Effects of oxygen plasma treatment on surface properties, osteoblastic response, and bacterial behavior of implant–prosthetic materials

Objective: A major goal in oral implantology is to develop materials that enhance osseointegration while reducing bacterial colonization, thereby preventing peri-implant diseases. Materials and Methods: This study evaluated the effects of oxygen plasma treatment on materials commonly used in implant–prosthetic systems, including titanium, cobalt–chromium alloy, zirconia, and porcelain. Surface roughness was assessed by confocal microscopy. Plasma treatments were performed at 60 W for 60 s. Hydrophilicity was evaluated by contact angle measurements immediately after treatment, and surface energy along with its dispersive and polar components was determined. Human osteoblastic SaOS-2 cells were cultured on each material, and cell adhesion and mineralization were assessed by alkaline phosphatase and osteocalcin expression after 1, 3, 7, and 21 days. In addition, the metabolic activity of seven common oral biofilm-forming bacteria was evaluated after 3, 7, and 21 days: aerobic species ( Streptococcus gordonii , Staphylococcus aureus , Pseudomonas aeruginosa ) and anaerobic species ( Streptococcus sanguinis , Porphyromonas gingivalis , Fusobacterium nucleatum , and Aggregatibacter actinomycetemcomitans ). Results: No significant differences in surface roughness were observed among the materials. Oxygen plasma treatment induced a marked reduction in contact angle in all materials, with titanium exhibiting superhydrophilic behavior. Surface energy increased significantly, particularly the polar component. Osteoblastic adhesion was minimal at early time points but increased markedly from day 3 onward, with peak alkaline phosphatase and osteocalcin levels observed at day 7, consistent with enhanced mineralization. This response correlated with the increase in surface energy, especially its polar component. While aerobic bacteria showed no significant reduction in colony-forming units or metabolic activity, anaerobic bacteria exhibited a significant decrease, likely due to increased surface oxygen content. Conclusion: Oxygen plasma treatment appears to be a promising approach for producing osteoconductive surfaces with a bactericidal effect, particularly against anaerobic bacteria, which are the most prevalent and pathogenic microorganisms involved in peri-implantitis. Clinical relevance: Given the growing clinical impact of peri-implantitis, this surface treatment strategy may play a decisive role in its prevention.