Balancing Osseointegration and Infection Control: The Role of Titanium Surface Topography in Peri-Implant Biology

Background: Peri-implant infections remain a major cause of dental implant failure, largely due to bacterial adhesion and biofilm formation on implant surfaces. This study aimed to investigate how surface topography influences bacterial colonisation and osteoblastic response. Methods: Titanium discs with machined (Ma), sandblasted, large-grit, and acid-etched (SLA), and nanostructured (Nano) surfaces were prepared, sterilised, and seeded with pre-differentiated dental follicle mesenchymal stem cells. Co-cultures with Enterococcus faecalis (E. faecalis) and Streptococcus oralis (S. oralis) were established under CO2-free conditions, and cell–bacteria interactions were evaluated using fluorescence microscopy and quantitative image analysis. Results: Nano surfaces showed the highest osteoblastic adhesion and viability, while significantly reducing bacterial proliferation and biofilm formation compared with Ma and SLA surfaces. The sequence of colonisation influenced cell–bacteria dynamics, with early cell attachment limiting subsequent bacterial adhesion. Conclusions: Nano titanium surfaces may offer a dual benefit by promoting osseointegration while limiting bacterial adhesion. These findings support their potential use as surface modifications to reduce peri-implant infection risk and improve long-term implant success.