Modulation of osteoblast behavior on TiNxOy coatings by altering the N/O stoichiometry while maintaining a high thrombogenic potential.

Introduction: Titanium nitride oxide (TiNxOy) 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 TiNxOy coatings observed with implant osseointegration are dependent on N/O stoichiometry, with the final goal of optimizing these benefits. MMS: TiNxOy 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 TiNxOy films, while the differentiation process as well as the thombogenic potential was not affected.

Conclusions: The effect of TiNxOy coatings on osteoblast is dependent on their chemical composition; it increases with the amount of oxygen. TiNxOy 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 TiNxOy application.