Singlet oxygen generated by a new nonthermal atmospheric pressure air plasma device exerts a bactericidal effect on oral pathogens

Abstract

Oral diseases generally have certain bacteria associated with them. Non-thermal atmospheric pressure plasma (NTAP), generated at atmospheric pressure and room temperature, incorporates several molecules, including reactive oxygen species, that can inactivate various bacteria including oral pathogens. For this reason, several NTAP devices have been developed to treat oral diseases. Use of noble gases can enhance the bactericidal efficacy of NTAP, but this requires additional gas supply equipment. Therefore, a new NTAP device that employs ambient air as the working gas was developed. The device generates non-thermal atmospheric pressure air plasma. Here, the singlet oxygen (1 O 2) levels generated, their bactericidal effects on oral pathogens (Streptococcus mutans, Porphyromonas gingivalis, and Enterococcus faecalis), and the bacterial oxidative stress they imposed were measured. 1 O 2 generation in phosphatebuffered saline was assessed qualitatively using electron spin resonance (ESR) spectroscopy, and bactericidal efficacy was evaluated by counting of colony-forming units/mL. Bacterial oxidative stress was determined by measurement of hydrogen peroxide (H 2 O 2) and superoxide dismutase (SOD) activity. ESR indicated that the level of 1 O 2 increased significantly and time-dependently, and was inversely correlated with distance, but the bactericidal effects were correlated only with treatment time (not distance) as H 2 O 2 increased and SOD levels decreased, suggesting that the new device has potential applicability for treatment of oral disease.

Low-Temperature Plasma as an Approach for Inhibiting a Multi-Species Cariogenic Biofilm

“…Argon gas was the choice for the plasma-generating device; the distance from the plasma outlet to the sample surface was 10 mm; and the biofilms were treated for 30 s, 60 s, and 120 s. Hirano et al [52] analyzed the effect of a plasma-generating laboratorydeveloped device, which was different from the one used in our work, on free-floating planktonic cells. Bacterial cell suspensions containing 10 7 CFU/mL of either S. mutans, Porphyromonas gingivalis, or E. faecalis were treated.…”

“…The gas used in their study was compressed air with a pulsed energy generator. The distances of 1 mm, 3 mm, and 5 mm were set between the plasma outlet and the single-species S. mutans biofilm surface, and the samples were treated for 1, 3, 5, and 7 min [52].…”

Opinions from five oral specialists on 3D printing in the challenge of customized oral healthcare. What can plasma technology bring?

“…Also, oral microorganisms' adhesion can be reduced by CAP application. [26,27] Thus, the materials used in 3D printing could be activated by plasma and plasma technology could render these biomaterials bioactive. [28,29] The modification of the gas or the parameters of the plasma induces the modification of the physicochemical species produced and therefore of the properties of the plasma.…”

Cold atmospheric pressure plasmas applications in dentistry

“…[86] What's more, the in vitro antibacterial effects of CAP on the common species including Streptococcus oralis (S. oralis), Enterococcus faecalis (E. faecalis), Actinomyces naeslundii (A. naeslundii), Veillonella parvula (V. parvula), and Fusobacterium nucleatum (F. nucleatum) has been demonstrated. [81,87,88,95] Nevertheless, there are unavoidable limitations of CAP application on biofilm inhibition. First, penetration of CAP is prevented by the matrix in the thick biofilms, leading to incomplete removal of bacteria at the bottom of the biofilms.…”

“…[ 86 ] What's more, the in vitro antibacterial effects of CAP on the common species including Streptococcus oralis ( S. oralis ), Enterococcus faecalis ( E. faecalis ), Actinomyces naeslundii ( A. naeslundii ), Veillonella parvula ( V. parvula ), and Fusobacterium nucleatum ( F. nucleatum ) has been demonstrated. [ 81,87,88,95 ]…”