Japan's largest platform for academic e-journals: J-STAGE is a full text database for reviewed academic papers published by Japanese societies

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 (¹O₂) levels generated, their bactericidal effects on oral pathogens (Streptococcus mutans, Porphyromonas gingivalis, and Enterococcus faecalis), and the bacterial oxidative stress they imposed were measured. ¹O₂ 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 (H₂O₂) and superoxide dismutase (SOD) activity. ESR indicated that the level of ¹O₂ increased significantly and time-dependently, and was inversely correlated with distance, but the bactericidal effects were correlated only with treatment time (not distance) as H₂O₂ increased and SOD levels decreased, suggesting that the new device has potential applicability for treatment of oral disease.

Chemomechanical procedures can be used to eliminate bacteria from root canals. However, detectable bacteria sometimes remain because of the complexity of the root canal system. Endodontic passive ultrasonic irrigation (PUI) with hydrogen peroxide (H₂O₂) may be a promising option for increasing bactericidal hydroxyl radical (HO^•) generation. In this in vitro experiment, we examined the effects of HO^• generated using PUI and a low concentration of H₂O₂. An ultrasonic tip was submerged in 0.45 mol/L (1.5%) H₂O₂ in a microfuge tube. H₂O₂ was activated by an ultrasonic unit, the tip of which was kept centered in the tube, to mimic PUI. HO^• generation was detected by electron spin resonance spectroscopy. An Enterococcus faecalis suspension in H₂O₂ was then preparedand activated as described above. Bactericidal effects were assessed by viable counting. Two-way analysis of variance and Tukey’s test were used to assess the statistical significance of differences among groups (P < 0.05). HO^• generation and bactericidal activity were significantly increased by PUI in H₂O₂ in a time-dependent manner and were significantly higher than with H₂O₂ alone or with PUI in a Tris-HCl suspension. These results suggest that PUI in the presence of a low H₂O₂ concentration is a promising new disinfection strategy. (J Oral Sci 56, 35-39, 2014)

Japan's largest platform for academic e-journals: J-STAGE is a full text database for reviewed academic papers published by Japanese societies

Japan's largest platform for academic e-journals: J-STAGE is a full text database for reviewed academic papers published by Japanese societies