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S E C T I O N

I.1Properties of Materials

CHAPTER I.1.1 INTRODUCTION: PROPERTIES OF MATERIALS: THE PALETTE OF THE BIOMATERIALS ENGINEER

Jack E. LemonsUniversity Professor, Schools of Dentistry, Medicine and Engineering, University of Alabama at Birmingham, Birmingham, AL, USA

The platform, or palette, upon which the biomaterials engineer arranges information into parts for subsequent blending, let us say an art of biomaterials science, has expanded and evolved significantly in content over past decades. The depth and breadth of what is now included on this palette goes well beyond expectations expressed by founding members of the Society for Biomaterials in the late 1960s and early 1970s.

The science in biomaterials science has included fundamental aspects of physical, mechanical, chemical, electrical, and biological (compatibility) properties of the synthetic and natural origin biomaterials per se. Also, the methods for measuring and analyzing properties are equally applicable to the structures of the biological host. Following the recognition of the need by found-ers of the discipline in the 1960s, one focus has been the fundamental structure versus property relationships leading to in vivo biocompatibility. These relationships, and the supporting scientific information, have changed with time and experience, especially as the biological and clinical disciplines have also evolved. For example, considerations for biocompatibility are very different for biomaterials listed within biotolerant (called inert), sur-face bioactive (intended), and biodegradable categories. This shift of emphasis is reflected in the progression of content of the first three editions of this book. For exam-ple, initial considerations focused on materials were based primarly on substances of the metallics, ceram-ics, and polymerics available within various industrial applications. Thus, the emphasis in the first edition was on materials of synthetic origin and the science leading

to biomaterials. The second and third editions represent the transitions from combination products to the new areas of bioactives and biodegradables. Thus, as an inte-grated, comprehensive, and authoritative text, this third edition reflects a broad range of biomaterials, and there-fore basic properties of new generation biomaterials for regenerative medicine.

Considering relationships between biomaterial and biological systems (the interface) and the dynamics of change from nanoseconds to years, we now better under-stand many mechanisms of interaction at the dimen-sions and concentrations used to describe interactions of atoms. It is also realized that all biomaterial and host environment interactions play a role in the broader aspects of biocompatibility, especially the functionality and longevity of implant devices. In this regard, Part I on “Materials Science and Engineering” emphasizes the more basic information on the bulk and surface proper-ties of synthetic and natural origin biomaterials. Critical aspects of constitution (chemistry) and structure ( nano-, micro-, and macrodimension) relationships are presented as related to properties of implant systems. These basic considerations from the nature (I.1.2), bulk (I.1.3), and surface (I.1.5) properties are also interrelated to biome-chanics (I.1.4).

In this edition, the concepts of property versus struc-ture relationships have been expanded in terms of the role of water in biomaterials (I.1.6). The science of inter-actions of synthetic and natural substances with water is recognized as one of the key aspects of surgical implant biocompatibilities. This is especially important for the evolution of the discipline to include new generation bio-materials needed for future implant applications.

In summary, the content of this Part I is broadly applicable to all parts of the third edition. Therefore, students are advised to always consider the basic prin-ciples as provided in this section. This has been rec-ognized as critical to the education of a specialist in biomaterials science leading to the selection of bio-materials for medical treatments utilizing all types of implant devices.