PRESENCE OF MULTINUCLEATED GIANT-CELLS AROUND MACHINED, SANDBLASTED AND PLASMA-SPRAYED TITANIUM IMPLANTS - A HISTOLOGICAL AND HISTOCHEMICALTIME-COURSE STUDY IN RABBIT

A histological and histochemical evaluation was conducted in rabbit to study the presence of multinucleated giant cells (MGCs) at the interf ace with machined, sandblasted and plasma-sprayed titanium implants. N o MGCs were observed, at any of the experimental times, around machine d and sandblasted titanium surfaces. MGCs were, on the contrary, prese nt at the interface with titanium plasma-sprayed implants at two weeks and at two months. At two weeks these cells were numerous, and in som e areas, particularly around the spires, tended to line almost all the implant perimeter surface. MGCs were present in large numbers where b one was present at the interface, while, on the contrary, where there was no newly formed bone, they tended to be fewer in number and smalle r in diameter. At four and eight weeks these cells tended to decrease in number. The histochemical staining for acid phosphatase (ACP) and a lkaline phosphatase (ALP) showed that MGCs were negative to ACP, while many ALP-positive osteoblasts, actively secreting osteoid matrix, wer e in close and tight contact with the MGGs. In no case was an inflamma tory infiltrate present in connection with the MGCs. The precise natur e of MGCs is still not clear, but our histological and histochemical r esults could point to a priming effect on the activity of the osteobla sts in a similar way to the supposed role of the osteoclasts. (C) 1996 Elsevier Science Limited