Photocatalytic enhancement of antibacterial effects of photoreactive nanohybrid films in an in vitro Streptococcus mitis model.

Objective: Bacterial adhesion and colonization on implanted devices are major etiological factors of peri-implantitis in dentistry. Enhancing the antibacterial properties of implant surfaces is a promising way to reduce the occurrence of inflammations. In this in vitro study, the antibacterial potential of two nanocomposite surfaces were investigated, as possible new materials for implantology.

Material And Methods: The structural and photocatalytic properties of the TiO and Ag-TiO (with 0.001 wt% plasmonic Ag content) photocatalyst containing polymer based composite layers were also studied and compared to the unmodified standard sandblasted and acid etched Ti discs (control). The presence of visible light induced reactive oxygen species was also verified and quantified by luminol based chemiluminescence (CL) probe method. The discs with adhered Streptococcus mitis were illuminated for 5, 10 and 15 min. The antibacterial effect was determined by the metabolic activities of the adhered and proliferated bacterial cells and protein assay at each time point.

Results: The Ag-TiO containing surfaces with obvious photocatalytic activity eliminated the highest amount of the metabolically active bacteria, compared to the control discs in the dark, after 15 min illumination.

Conclusions: The plasmonic Ag-enhanced and illuminated surface exhibits significantly better antibacterial activity under harmless visible light irradiation, than the control Ti or TiO containing copolymer. The studied surface modifications could be promising for further, more complex investigations associated with dental research on infection prevention in connection with oral implantation.