Compound bone cement on a PMMA base with an additive of bioactive glass ceramic particles in different portions and different particle sizes are tested in animal experiments. The tissue reactions to extracorporal polymerized specimens and to in situ polymerized specimens are observed. The experiments with an implantation period up to six months demonstrate a tight bonding between the newly formed osseous tissue and the glass ceramic particles at the interface. The inflammatory reactions in the vicinity of the implant are small. It is the objective of the investigations to improve the adherance of the bone cement at the interface to achieve a more durable anchorage of bone cement in the tissue.
The biocompatible and bioactive glass-ceramic material Ceravital, which has been developed, can be adapted to the physiological conditions of the organs by apropriately monitoring its chemical composition. The material exhibits a remarkable long-term stability in in vitro solubility tests and when used as implants in animal experiments.
The effect of pulverized plastic and glass-ceramic materials (methylmetacrylate, MMA), which are used as implantation materials in surgical medicine, on cell growth, DNA synthesis rate (adjudged by incorporation of 3H-thymidine into DNA), glucose consumption and lactate production (glycolytic rate) was studied in asynchronous monolayer cultures of rather fast proliferating Ehrlich ascites tumor cells and rather slowly proliferating diploid human fibroblasts. Exposure of Ehrlich ascites cells to high concentrations (2 mg/ml; 10 ml medium per culture) of ceramic or plastic material resulted in a gradual inhibition of cell growth and DNA synthesis rate. Protein synthesis, as measured by the incorporation of 3H-leucine, was somewhat less affected than DNA synthesis. Also, the glycolytic rate of Ehrlich ascites cells was slightly but significantly decreased in the presence of 2 mg/ml ceramics or MMA. Exposure of Ehrlich ascites cells to 0.2 or 0.02 mg/ml over a period of 46 h revealed none or only slight inhibitory effects on growth, DNA synthesis or glycolytic rate. On the other side, growth, DNA synthesis and glycolytic rates of human fibroblasts were nearly not affected by the presence of the same concentrations (up to 2 mg/ml, incubation period: 92 h) of pulverized ceramic or plastic material (MMA). It is suggested that this differential cellular sensitivity might be related to differences in the binding (to the cell surface) or uptake of these substances and possibly to differential intracellular lysosomal activation.
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