Experiment Study On The Antibacterial Effect Of Cold Atmospheric Plasma On Porphyromonas Gingivalis

Objective: Cold atmospheric pressure plasma(CAP)is a kind of ionized gas which can directly act on living tissue and has been widely used in the field of stomatology.The aim of this study was to describe the sterilizing effect of CAP on Porphyromonas gingivalis(P.g)and observe its effect on the ultrastructure of P.g.Methods:P.g on titanium surface was treated with air CAP source.According to the processing distance and processing time,the experimental group was divided into5mm30 s group,5mm60 s group,9mm30 s group and 9mm60 s group.The control group suffers no CAP treatment.After treatment,the quantity of P.g was observed by plate colony counting method,the morphology and distribution of P.g on the titanium surface of each group were observed by scanning electron microscope(SEM),and the ultrastructure of P.g was observed by transmission electron microscope(TEM).SPSS22.0 software package was used to analyze the experimental data of each group by single factor variance analysis and Q test,P<0.05 was considered statistically significant Results:(1)Plate colony count method:the number of bacteria decreased significantly after CAP treatment.The antibacterial effect was gradually increased with the increase of CAP treatment time and the decrease of treatment distance.The best antibacterial rate was achieved at 5mm60 s group.(2)Under scanning electron microscope: the bacteria were destroyed in varying degrees with the change of time and distance of CAP treatment,the bacteria in 5mm60 s group and 9mm60 s treatment group were dissolved and broken,and almost no complete bacterial morphology could be observed.The P.g in control group was still a complete short rod cell structure.(3)Under transmission electron microscope: with the change of processing time and distance of CAP,the bacteria are dissolved and ruptured in varying degrees.In both 5mm60 s group and 9mm60 s group,the cell wall and the cell membrane rupture,blurring and cytoplasm overflow,and the distorted and completely separated membrane structure could be observed.While in control group,the ultrastructure of P.g cells did not change significantly,and the structure of cell wall,cell membrane and cytoplasm structure were clear.Conclusions: The CAP could damage the ultrastructure of P.g and has a good antibacterial effect on P.g,which increases with increasing the treatment time and reducing the treatment distance in a certain range.