Oxidized Titanium Screws Coated with Calcium Ions and Their Performance in Rabbit Bone

Purpose: The aim was to answer a fundamental question: Do the chemical properties of titanium implants influence osseointegration? Materials and Methods: Screw-type implants produced of turned commercially pure (grade 1) titanium (controls) and electrochemically calcium-deposited titanium implants (Ca test implants) were placed in the tibiae and femora of a total of 10 mature New Zealand white rabbits. The macro arc oxidation method was applied for Ca implants. Surface oxides were characterized with different analytic techniques, including x-ray photoelectron spectroscopy, auger electron spectroscopy, scanning electron microscopy, thin-film x-ray diffractometry, and TopScan 3D. The bone response was evaluated by biomechanical tests, histology, and histomorphometry. Results: After a follow-up period of 6 weeks, test Ca implants showed a significant increase in mean peak removal torque (P = .0001) and in the histomorphometric measurement of bone-to-metal contact around the implants (P = .028) in comparison to controls. In addition, more mature mineralized bone was observed adjacent to test Ca implants compared to controls, as evaluated on 10-µm undecalcified, toluidine blue-stained, cut, and ground sections. Discussion: The potential role of surface Ca chemistry to a superior bone response is discussed with specific reference to interaction with Ca±binding proteins and function as binding sites of calcium phosphate mineral. Conclusion: The present results suggest that the surface chemical composition of titanium implants is of great importance for the bone response. Ca ion-deposited titanium implants showed fast and strong osseointegration in the rabbit bone model.