Bacterialkilling effect of atmospheric pressure n

Authors: Dexi Liu Zilan Xiong Tianfeng Du Xincai Zhou Yingguang Cao Xinpei Lu

Publish Date: 2011/12/16

Volume: 31, Issue: 6, Pages: 852-856

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Abstract

Recently plasma sterilization has attracted increasing attention in dental community for the atmospheric pressure nonequilibrium plasma jet APNPs which is driven by a kilohertz pulsed DC power may be applied to the dental and oral diseases However it is still in doubt whether APNPs can effectively kill pathogenic bacteria in the oral cavity and produce no harmful effects on normal oral tissues especially on normal mucosa The aim of this study was to evaluate the bacterialkilling effect of APNPs in the biofilms containing a single breed of bacteria Porphyromonas gingivalis Pg and the pathological changes of the oral mucosa after treatment by APNPs Pg was incubated to form the biofilms in vitro and the samples were divided into three groups randomly group A blank control group B in which the biofilms were treated by APNPs the setting of the equipment 10 kHz 1600 ns and 8 kV group C in which the biofilms were exposed only to a gas jet without ignition of the plasma Each group had three samples and each sample was processed for up to 5 min The biofilms were then fluorescently stained observed and photographed under a laser scanning confocal microscope In the animal experiment six male Japanese white rabbits were divided into two groups randomly n=3 in each group in terms of the different posttreatment time 1day group and 5day group The buccal mucosa of the left side and the mucosa of the ventral surface of the tongue were treated by APNPs for 10 min in the same way as the bacterial biofilm experiment in each rabbit and the corresponding mucosa of the other sides served as normal control The clinical manifestations of the oral mucosa were observed and recorded every day The rabbits were sacrificed one or five days after APNPs treatment The oral mucosa were harvested and prepared to haematoxylin and eosinstained sections Clinical observation and histopathological scores were used to assess mucosal changes The results showed the obvious Pg biofilms were formed at 10 days and most of the bacteria in groups A and C were alive under a laser scanning confocal microscope but the bacteria in the group B were almost all dead In animal experiment no ulcers anabrosis and oral mucositis were found in both the 1day and 5day groups The average mucous membrane irritation index was −083 and −067 in the 1day and 5day groups respectively suggesting that no intense mucosal membrane irritation responses occurred It was concluded that APNPs could effectively kill Pg in the biofilms and did not cause any pathological changes in the normal mucosa suggesting that the plasma jet APNPs may be applied to oral diseases as a novel sterilization device in the future

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