苯扎氯铵对粪肠球菌感染根管的体外抑菌研究

In vitro evaluation of the antibacterial potential of benzalkonium chloride in root canals infected by Enterococcus faecalis

目的评价苯扎氯铵作为根管冲洗液对离体牙感染根管内粪肠球菌(E.faecalis)的抑菌效果。方法 64颗因正畸减数拔除的健康前磨牙,高压灭菌后接种E.faecalis建立感染模型,接种前、后分别采用抽签法随机取出2颗作前后对照,组织学Brown&Brenn染色和扫描电镜(SEM)观察E.faecalis在根管内的感染状态。其余按不同冲洗药物随机分为6组(每组10例):0.05%苯扎氯铵溶液组、0.1%苯扎氯铵溶液组、3%过氧化氢溶液组、2.5%次氯酸钠溶液组、5.25%次氯酸钠溶液组、0.9%氯化钠溶液组。冲洗前、后分别取样作细菌学培养,计数菌落形成单位。采用t检验分析各组冲洗前后根管内细菌量差异,ANOVA法分析各组间细菌减少量的差异,比较苯扎氯铵与过氧化氢和次氯酸钠溶液对E.faecalis的抑菌效果,并用SEM观察各组冲洗后根管表面细菌感染情况。结果 (1)组织学结果显示:E.faecalis感染根管样本的牙本质小管内见蓝色深染的细菌颗粒,深度达250~1050μm;接种前样本中,根管视野干净,未见蓝色深染的细菌颗粒。SEM观察在感染根管样本中,E.faecalis成团、成串附着于根管壁,形成生物膜结构;接种前样本中,根管壁表面干净,牙本质小管和管间牙本质结构清晰可见。(2)细菌学培养结果显示:除0.9%氯化钠溶液组外,其余5组根管内E.faecalis均下降(P<0.05)。0.05%和0.1%苯扎氯铵溶液冲洗前后的细菌减少量(7.90±2.18、8.30±2.21)大于3%过氧化氢溶液(5.30±2.31)和2.5%次氯酸钠溶液(6.10±1.20)组(P<0.05),但与5.25%次氯酸钠溶液(8.70±1.89)差异无统计学意义(P>0.05);0.05%和0.1%苯扎氯铵溶液组冲洗前后细菌减少量差异无统计学意义(P>0.05)。SEM观察苯扎氯铵、5.25%次氯酸钠溶液冲洗后根管表面较3%过氧化氢溶液、2.5%次氯酸钠溶液冲洗后洁净。结论苯扎氯铵对离体牙根管内E.faecalis有较强的抑菌效果。

 Objective To evaluate the antibacterial potential of benzalkonium chloride in root canals infected by Enterococcus faecalis（E.faecalis）. Methods Sixty-four human premolars extracted for orthodontics were prepared and inoculated with E.faecalis. Two teeth were selected respectively using random lottery method before and after inoculation,then split in to two halves along the mesiodistal axis. One half was processed with light microscopic（Brown ＆ Brenn stain）to check the bacteria in dentinal tubules,and the other was observed with SEM to investigate the bacterial status in infected root canals. The rest of the teeth were randomly assigned to the following groups：0.05% benzalkonium chloride,0.1%benzalkonium chloride,3% hydrogen peroxide,2.5% sodium hypochlorite,5.25% sodium hypochlorite, 0.9% sodium chloride for endodontic irrigation. Before and after irrigating,microbiological samples were collected from root canals for bacteriological culture,and colony forming units（CFU）were counted. The t-test was used to analyze the difference of bacterial counts in root canals before and after irrigation. The difference of bacterial descent among the six groups were analyzed by ANOVA. Bacterial status after irrigation was assessed with SEM. Results （1）E.faecalis was found to penetrate into the dentinal tubules about 250 ~ 1050 μm. In the infected root canal samples,E.faecalis was attached to the root canal wall to form a biofilm structure.（2）The number of E.faecalis in root canal in each group was effectively reduced excepted 0.9% sodium chloride group （P〈0.05）. The bacterial descent of 0.05% ,0.1%benzalkonium chloride groups（7.90 ± 2.18,8.30 ± 2.21）was significantly more than that of 3% hydrogen peroxide group（5.30 ± 2.31）and 2.5% sodium hypochlorite group（6.10 ± 1.20,P〈0.05）. There were no statistical difference among 0.05% benzalkonium chloride group,0.1% benzalkonium chloride group and 5.25% sodium hypochlorite group（8.70±1.89,P〉0.05）. Root canal surfaces were cleaner in benzalkonium chloride and 5.25% sodium hypochlorite groups than 3% hydrogen peroxide group and 2.5% sodium hypochloritethe group with SEM observation. Conclusion It was suggested that benzalkonium chloride solution had potential antibacterial activity against E.faecalis when it was used for root canal irrigation.