LONG-TERM OBSERVATION OF SUBCUTANEOUS TISSUE REACTION TO SYNTHETIC AUDITORY OSSICLE (APACERAM(R)) IN RATS

The present study evaluates histological characteristics of the soft t issue response to long-term implantation of Apaceram(R) discs composed of dense hydroxyapatite in rats. Discs were implanted into the subcut aneous tissue of 76 rats for six to 20 months. Decalcified histologica l sections stained with haematoxylin and eosin (H & E) and Mallory's a zan were examined. Different cell types surrounding implants were coun ted. The greatest proportion of macrophages was found at six months (1 3.5 per cent). This proportion gradually decreased to four per cent at 20 months. Small numbers of lymphocytes and foreign body giant cells were observed in every group, but neither neutrophils nor osteogenesis were observed in any specimens. Results of the present study and prev ious related studies indicate that despite reappearance of a small num ber of macrophages six months after implantation, Apaceram(R) is usefu l for reconstructive surgery.