Histological, histocytochemical and ultrastructural study on the effects of surface charge on bone formation in the rabbit mandible

The osteogenic potential of different surface charges was studied by implanting uncharged, negatively charged and positively charged Sephadex beads subperiosteally on the buccal aspect of the mandible. The implant sites were examined 1, 2, and 4 weeks later. New bone formation was observed around the positively charged beads at 2 weeks. An amorphous collagen-free layer seen around the beads consisted of anionic substances and contained needle-like crystals. Tartrate-resistant acid phosphatase-positive, multinucleated giant cells, which had typical fine structural characteristics of osteoclast-like ruffled borders and a clear zone, were observed on the surface of positively charged beads, with osteoblastic cells juxtaposed to them. Bone formation was still going on at 4 weeks in this group. Around the uncharged or negatively charged beads, new bone formation and osteoclast-like cells were not observed at any time. The findings suggest that the surface charge of implant materials has a definite influence on the differentiation of osteoclastic cells and subsequent occurrence of osteoblastic cells leading to formation of bone.