Radiopaque polymeric materials for medical applications. Current aspects of biomaterial research

The aim of this review is to give an overview and some insight into different radiopaque polymeric materials that are currently used as medical implants or inserts. The advantages and limitations of each radiopaque polymeric material are summarized. The main method used to make medical implants radiologically visible is based on blending polymers with conventional radiopaque agents, blends which usually are a physical mixture of acrylic derivatives and inorganic salts. Other methods reported involve either the formation of single-phase radiopaque polymer salt complexes somehow preventing the release of the radiopacifying element by entrapment of the complex in a crosslinked network, or radiopaque polymerized monomers characterized by a radiopacifying element associated with the monomer unit prior to polymerization. In the near future, research will certainly concentrate on biocompatible radiopaque polymers with covalently bound opaque elements leading to stable polymers with properties equivalent to the nonopaque, parent polymer.