Tissue-Safe Low-Temperature Plasma Treatment for Effective Management of Mature Peri-Implantitis Biofilms on Titanium Surfaces

The unique screw-shape design and microstructure of implants pose a challenge for mechanical debridement in removing biofilms. Biofilms exhibit increased resistance to antimicrobials relative to single planktonic cells, emphasizing the need for effective biofilm removal during periodontal therapy for peri-implantitis treatment. To tackle this issue, our team evaluated the effectiveness of low-temperature plasma (LTP) for disinfecting titanium discs contaminated with multispecies biofilms associated with peri-implantitis, specifically focusing on biofilms matured for 14 and 21 days as well as biofilms that had formed on Straumann^Ⓡ Ti-SLA implants for 21 days. The biofilms included <i>Actinomyces naeslundii</i>, <i>Porphyromonas gingivalis</i>, <i>Streptococcus oralis</i>, and <i>Veillonella dispar</i>, which were grown in anaerobic conditions. These biofilms were subjected to LTP treatment for 1, 3, and 5 min, using distances of 3 or 10 mm from the LTP nozzle to the samples. Control groups included biofilms formed on Ti discs or implants that received no treatment, exposure to argon flow at 3 or 10 mm of distance for 1, 3, or 5 min, application for 1 min of 14 μg/mL amoxicillin, 140 μg/mL metronidazole, or a blend of both, and treatment with 0.12% chlorhexidine (CHX) for 1 min. For the implants, 21-day-old biofilms were treated with 0.12% CHX 0.12% for 1 min and LTP for 1 min at a distance of 3 mm for each quadrant. Biofilm viability was assessed through bacterial counting and confocal laser scanning microscopy. The impact of LTP was investigated on reconstituted oral epithelia (ROE) contaminated with <i>P. gingivalis</i>, evaluating cytotoxicity, cell viability, and histology. The results showed that a 1 min exposure to LTP at distances of 3 or 10 mm significantly lowered bacterial counts on implants and discs compared to the untreated controls (<i>p</i> < 0.017). LTP exposure yielded lower levels of cytotoxicity relative to the untreated contaminated control after 12 h of contamination (<i>p</i> = 0.038), and cell viability was not affected by LTP (<i>p</i> ≥ 0.05); thus, LTP-treated samples were shown to be safe for tissue applications, with low cytotoxicity and elevated cell viability post-treatment, and these results were validated by qualitative histological analysis. In conclusion, the study's results support the effectiveness of 1 min LTP exposure in successfully disinfecting mature peri-implantitis multispecies biofilms on titanium discs and implants. Moreover, it validated the safety of LTP on ROE, suggesting its potential as an adjunctive treatment for peri-implantitis.