Biocompatibility evaluation of a new bioresorbable pin for membrane fixation

The aim of this study was to morphometrically analyze the tissue response to a customized pin obtained from devitalized bovine cortical bone (DBCB-pin) implanted in the subcutaneous tissue of rats, as well as to assess its microstructural aspect by scanning electron microscopy (SEM). The pins were implanted in the subcutaneous tissue of 20 rats, which were killed at 7, 14, 28 and 60 days (5 rats/period) after implantation. In the subcutaneous tissue, DBCB-pin promoted the formation of a fibrous capsule. At 7 days, capsule showed thickness of 70 ± 3.2 µm with higher density of newly formed capillaries and smaller density of collagen fibers. Between 14 and 60 days, more organized fibrous capsule exhibited smaller thickness (53 ± 5.5 µm) with higher density of fibroblasts and collagen fibers. In this period, a small and slow bioresorption of the DBCB-pin by macrophages and rare multinucleated giant cells without tissue damage was observed. The thickness of DBCB-pin resorbed was in mean only of 9.3 µm. During all experimental periods not occurred presence of immune reaction cells as lymphocytes and plasma cells. It was concluded that the pin derived from cortical bovine bone was well tolerated by subcutaneous tissue of rats and slowly resorbed could be an alternative material for membrane fixation in the guided tissue regeneration procedures.