Nd：YAG激光对天然牙根管内大肠杆菌杀菌效果的体外实验

In vitro experiment of antibacterial effect of Nd: YAG laser on Escherichia coli within tooth root canals

摘要:

目的  建立大肠杆菌离体天然牙根管感染模型，评价脉冲Nd：YAG激光对感染根管内大肠杆菌的杀菌效果。方法  将感染3周的30颗离体前牙随机分为5组，每组6颗牙齿。A组1.5 W激光照射1次，作用30 s；B组2.1 W激光照射1次，作用30 s；C组2.1 W激光重复照射3次，每次30 s，间隔15 s；D组2.5%次氯酸钠NaOCl冲洗后2.1 W激光重复照射3次，每次30 s；对照组单纯用2.5%NaOCl冲洗。每组标本在照射、冲洗前后根管内即刻取样行细菌培养，48 h后计数菌落数（CFU/ml），比较根管内大肠杆菌的杀灭效果。结果  Nd：YAG激光和2.5% NaOCl照射、冲洗后根管内细菌量均显著下降。各组根管内细菌减少量比较差异有统计学意义。A组与B组比较差异无统计学意义（P >0.05），分别与C组、D组、对照组比较差异有统计学意义（P <0.05）；C组与D组比较差异有统计学意义（P <0.05），与对照组比较差异无统计学意义（P >0.05）；D组与对照组比较差异有统计学意义（P <0.05）。结论  Nd：YAG激光和2.5% NaOCl对根管内大肠杆菌具有杀菌作用，两者联合使用杀菌作用更强。

Abstract:

Objective To evaluate the antibacterial effectiveness of Nd: YAG laser for Escherichia coli in infectious tooth root canals in vitro. Methods Thirty anterior teeth inoculated with Escherichia coli for 3 weeks were randomly divided into 5 groups with 6 teeth in each group. In the experiment group A 1.5 W laser dose was applied to root canals for 30 s. In the group B 2.1 W laser dose was applied for 30 s. In the group C 2.1 W laser dose applied for 3 times, 30 s for each irradiation time with an interval of 15 s. In the group D after the teeth were washed by 2.5% sodium hypochlorite, 2.1 W laser was applied for 3 times, 30 s each time. In the control group E the teeth were only washed by 2.5% sodium hypochlorite. Microbiological samples were collected from root canals for bacterial culture immediately before and after irradiation or irrigation, and the colony-forming units (CFU) were counted after 48 h to compare the effect of killing Escherichia coli in root canals. Results The bacteria in root canals significantly decreased after irradiation and/or irrigation, the differences were significant in each group. Pairwise comparison of the reduction of bacteria in root canals of each group was used. There was no statistical difference between the groups A and B (P > 0.05), but both group A and group B had significant differences from the groups C, D and E respectively (P < 0.05). The group C had significant difference from the group D (P < 0.05), but had no significant difference from the control group (P > 0.05). The group D had significant difference from the control group (P < 0.05). Conclusions Both Nd: YAG laser and 2.5% sodium hypochlorite have antibacterial effects on Escherichia coli within root canals, and their combination is more effective.