Bacteriostatic Effect Of Thymol On Porphyromonas Gingivalis And Germicidal Effect Of Photodynamic Therapy On Enterococcus Faecalis In Root Canals With Different Preparation

Obj ectives:In this study,the antibacterial effect of Thymol on Porphyromonas gingivalis,the effect on the formation of Porphyromonas gingivalis biofilm and the dispersion of mature bacterial biofilm were investigated.The antibacterial effect of Thymol on Porphyromonas gingivalis was evaluated by scanning electron microscope and laser confocal microscope.It is expected that Thymol can assist mechanical methods to control the local inflammation of chronic periodontitis.Methods:The minimal inhibitory concentration(MIC)and minimal bactericidal concentration(MBC)of P.gingivalis were determined by gradient concentration of thymol.After the selected thymol was co-cultured with bacteria,the protein content of the co culture medium of each drug concentration group was detected to evaluate the damage of thymol to the bacterial cell membrane.Crystal violet and MTT staining were used to evaluate the inhibition of drugs on the formation of bacterial biofilm and the dispersion of mature bacterial biofilm.The structure of bacteria was observed by scanning electron microscope.The effect of the drug on bacterial biofilm was evaluated by laser confocal microscopy after fluorescent staining.Results:The MIC of Thymol against P.gingivalis was 3125 μg/ml and the MBC was 12.5mg/ml.When the concentration of the drug was 12.5mg/ml(1.25%),it had the strongest damage to the bacterial cell membrane.The results of crystal violet and MTT staining showed that Thymol could effectively inhibit the formation of biofilm and promote its dissociation.Scanning electron microscope showed that the bacterial junction structure of the drug was destructive,and the dead and living bacteria in the biofilm were stained.Under laser confocal microscope,it was observed that with the increase of drug concentration,the proportion of dead bacteria in the group increased.Conclusions:Thymol has antibacterial effect on P.gingivalis,one of the main pathogens of chronic periodontitis,in order to provide more choices for clinical adjuvant treatment of chronic periodontitis.Objectives:After disinfection of root canals with photodynamic therapy,the best degree of root canal preparation,that is the best degree of mechanical preparation of root canals with the best disinfection effect was selected through the comparison of their antibacterial rates,to guide the clinical application of PDT in root canal preparation before disinfection.Methods:E.faecalis biofilm was built in the external orifice plate to verify the bacteriostatic and bactericidal effect of PDT on E.faecalis.Then E.f biofilm was built in the isolated root canal,and it was combined with mechanical preparation to different degrees with PDT root canal disinfection,and the degree of each root canal preparation was grouped to explore its bacteriostatic rate.Results:The results showed that PDT had a bacteriostatic and bactericidal effect on E.faecalis in the root canal preparation group of 0.04 taper,the bacteriostatic effect of30# root canal group was significantly better than that of 25# and 20# root canal groups;in the root canal preparation group of 25# root canal,the bacteriostatic effect of 0.06 taper was better than that of 0.04 and 0.08 taper groups.Conclusions:PDT has a good effect on E.faecalis.After the root canals were prepared to different degrees and disinfected with photodynamic therapy,the relatively good root canal preparation degrees were 04/30 # root canals and 06/25 # root canals.