A histological investigation on early tissue response to titanium implants in a rat intramedullary model

Miniature grade 1 titanium screws were inserted in the tibias of 12 mature Wistar rats. Animals were sacrificed at 4, 7, and 21 days postimplantation. A combination of two morphological approaches was used to examine the tissue response to implants. One part of the prepared tissue specimens was routinely embedded in paraffin after a weak decalcification in EDTA. In this case, the implant was mechanically removed before embedding. The remainder of the specimens were embedded in polymethylmethacrylate resin, and ground sections were realized according to Donath's method. New bone formation occurred soon after implantation. Initially, on the fourth day, the presence of osteoid could be observed near the implant surface. On the seventh day, well-mineralized bone tissue was apposed directly on the implant surface. On the 21st day, the bone tissue became a highly organized lamellar bone.