The project investigated a novel plasma‑jet system for the disinfection of dental implant surfaces and peri‑implantitis treatment. The study was conducted as an in‑situ clinical trial at a university dental clinic, following a rigorous informed‑consent process that covered study background, participation steps, potential risks, data protection, and the right to withdraw. Participants were adults aged 18 to 60 with at least 20 natural teeth, good oral hygiene, and no systemic disease. Exclusion criteria eliminated subjects with periodontal disease, recent antibiotic use, pregnancy, or excessive alcohol consumption. A total of 24 volunteers were enrolled after a risk‑benefit analysis that reassessed COVID‑related exposure risks once the pandemic subsided.

The plasma‑jet device comprises a base station, a handpiece, and a mono‑ or bipolar micro‑nozzle. Development followed European Medical Device Regulation Annex I, targeting a Class IIa CE certification. The team identified relevant standards for biocompatibility, electrical safety, and cleaning, then stratified technical challenges into test benches for gas flow, electrical insulation, nozzle arcing, cable shielding, and connector integrity. Over the course of the project, 10 functional prototypes and more than 26 pre‑versions were produced, with each iteration validated against the applicable standards. The handpiece was integrated into a modified 3‑D printer that moved the nozzle in a 1 mm spaced, 45 mm line at 60 mm min⁻¹, creating a plasma track on agar plates. Microscopic imaging showed that the plasma reduced bacterial colonies by up to six log‑folds, leaving a clear, bacteria‑free zone wider than the 0.8 mm nozzle diameter. Life/dead staining confirmed the near‑complete inactivation of surface bacteria on treated samples.

For peri‑implantitis relevance, titanium discs (5 mm × 1 mm) were prepared by sandblasting, acid etching, and rinsing, then inoculated with Enterococcus faecalis biofilm in a custom bioreactor for five days. The plasma‑jet was applied to the discs, and subsequent colony‑forming unit counts revealed a reduction of more than 99.9 % compared with untreated controls. The device’s pulsed high‑voltage operation prevented overheating of the target tissue, addressing the primary safety concern for plasma‑based medical devices.

Usability testing assessed the interface between clinician and device. Operators reported that the handpiece was lightweight, the nozzle alignment was intuitive, and the overall workflow integrated smoothly into routine implant maintenance procedures. The study also documented the device’s performance under realistic clinical conditions, confirming that the plasma‑jet could be applied directly to implant surfaces without compromising surrounding tissues.

Collaboration was led by the Institute for Microsystems Technology (IMTEK) and the Clinic for Dental Conservation, with a dedicated 3‑D printing facility ensuring reproducible nozzle trajectories. Straumann GmbH supplied reference titanium plates for comparative analysis. The project was funded by a national research grant, and the ethics committee of the Medical Faculty at Albert Ludwig University Freiburg approved the protocol (vote 516/12). The original timeline was extended by three months to accommodate pandemic‑related delays, and the project plan was revised accordingly. The final technical documentation, incorporating pre‑clinical and clinical data, positions the plasma‑jet system for CE certification and subsequent market entry as a Class IIa medical device for peri‑implantitis therapy.