纳米银对牙本质表面粪肠球菌生物膜的杀菌作用

Bactericidal effect of nano-silver against E.faecalis biofilm on dentin

目的研究纳米银对牙本质表面粪肠球菌生物膜的杀菌作用,为探寻新型有效的根管消毒药物提供实验依据。方法制备牙本质片309个,随机分成3组,在牙本质表面形成粪肠球菌生物膜后,分别用0.1%纳米银溶液、1.313%次氯酸钠溶液和0.9%氯化钠溶液处理,3组分别于处理0(即处理前)、1、6、12、24h时取出样本,应用活菌菌落计数法检测粪肠球菌生物膜活菌数,激光共聚焦显微镜研究粪肠球菌生物膜活菌/死菌空间分布。结果随着0.1%纳米银溶液处理时间的延长,粪场球菌生物膜活菌数逐渐降低,至24h生物膜内无活菌。生物膜外层、中间层、内层活菌百分比及其平均厚度也随处理时间延长逐渐减少,0.1%纳米银溶液处理1h生物膜结构未完全解体,但生物膜中间层和内层活菌百分比分别降至(27.4%±5.6%)和(20.8%±4.5%),处理6h分别降至(2.0%±0.9%)和(1.8%±0.9%),处理12和24h,生物膜各层活菌百分比与1.313%次氯酸钠溶液组差异无统计学意义(P>0.05)。结论 0.1%纳米银溶液对粪肠球菌生物膜有较强的渗透能力和杀菌作用,其杀菌作用随处理时间的延长而增强,作用时间以24h以上为佳。

Objective To evaluate the bactericidal effect of nano-silver against E.faecalis biofilm.This provides experimental evidence for seeking a novel effective root canal disinfectant.Methods 309 dentin slices were inoculated with E.faecalis suspension for 24 h to form biofilms on the surfaces of dentin slices.Thereafter,all specimens were randomly divided into 3 groups of 103 each,and treated with 0.1% nano-silver solution,1.313% sodium hypochlorite solution and 0.9% physiological saline,respectively.After treated for 0,1,6,12 and 24 h,specimens of each group were taken to investigate the viable count of E.faecalis biofilms by colony-forming unit（CFU） counts,and to detect the viable/dead bacteria spatial distribution of E.faecalis biofilms by confocal laser scanning microscopy（CLSM）.Biofilm scanned images were analyzed and the viablepercentages of each layer of biofilms were calculated by Fluoview.Results The viable counts of E.faecalis biofilm decreased with the extending of treatment time,and E.faecalis biofilm was eliminated after treated by 0.1% nano-silver for 24 h.CLSM observation showed that the average thicknesses of E.faecalis biofilm and viable cells percentages of the outer,middle and inner layers reduced with the treatment time.After treated by 0.1% nano-silver solution for 1 h,E.faecalis biofilm was not completely destroyed.However,the percentages of viable cells of the middle （27.4%±5.6%） and inner （20.8%±4.5%） layers decreased.These rapidly reduced to （2.0%±0.9%） and （1.8%±0.9%） when treated for 6 h.There were no statistical differences of the percentages of viable cells in each layer between the 0.1% nano-silver solution group and the 1.313% sodium hypochlorite solution group when treated for 12 h and 24 h（P0.05）.Conclusions 0.1% nano silver solution might penetrate E.faecalis biofilm easily and have a strong bactericidal effect against E.faecalis biofilm formed on dentin slices.The bactericidal effect was enhanced with the time of treatment,and the treatment time should be over 24 h for a better effect of root canal disinfection.