A subcutaneous tissue reaction in the early stage to a synthetic auditory ossicle (Bioceram®) in rats

The discs of synthetic auditory ossicle (Bioceram®), which are composed of aluminium oxide (Al2O3), were implanted subcutaneously in the interscapular region of 16 rats. The implanted specimens were removed at 1, 3, 7 and 14 days after implantation. The decalcified 6 μm thick sections were stained with H.E. and cell types around the implants were counted microscopically. We found that an acute inflammatory reaction occurred at one day, in which macrophages and neutrophils predominated, and almost disappeared at about 7 days after implantation. Fibrosis began to be observed at 3 days. During this early stage, foreign body giant cells were found in only one specimen at 3 days. These findings, in comparison with those in the controls, showed that the chemical irritation of Bioceram® to the subcutaneous tissue is slight, although the physical and/or chemical irritation of Bioceram® lasts continuously and induces fibrosis around the bioimplant. The results so far suggest that Bioceram® seems to be a satisfactorily biocompatible material, at least within the extent of 2 weeks.