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Materials and devices intended for end-use applications as implants and medical devices must be evaluated to determine their biocompatibility potential in contact with physiological systems. The use of standard practices of biological testing provides a reasonable level of confidence concerning the response of a living organism to a given material or device, as well as guidance in selecting the proper procedures to be carried out for the screening of new or modified materials. This article presents results from cytotoxicity assays of cell culture, skin irritation, and acute toxicity by systemic and intracutaneous injections for powders, ceramic bodies, and extract liquids of hydroxyapatite (HA), calcia partially stabilized zirconia (ZO), and two types of zirconia-hydroxyapatite composites (Z4H6 and Z6H4) with potential for future use as orthopedic and dental implants. They indicate that these materials present potential for this type of application because they meet the requirements of the standard practices recommended for evaluating the biological reactivity of ATCC cell cultures (CCL1 NCTC clone 929 of mouse connective tissue and CCL 81 of monkey connective tissue) and animals (rabbit and mouse) with direct or indirect patient contact, or by the injection of specific extracts prepared from the material under test. In addition, studies involving short-term intramuscular and long-term implantation assays to estimate the reaction of living tissue to the composites studied, and investigations on long-term effects that these materials can cause on the cellular metabolism, are already in progress.

The technique of the rotating disk was used to measure the zeta potential of planar surface of different materials, like minerals, polymeric materials, and films of paints and particles. This technique is simple and reliable from the experimental point of view. The results are discussed concerning the principles of the technique, the rheological characteristics and the applications of these materials.

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Hybrids of poly(2-hydroxyethyl methacrylate) (PHEMA), a polymer that has been employed in a wide variety of biomedical applications, and silica-gel, which exhibits a well-known bioactivity, were produced. The obtained hybrids were characterized and their in vitro ability to induce the formation of a calcium phosphate layer on the surface was evaluated. The surface area of hybrids decreased with increasing amounts of PHEMA so that hybrids with more than approximately 40% PHEMA are virtually non-porous. All hybrids induced the formation of a calcium phosphate layer on their surfaces when soaked into simulated body fluid. The induction time and the morphology of the apatite layer varied according to the polymer content.

In this work we analyzed the "residual" performance of Portland cement concretes heat-treated at 600 °C after cooling down to room temperature. Concretes with characteristic compressive strength at 28 days of 45 MPa and of 60 MPa were studied. The heat-treatment was carried out without any imposed load. We measured the residual compressive strength and modulus of elasticity. The geometry of the structure was described by mercury intrusion porosimetry and nitrogen sorption tests. We observed a decrease of residual compressive strength and modulus of elasticity, with the raise of heat-treatment temperature, as a result of heat-induced material degradation. The results also indicated that the microstructural damage increased steadily with increasing temperature. Based on the results of this experimental work we concluded that residual mechanical properties of concrete are dependent of their original non heat-treated values