ROLE OF BONE SUBSTITUTES

Approximately 500 million years ago, the Paleozoic era heralded an evo lutionary marvel: the skeleton, Unique to this evolutionary developmen t was the capacity for regeneration: the physiologic renewal of embryo logically derived tissue, Many of the cellular and molecular component s for bone regeneration have been identified (bone morphogenetic prote ins), and their therapeutic manipulation will become common clinical p ractice, Moreover, synthetic materials produced in the laboratory and novel bone derivatives will be used to exploit the skeleton's capacity to regenerate and repair, The concept of repair may be viewed as the restoration of form and function to deficient osseous tissue, Material s that provoke repair can be categorized broadly as bone substitutes, In this review bone substitutes are grouped into 2 categories, polymer s and ceramics, and each is subclassifled as biodegradable or nonbiode gradable. Examples of these materials are provided as well as some of their liabilities and virtues.