Er:YAG激光在不同根尖工作宽度时对根管内粪肠球菌杀灭效果的研究

Bactericidal effect of Er: YAG laser with different apical working width on Enterococcus faecalisin experimentally infected root canals

目的：观察Er：YAG激光在不同照射时间及不同根尖工作宽度时的杀菌效果。方法：取粪肠球菌感染根管模型125个,随机取10个样本用于检测根管壁细菌基线数。115个样本随机分为5组,1机械预备＋Er：YAG激光＋次氯酸钠（Na Cl O）组（n=40）：根据根管预备型号再分为#20、#25、#30、#40 4个亚组（n=10）,均用Er：YAG激光加52.5 g/L Na Cl O处理1 min;2机械预备＋Na Cl O组（n=10）：将根管预备至#40后,用52.5 g/L Na Cl O处理1 min;3Er：YAG激光＋Na Cl O处理组（n=39）：按激光处理时间分为E0（30 s）、E1（1 min）、E2（2 min）3个亚组后（n=13）,向根管内注满52.5 g/L Na Cl O,并用Er：YAG激光照射相应时间;4阳性对照组（n=13）：用3 m L 52.5 g/L Na Cl O处理根管1 min;5阴性对照组（n=13）：用3 m L生理盐水处理根管1 min。处理结束后,分别采集各组根管壁表面和不同深度的牙本质碎屑进行细菌培养计数。结果：1Er：YAG激光＋52.5 g/L Na Cl O组在根管壁各深度处的细菌减少率均显著高于阴、阳性对照组（P〈0.05）;E0、E1、E2组在根管壁表面和0~100μm深度处的细菌减少率基本相似（P〉0.05）,而在100~200μm和200~300μm处,E0组细菌减少率明显低于E1、E2组（P〈0.05）,E1和E2相比P〉0.05。2#30/Er：YAG/Na Cl O组牙本质深层细菌减少率可达99%以上。#20/Er：YAG/Na Cl O组与#40/Na Cl O组比较P〉0.05。结论：Er：YAG激光可增强Na Cl O的杀菌作用,在减少根尖预备工作宽度的同时可达到同样的杀菌效果。

AIM： To investigate the bactericidal effect of Er： YAG laser with different irradiation time and apical working width on enterococcus faecalis in root canals. METHODS： Root canals of 125 human teeth with single straight canals were inoculated with Enterococcus faecalis for 4 weeks,10 teeth were randomly selected for bacteria baseline data at different depths. The remaining 115 teeth were randomly divided into 5 groups and treated as follows：1 mechanical instrumentation ＋ Er： YAG laser ＋ 52. 5 g /L Na Cl O; 2 mechanical instrumentation ＋ 52. 5 g /L NaCl O; 3 Er： YAG laser ＋ 52. 5 g / L Na Cl O（ E0： 30 s,E1： for 1 m,E2： 2 m）; 4 52. 5 g / L Na Cl O treatment for 3 m（ and 5 normal saline for 1 m）. After treatment,the numbers of bacteria on the surface of root canal wall at the depth of 0- 100,100- 200 and 200- 300 μm were counted and the bacterial reduction were analyzed by one- way ANOVA.RESULTS： The bactericidal efficiencies of Er： YAG plus Na Cl O were higher than that of 52. 5 g / L Na Cl O and normal saline（ P 〈 0. 05）. On the surface and at 0- 100 μm depth,the bacterial reduction of different duration of Er： YAG laser treatment were similar（ P 〉 0. 05）. But at depth of 100- 200 μm and 200- 300 μm,the bactericidal efficiency of group E0 was lower than that of groups E1 and E2（ P 〈 0. 05）,E1 vs E2（ P 〉 0. 05）. Treatment with Er： YAG laser after enlarging the root canals to #30 /0. 04 showed more than 99% reduction of bacteria in the deep layers（ 100- 200 μm and 200- 300 μm） of the dentinal tubules. Group #20 /0. 04 vs group #40 /0. 04（ P 〉 0. 05）.CONCLUSION： Er： YAG laser can enhance the bactericidal effect of sodium hypochlorite. Furthermore,Er： YAG laser can reduce the width of canal preparation while achieve the same sterilizing effect.