Bone healing at collagenated bicortically installed implants: an experimental study in rabbits.

PURPOSE: To study the healing at collagenated bicortically installed implants. METHODS: Twenty albino New Zealand rabbits were used for implant installation. Two implants with a double acid etched surface, coated with a collagen type I or left uncoated, were installed bicortically in the metaphysis and in the diaphysis of each tibia. Ten rabbits were euthanized after 2 weeks and ten after 6 weeks after installation. Ground sections were prepared for histological analyses that were performed both in the cortical layers and in the marrow regions. RESULTS: After 2 weeks of healing, highest amounts of new bone were found at the collagenated implants (43.2 +/- 6.0%) compared to the standard implants (33.9 +/- 6.1%; p = 0.022). After 6 weeks of healing, similar percentages of new bone were observed, being 51.8 +/- 7.3% and 50.9 +/- 9.6% (p = 0.678) for the standard and collagenated surfaces, respectively. CONCLUSIONS: A coated surface with collagen type I promoted bone apposition in the earliest periods of healing. However, the effect vanished over time so that similar results were obtained after 6 weeks of healing.