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The In-Vitro Activity of a Cold Atmospheric Plasma Device

against Bacteria and Biofilms Associated with Periodontal or Peri-Implant Diseases

Authors: Jungbauer G., Favaro L., Müller S., Sculean A. & Eick S.

Publication: The In-Vitro Activity of a Cold Atmospheric Plasma Device Utilizing Ambient Air against Bacteria and Biofilms Associated with Periodontal or Peri-Implant Diseases, Antibiotics, 2022, 11(6), 752.

First published: https://www.mdpi.com/2079-6382/11/6/752

Summary:

Conventionally, the biofilm that develops in periodontal and peri-implant diseases is removed mechanically and treated with the addition of antibiotics. Due to the generally high use of antibiotics, a search for alternative treatment methods is necessary, with cold atmospheric plasma (CAP) showing promising potential as a new treatment method.

The aim of the in-vitro study was to investigate the effect of CAP on log10-step reduction of colony forming units (CFU) for different planktonic bacterial species. A treatment of multispecies biofilms also took place. Furthermore, the adhesion of gingival fibroblasts to dentin and titanium samples before and after plasma treatment was considered.

In the study, the piezobrush® PZ3 with Module Nearfield from relyon plasma, which was originally developed for non-medical applications, was used to generate CAP. Figure 1 shows the experimental setup. The plasma generated by a combination of Piezoelectric Direct Discharge and Dielectric Barrier Discharge was efficiently transferred to the grounded substrate. It reached a temperature of about 50 °C with a power consumption limited to 8 W, and the treatment distance was 2 mm.

Experimental assembly for the use of plasma against peridontal or peri-implant deseases
Figure 1. Experimental setup for the effect on planktonic bacteria and biofilms; DBD: Dielectric Barrier Discharge.

The bactericidal effect of CAP was investigated on a total of 11 bacterial species (including P. gingivalis, T. forsythia, and F. alocis).  Treatment times were 10, 30, 60, and 120 s. Compared to the untreated samples, a reduction of ≥3 log10 CFU could be detected in 10 of 11 bacterial species already after 30 s, and after 120 s the detection threshold of CFU could be undercut by 8 of the 11 species.

Number of colony-forming units, mass and metabolic activity of multispecies biofilms on dentin
Figure 2. (A) Colony forming units (CFU) counts, (B) mass and (C) metabolic activity of multispecies biofilms on dentin specimens and subsequent exposing of 30 s, 60 s and 120 s to cold plasma.

A strong influence on biofilms was also demonstrated by experiments with CAP. These were cultivated from the already investigated planktonic bacterial species. Figure 2 shows the test results on dentin. The number of CFU of the untreated biofilms was on average >8 log10, with a strong time-dependent decrease due to plasma treatment. After 120 s, a mean reduction of 2.43 log10 occurred. Biofilm mass did not change significantly by treatment, in contrast to metabolic activity. The latter was reduced by 95 % after 120 s of treatment. Analogously, similar results were obtained for titanium surfaces.

Number of gingival fibroblasts on dentin and titanium samples
Figure 3. Gingival fibroblast counts per mm2 on (A) dentin and (B) titanium specimens after pretreatment of 120 s of cold plasma.

Adhesion of gingival fibroblasts was observed mainly on titanium. In Figure 3, a significant increase in fibroblast concentration from 800 to 1200 cells/mm2 can be seen after a treatment period of 120 s in contrast to dentin, which underlines the potential of CAP for the pretreatment of titanium implants.

Conclusion:

In summary, it is shown that CAP, in this study generated by the piezobrush® PZ3, can be used as an effective bactericide. CAP has a strong inhibitory effect on biofilms and can be used as a pretreatment of titanium implants to enable faster fusion with jawbone material. In particular, the significant increase in fibroblast concentration promotes faster wound healing. The possibilities of treating periodontal and peri-implant diseases with CAP have been demonstrated with the promising results of this study and form the foundation for further investigations. 

You can read the complete publication here.

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