Oxidized Titanium Screws Coated with Calcium Ions and Their Performance in Rabbit Bone
Young-Taeg Sul, DDS, PhD, Carina B. Johansson, PhD, Tomas Albrektsson, MD, PhD, ODhc
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.