| Objectives:Chronic apical periodontitis is mainly caused by inflammatory reactions caused by bacteria and their metabolites in the root canal reaching the periapical tissues.Among them,gram-negative(G-)anaerobic bacteria are the dominant bacteria in infected root canals and periapical lesions.Endotoxin is the cell wall lipopolysaccharide of G-bacteria;it is the main virulence factor.Endotoxin released by bacteria present in the infected root canal for a long period can directly poison cells;stimulate immune cells;promote the secretion of various inflammatory mediators,such as IL-1? and TNF-?;induce inflammation.Laser is a new mode of treatment.In this study,changes in bacteria,endotoxin and IL-1? in root canals before and after application of an Nd:YAP laser were observed.Methods:This study is mainly divided into three parts of experiments.Part one: Tne change of bacteria in the root canal before and after Nd:YAP laser treatment.The selected subjects presented 10 cases of single-root-canal infected teeth clinically diagnosed with chronic periapical periodontitis,which were randomly divided into two groups with 5 cases in each group.All patients underwent opening the pulp cavity and root canal preparation.In the experimental group,a 1341 nm Nd:YAP laser(1.8w,5Hz,360 m J)was used to irradiate the root canal.Select 220 um fiber and the length of the fiber entering the root canal is 2mm less than the working length.The fiber is lifted up and down along the long axis of the root canal for 10 s.The experimental and control groups were sampled with sterile paper points and stored in PBS before root canal preparation and immediately after laser treatment.The number of bacteria was determined by colony counts.Part two: The change of endotoxin content in the root canal before and after Nd:YAP laser treatment.Experiment object selection and processing were the same as part one.The groups were sampled with sterile paper points and stored in pyrogen free water before root canal preparation and immediately after laser treatment.The endotoxin content was determined by a limulus amoebocyte lysate test.Part three: The change of IL-1? content in the root canal before and after Nd:YAP laser treatment.Experiment object selection and processing were the same as part one.The groups were sampled and stored in sample dilution solution before root canal preparation and half an hour after laser treatment.The level of IL-1? was determined by ELISA.Result:1.The number of bacteria in the root canal of the experimental group and the control group were 5.455±0.152log10 CFU/ml,5.474±0.147log10 CFU/ml respectively before treatment,there was no statistical difference(P>0.05).After treatment,the number of bacteria in the root canal in the experimental group was3.616±0.150log10 CFU/ml,and in the control group was 4.371±0.230log10 CFU/ml.The experimental group decreased more than the control group,and there was statistical difference(P<0.05).2.There was no significant difference in endotoxin content between the experimental group and the control group before treatment(P>0.05),which were 22.92±2.22EU/ml and 22.73±2.81EU/ml respectively.After treatment,the experimental group decreased to 2.69±0.74EU/ml,and the control group decreased to 10.16±2.27EU/ml.The experimental group showed more reduction than the control group,and the difference was statistically significant(P<0.05).3.The levels of IL-1? in the root canal of the experimental group and the control group were 18.84±1.94ng/L and 20.10±0.79ng/L respectively before treatment,and there was no significant difference(P>0.05).After treatment,the IL-1?contents of the two groups were both decreased,being 8.16±1.66ng/L and15.87±2.11ng/L respectively,and the reduction in the experimental group was more obvious(P<0.05).Conclusions:Nd:YAP laser with a wavelength of 1341 nm was used to irradiate infected root canals for 10 s with an average power of 1.8 W and a pulse energy of 360 m J,which significantly reduced the number of bacteria and endotoxin content in the root canals,reduced the expression level of IL-1? in the infected root canals. |
PDF Full Text Request