Spiked Titanium Nanostructures That Inhibit Anaerobic Dental Pathogens

Peri-implantitis is a devastating oral disease that has given rise to a demand for improved implantable dental biomaterials that can integrate well into the supporting bone as well as resist bacterial colonization. Recent research has demonstrated that nanostructured titanium may be well positioned to meet this demand. An abundance of literature has established the in vitro efficacy of nanostructured titanium against bacteria cultured aerobically, but its efficacy against anaerobic bacteria relevant to dental infections remains unknown. In the present study, we engineered sharp, spikelike nanostructures on commercially pure titanium surfaces using hydrothermal etching and challenged them with three clinically relevant, anaerobic dental pathogens: Streptococcus mutans, Fusobacterium nucleatum, and Porphyromonas gingivalis. Our results demonstrated that titanium nanostructures bearing sharp protrusions can be effective at eliminating bacteria in anaerobic conditions, in both single-species (up to ∼94% cell death) and dual-species (up to ∼70% cell death) models. Furthermore, surface modification greatly enhanced the efficacy of azithromycin treatment against anaerobic dental pathogens, compared to a control titanium surface. At 2× MIC (minimum inhibitory concentration), azithromycin eliminated 99.4 ± 0.3% of S. mutans on the nanostructured surface within 10 days, while only 26% of the bacteria were killed on the control surface. A similar result was observed for P. gingivalis. The data presented here serve as a promising foundation of knowledge on which to build a greater understanding of how nanostructured biomaterials can be effective in anaerobic environments such as that found in the oral cavity.