The aim of this study was to investigate the correlation between coating thickness and the crystal structure of physical-vapour-deposited (PVD) titanium dioxide coatings, and to evaluate their in vivo biocompatibility.Materials and methods
The PVD TiO2 coatings of different thickness were deposited on machined titanium grade 2 screw-shaped implants. Non-coated titanium implants were used as controls. Coating properties such as thickness, crystal structure, coating morphology and roughness were characterized.Materials and methods
Forty-eight implants were placed randomly into both tibias of 16 rats. The animals were euthanized 7 and 28 days postsurgery and block biopsies were prepared for histology, histomorphometry and SEM analysis.Results
The thicknesses of the PVDTiO2 coatings were 120 and 1430 nm respectively. Histologically, new bone formed on all implant surfaces. The mean percentage of newly formed bone in contact with the implant (BIC) was significantly higher at early healing time (7 days) for the 120 nm thick PVD coating (39 ± 14%) than for both the 1430 nm thick PVD coating (22 ± 10%) (P = 0.043) and the machined surface (22 ± 9%) (P = 0.028). This difference was no longer evident after 28 days (P = 0.867).Conclusion
Bone formation and bone-to-implant contact are achieved to the same degree for TiO2 surface modifications prepared by a PVD process as clinically used, machined titanium. Furthermore, a relatively thinner PVD coating promotes a higher degree of bone apposition shortly after implantation, thereby providing rationales for exploring the potential clinical use of these modifications.