Cold atmospheric plasma treatment of Porphyromonas gingivalis biofilms on titanium: antibacterial activity and gingival fibroblast responses

Cold atmospheric plasma (CAP) has been investigated as a potential approach for reducing biofilm-associated contamination on dental implant surfaces. This in vitro study evaluated the effects of CAP treatment on P. gingivalis biofilms formed on sand-blasted and acid-etched titanium disks and on human gingival fibroblast responses. P. gingivalis biofilms were formed on titanium disks for 5 days and exposed to CAP under predefined treatment conditions. Viable biofilm-associated bacteria were assessed by colony-forming unit analysis and live/dead staining. Optical emission spectroscopy and singlet oxygen sensor green fluorescence in phosphate-buffered saline were used to characterize plasma emissions and reactive oxygen species (ROS)-related signals. HGF-1 cell viability and intracellular ROS signals were evaluated after CAP exposure. Data were analyzed using one-way analysis of variance. CAP treatment reduced viable P. gingivalis biofilm-associated bacteria in a time dependent manner. Increased CAP exposure was associated with increased singlet oxygen sensor green (SOSG) fluorescence in phosphate-buffered saline. Longer CAP exposure was also associated with reduced HGF-1 viability and increased intracellular ROS signals. Under the present in vitro conditions, CAP treatment was associated with a reduction in viable P. gingivalis biofilm-associated bacteria on titanium surfaces and exposure time dependent HGF-1 responses. Further studies using multispecies biofilm models and clinically relevant experimental settings are required before clinical application can be inferred. • Cold atmospheric plasma (CAP) reduces viable P. gingivalis biofilm-associated bacteria on titanium surfaces. • CAP exposure is associated with increased ROS-related signals in aqueous solution. • CAP treatment produces a time-dependent reduction in viable bacterial counts. • Longer CAP exposure enhances antibacterial activity against P. gingivalis biofilms. • Prolonged CAP exposure increases intracellular ROS signals and reduces HGF-1 cell viability.