目的:体外观察不同光敏剂浓度和不同激光能量密度的TBO-PDT抑制离体牙根管内粪肠球菌的效果, 确定最佳光敏剂参数和激光参数, 并在此基础上探讨TBO-PDT在抑制离体牙根管内粪肠球菌上的作用优势, 为PDT应用于根管消毒的临床实践提供理论与实验依据。方法:对离体牙进行根管预备, 接种粪肠球菌, 厌氧培养21 d后建立粪肠球菌感染根管模型。将其随机分组:A组为阴性对照组, 以生理盐水冲洗根管;B组为阳性对照组, 以5.25%NaClO冲洗根管;其余组别根据光敏剂浓度的不同, 分为C1组80 μg/mL、D1组90 μg/mL、E1组100 μg/mL、F1组110 μg/mL、G1组120 μg/mL, 避光孵育5 min后用波长为630 nm功率密度为90 mW/cm2半导体激光在根管内上下提拉螺旋照射90 s;根据光照时间的不同, 分为C2组30 s、D2组60 s、E2组90 s、F2组120 s、G2组150 s, 光敏剂浓度为100 μg/mL避光孵育5 min后,用波长为630 nm功率密度为90 mW半导体激光在根管内上下提拉螺旋照射各实验组牙标本, 实验处理前后即刻取样, 厌氧培养24 h, 计数平板菌落, 明确实验处理前后根管内粪肠球菌的数量变化。结果:(1)不同光敏剂浓度下TBO-PDT对根管内粪肠球菌抑菌效果的影响。平板菌落计数结果显示:不同光敏剂浓度的各组抑菌率随光敏剂浓度的增加而增高。与阴性对照组相比, C1组、D1组、E1组、F1组和G1组的抑菌率显著提高, 而F1组和G1组两组间抑菌率没有明显差异。(2)不同光照时间对TBO-PDT抑制实验根管内以生物膜形式存在的粪肠球菌的抑菌效果。平板菌落计数结果显示:不同光照时间的各组抑菌率随光照时间延长而增高。与阴性对照组相比, 其中C2组、D2组、E2组、F2组和G2组的抑菌率明显升高, 而F2组和G2组两组间抑菌率没有明显差异。结论:TBO-PDT对以生物膜形式存在的粪肠球菌有明显的抑制作用, 实验证实TBO-PDT最佳光敏剂浓度为110 μg/mL, 最佳光照时间为120 s。

Objectives:The purpose of this study was to assess the antibacterial effect of TBO-photodynamic therapy on Enterococcus faecalis which infected extracted root canals and to determine the optimum photosensitizer concentration and light dose parameters. On that basis, it was designed to study the advantage of TBO-PDT on the antibacterial effects. This study provides theoretical and experimental evidence for PDT applied to clinical practice root canal disinfection. Methods:We made root canal preparation for experimental teeth. After preparation, the specimens were infected with Enterococcus faecalis for 21 d to establish a model of Enterococcus faecalis root canal infection. The specimens were randomly divided into twelve groups. Group A was irrigated with physiological saline. Group B was irrigated with 5.25%NaClO. For other groups, they were divided into five groups according to different concentrations of photosensitizer, as Group C1 80μg/ml、Group D1 90 μg/mL、Group E1 100 μg/mL、Group F1 110μg/ml、Group G1 120 μg/mL. The specimens were incubated for 5 minutes in the dark, and then exposured to light at 630nm 90mW for 90s in a spiral pattern. According to the irradiation time, the other specimens were divided into five groups, as Group C2 30 s, Group D2 60 s, Group E2 90 s, Group F2 120 s, and Group G2 150 s. The specimens were incubated for 5 minutes in the dark with a 100 μg/mL concentration of photosensitizer, and then exposured to light at 630 nm 90 mW for certain time in a spiral pattern. Take Samples immediately before and after the experimental treatment. Anaerobic culture them for 24 h and count the colonies in the plates to clear the changes in the number of Enterococcus faecalis in experimental root canals after treatment. Results:(1) The antibacterial effects of TBO-PDT in different photosensitizer concentration groups. Plate colony count results showed that:Different photosensitizer concentration groups antibacterial rates were increased when the concentration of the photosensitizer was increased. Compared with the negative control group, the antibacterial rates of Group C1 , D1, E1, F1 and G1 were significantly increased. However, the antibacterial rates between Group F1 and G1 were not significantly different.(2) The antibacterial effects of TBO-PDT in different illumination time groups. Plate colony count results showed that:Different photosensitizer concentration groups antibacterial rates were increased with the illumination time extension. Compared with the negative control group, the antibacterial rates of Group C2 , D2, E2, F2 and G2 were significantly increased. However, the antibacterial rates between Group F2 and G2 were not significantly different. Conclusion:TBO-PDT significantly inhibited Enterococcus faecalis which exist in the form of biofilm. Our study confirmed the best photosensitizer concentration of TBO-PDT is 110μg/ml, and the optimal illumination time is120s.