Sputtered Nanoscale Calcium Phosphate Coating on Osseointegrated Implant Devices

Objective: The study was to test the hypothesis if sputtered nanoscale calcium phosphate (CaP) coating on titanium (Ti) implant devices will improve osseointegration when compared to machined microscale Ti. Methods: Nanoscale CaP coating was deposited on Ti disks and Ti dental implants using r.f. magnetron sputtering technique. Three groups of samples were prepared, including as-sputtered CaP (AS-CaP), sputtered CaP with a post-deposition heat-treatment at 600 degree C (SH-CaP) and machined Ti (MA-Ti) as controls. The coating was characterized using grazing angle x ray diffraction (XRD), scanning electron microscopy (SEM), contact angle measurement, profilometry and nano-scratch test. The coating also was evaluated with in vitro cell culture and in vivo dog femur models. The cell proliferation and differentiation on the coatings were measured within a 3-week incubation. The reverse torque and bone-implant contact length were also measured at 4 and 8 weeks after implantation. Results: The As-CaP was dense and consisting of approximately 100-200 nm grains. The SH-CaP consisted of 2-3 um grains. As-CaP exhibited significantly less total protein and ALP activity as compared to those on the Ti and SH-CaP. There were no significant differences in reverse torque between different groups after 4 and 8 weeks of implantation. Conclusions: Our study did not show that the nanoscale dense CaP coatings improved the osseointegration compared to the microscale dense Ti. The study was supported by the grant from Implant Dentistry Research and Education Foundation and International Collaboration Fund.