Antimicrobial Efficacy of Nitrogen-Based Non-thermal Atmospheric Pressure Plasma Jet on Dental Biofilm

Biofilms on the tooth surface that are not removed regularly can lead to dental caries, gingivitis, or periodontal disease. Recently, numerous newly developed sterilization approaches and techniques based on nonthermal temperature gas plasma have been introduced in the medical field. This study investigates the influence of nitrogen-based nonthermal atmospheric pressure plasma jet (NTAPPJ) treatment on dental biofilms. To this end, oral biofilms were formed on saliva-coated hydroxyapatite (HA) disks in a batch culture at 37 °C under 5% CO2. HA disks were treated with NTAPPJ for 0, 30, 60, and 120 s. The antibacterial efficacy of the NTAPPJ treatment was determined from the number of colony forming units (CFU). Morphology and structural changes in the bacteria were examined using scanning electron microscopy. The surface characteristics of the HA disks were analyzed with X-ray photoelectron spectroscopy (XPS) and contact angle measurements. CFU were reduced, and biofilm morphology and structure were significantly affected by plasma treatment. XPS and contact angle analysis showed that the surface of plasma-treated specimens was significantly richer in hydroxyl groups and more hydrophilic relative to untreated samples. There was no significant difference between the cytotoxicity of the treated and untreated samples for each test group. Therefore, these results show that atmospheric plasma treatment is very effective for biofilm release, which makes NTAPPJ a promising technique for various clinical dental applications, including bacterial sterilization.