Cold plasma: a novel approach to treat infected dentin-a combined ex vivo and in vitro study

The aim of this study was to evaluate the antimicrobial effect of cold plasma (CP) on infected dentin surfaces in vitro and ex vivo.

To examine the effect of cold plasma on root surfaces, 24 root surfaces were infected with Streptococcus mitis. Specimens were randomly divided into three groups: Within the control group (C), root surfaces were rinsed with NaCl; root surfaces in the second group were additionally scaled and root planed (SRP), and in the third group, root surfaces were rinsed, scaled, root planed, and in addition, CP was applied (SRP + CP). To examine the effect of CP on root caries lesions (RCLs), 16 freshly extracted teeth with symmetrical carious lesions were equally divided into two groups. In the control group, carious lesions were treated with chlorhexidine (CHX), whereas CHX was applied in conjunction with CP in the test group (CHX + CP). For microbiological analysis, dentin samples were serially diluted and CFU counts were estimated after 24 h of incubation.

Compared to C, mean CFU values for SRP and SRP + CP were significantly lower (p < 0.05). In addition, mean CFUs for SRP + CP were reduced to 0 and, therefore, significantly lower than SRP (2.98 log CFU/mL) alone (p = 0.000, Mann-Whitney U). Regarding RCLs, significantly lower mean CFU values were observed for CHX + CP when compared to CHX (4.45 vs. 2.67 log CFU/mL, p = 0.002, Mann-Whitney U test).

For disinfection of exposed root surfaces, the adjunctive application of CP is promising. In addition, the combined application of CHX + CP has the potential to disinfect root dentin surfaces.

It was shown that the combination of cold plasma with CHX is the best available option for the disinfection of root surfaces.