Evaluation of In Vitro Biofilm Formation on Titanium Nitride Specimens

Objective: The purpose is to characterize the surface properties of specimens coated with titanium nitride (TiN) and to investigate the in vitro biofilm formation on TiN coated specimens.
Methods: Ti6Al4V specimens were coated with a <1 μm thick coating of TiN. Surface roughness, surface chemistry, and wettability were measured using 2D stylus profilometry, SEM/EDX, XPS, XRD, and contact angle analysis, respectively. The specimens were preconditioned with artificial saliva and thereafter incubated with a coculture of Streptococcus sanguinis, Actinomyces oris, and Porphyromonas gingivalis. Biofilm formation was evaluated with plate counts, qPCR, Live/dead, and Crystal Violet staining.
Results: Except for surface chemistry no significant differences regarding surface characteristics were found. EDX analysis showed oxygen content of the outermost part of the TiN coating, which was confirmed with XPS. XRD also showed the presence of TiNxOy compounds. Viable counts of the bacterial load on TiN after 24 hours incubation showed a log 2 reduction (p<0.05), but no difference was seen with qPCR.
Conclusion: TiN coatings are covered by a thin layer of TiNxOy. A biological effect could be shown based on bacterial viability. Its potential benefit for a dental application and the elucidation of the underlying mechanism require further investigation.