been designed for functionality at both at the mechanical and molecular level to enhance integration of the material into the biological environment and increase longevity of the implant. The third generation has focused not only on functionality but also on regeneration of the surrounding tissue in conjunction with the bioactive material [2]. In the following chapters the metallic biomaterials are characterized in terms of their composition, physical and mechanical properties, and their corrosion and biological behavior.