Modulation of osteoblast behavior on TiN _x O _y coatings by altering the N/O stoichiometry while maintaining a high thrombogenic potential

Introduction Titanium nitride oxide (TiN _x O _y ) coatings are known to stimulate osteoblast proliferation and osseointegration when compared to microrough titanium implants. The objectives of the present study were to determine whether the beneficial effects of TiN _x O _y coatings observed with implant osseointegration are dependent on N/O stoichiometry, with the final goal of optimizing these benefits. MMs TiN _x O _y coatings with various N/O compositions were deposited on microrough titanium plates (Ti-SLA, 11 × 11 mm). Human primary osteoblast (hOBs) proliferation and gene expression were analyzed for a time course of three weeks, with or without additional stimulation by 1.25 (OH) ₂ vitamin D3 100 nM. Platelet adhesion/activation and thrombin generation were also assessed. Results hOBs proliferation gradually increased with the amount of oxygen contained in the coatings. The effect was observed from day 7 to reach a maximum at day 10, with a 1.8 fold increase for the best coating as compared to Ti-SLA. SEM views indicated that cells adhered, spread and elongated faster on oxygen-rich TiN _x O _y films, while the differentiation process as well as the thombogenic potential was not affected. Conclusions The effect of TiN _x O _y coatings on osteoblast is dependent on their chemical composition; it increases with the amount of oxygen. TiN _x O _y coatings may act as a catalyst for cell-adhesion and proliferation early after seeding. In contrast, thrombogenicity of Ti-SLA surface is not affected by TiN _x O _y application.