Tissue response to intraosseous implants in albino rats

The purpose of this study was to determine changes in the soft or hard tissue surrounding isolated intraosseous implants. Implant screws were machined to uniform dimension from three gold-base alloys, two cobalt-base alloys, two stainless steel, and one platinum-iridium alloy. Adult, male albino rats (375 to 475 grams) were used. Perforations were made on the lateral aspect of the femur bone by means of friction-grip, round carbide burs, and screws were placed loosely in the perforations. Each animal received one implant only. Sham-operated controls were included for each group. Animals were killed at intervals of 1, 2, 3, 4, and 5 weeks. Longitudinal sections of the bone (with respect to the longitudinal axis of the implant) were stained with hematoxylin and eosin. A layer of connective tissue was present surrounding all implants. This capsule differed according to the type of metal and the duration of implantation. The formation and maturation of new bone appeared to have begun in the spiral adjacent to the periosteal end of the screw and to have proceeded toward the apex of the screw. Implants were completely encapsulated by newly formed bone at the end of the fourth week. The rate of formation of bone appeared to be higher in the control wounds. On the basis of the amount of bone formed around the implants, cobalt-base and stainless steel alloys were found to be more suitable for implantation than the other materials tested. © 1974