CERAMICS - PAST, PRESENT, AND FUTURE

The selection and application of synthetic materials for surgical impl ants has been directly dependent upon the biocompatibility profiles of specific prosthetic devices. The early rationale for ceramic biomater ials was based upon the chemical and biochemical inertness (minimal bi oreactivity) of elemental compounds constituted into structural forms (materials). Subsequently, mildly reactive (bioactive), and partially and fully degradable ceramics were identified for clinical uses. Struc tural forms have included bulk solids or particulates with and without porosities for tissue ingrowth, and more recently, coatings onto othe r types of biomaterial substrates. The physical shapes selected were a pplication dependent, with advantages and disadvantages determined by: (1) the basic material and design properties of the device construct; and (2) the patient-based functional considerations. Most of the cera mics (bioceramics) selected in the 1960s and 1970s have continued over the long-term, and the science and technology for thick and thin coat ings have evolved significantly over the past decade. Applications of ceramic biomaterials range from bulk (100%) ceramic structures as join t and bone replacements to fully or partially biodegradable substrates for the controlled delivery of pharmaceutical drugs, growth factors, and morphogenetically inductive substances. Because of the relatively unique properties of bioceramics, expanded uses as structural composit es with other biomaterials and macromolecular biologically-derived sub stances are anticipated in the future.