Adjunctive Treatment Effect of Non-Thermal Atmospheric Pressure Plasma in Periodontitis-Induced Rats

Background/Objectives: As non-thermal atmospheric pressure plasma (NTP) is known to have advantages in application in the medical field, we consider its applicability to periodontitis, a representative chronic inflammatory disease. The purpose of this study was to evaluate the effect of NTP in inhibiting the progression of periodontitis in a rat model when additionally used in scaling and root planing (SRP). Methods: To induce experimental periodontitis in 20 rats, ligatures were placed in the maxillary second molar and lipopolysaccharide from Porphyromonas gingivalis was injected around the teeth. Then, NTP treatment was performed for 2 or 5 min, together with scaling and root planing (SRP). To evaluate alveolar bone loss, micro-computed tomography (micro-CT) analysis and hematoxylin-eosin (H-E) staining were performed. Tartrate-resistant acid phosphatase (TRAP) analysis was performed to compare the number of osteoclasts, while immunohistochemistry (IHC) analysis was performed to determine the expression levels of receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG). Enzyme-linked immunosorbent assay (ELISA) analysis was performed for the detection of cytokines (TNF-α, IL-1β, and IL-10) in tissues and sera. Results: When SRP was combined with NTP, alveolar bone loss was decreased, the number of osteoclasts and RANKL expression were decreased, OPG expression was increased, and pro-inflammatory cytokine (TNF-α and IL-1β) levels were significantly decreased. Compared with the NTP treatment for 2 min, when treated for 5 min, less alveolar bone loss, fewer osteoclasts, a lower RANKL expression level, and a higher OPG expression level were observed. Conclusions: This study evaluated the adjunctive treatment effect of NTP in periodontitis-induced rats. Based on the results of this study, we suggest that supplemental NTP treatment may be a good option for non-surgical periodontal treatment; however, further studies are needed to elucidate the mechanism through which NTP suppresses periodontal inflammation.