In vitro toxicity testing of implantation materials used in medicine: Effects on cell morphology, cell proliferation and DNA synthesis.

Modern medicine depends in many cases on implantation of xenobiotic materials into the human body. Toxicity evaluation of these materials (plastic, metal alloy, ceramics) is rather difficult, mainly because of their intricate chemical nature and insolubility. There are two main approaches to the toxicity testing of implantation materials: cells are either placed in direct contact with materials to be tested or are treated with eluates made from the materials under study. Cell proliferation and cell morphology were chosen as principal endpoints in general cytotoxicity testing. Two modified methods were used as a measure of cell proliferation: first, direct cell counting within defined areas during subsequent time intervals; secondly, determination of DNA synthesis based on incorporation of radiolabelled thymidine. Prelabelling with [(14)C]thymidine was used and [(3)H]thymidine was applied after treatment with the substance tested. Changes in the (3)H:(14)C ratio are proportional to changes in DNA synthesis. The potential usefulness of all three methods was evaluated by testing a new bioactive ceramic (BAS) to be used in orthopaedics, and a new polymer, EVICROL ESTHETIC, to be used in dentistry. Similar results were obtained with all three methods.