[Bioactive materials. A critical review]

The bioactive materials should be divided into osteoinductive and osteostimulative materials according to their effect in bone regeneration. Already this statement requires a definition of the words used, in order to assure a real discussion. By means of the recommendations for definitions this paper is a basis for those discussions. In order to classify the bioactive materials into types of materials the potential effect onto the bone regeneration process should be considered. On the other hand the synthetic or biological origin, and the physical or biochemical structure are of great significance. Beside the classification made by the above called criteria the types of materials with their advantages and disadvantages are described. In the following discussion some problems are described like the mechanical and chemical instability, the coating of metallic substrata, the sterilization and the possibilities for the analytic characterization of hydroxylapatite.