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目的观察光动力疗法(Photodynamic therapy,PDT)对离体牙侧支根管内粪肠球菌的杀灭作用。方法选取人类单根管离体前牙60颗,随机分为3组。常规根管预备后,在牙的近远中面距离根尖孔3 mm处制备15#K锉直径(锉尖直径为150μm)的人工侧支根管,建立粪肠球菌感染模型。实验组为PDT组,以40μg/ml血卟啉单甲醚(Hemato-porphyrin monomethylether,HMME)为光敏剂,避光孵育5 min后用激光功率为80 mW的532 nm半导体激光在根管内上下提拉螺旋照射120 s;阳性对照组为5.25%次氯酸钠冲洗组;阴性对照组为生理盐水冲洗组。各组实验牙标本(每个离体牙近中面侧支根管作为实验前标本,远中面侧支根管作为对应的实验后标本)处理前与处理后即刻用20#K锉取侧支根管内碎屑,然后将碎屑转至含5 ml TPY液体培养基的试管中,10倍递增连续稀释后厌氧培养24 h,菌落计数并推算对应的菌液浓度。结果菌落计数统计结果显示:(1)与阴性对照组(生理盐水冲洗组)比较,HMME-PDT处理组和阳性对照组(5.25%次氯酸钠冲洗组)各侧支根管内细菌量均显著下降(P<0.01);(2)HMME-PDT对侧支根管内粪肠球菌的杀灭效果(92.56%)显著优于阳性对照组(76.93%),差异有显著意义(P<0.01)。结论 HMME-PDT对侧支根管内粪肠球菌有很好的杀灭作用,将为根管消毒提供一种新的有效途径。
Objective To observe the killing effect of Photodynamic therapy (PDT) on Enterococcus faecalis isolated from the root canal branch of the lateral branch. Methods 60 single isolated human anterior teeth were randomly divided into three groups. Conventional root canal preparation, the preparation of 15 # K file diameter (file tip diameter of 150μm) artificial lateral root canal at a distance of 3 mm near and far from the apical foramen of the tooth to establish Enterococcus faecalis infection model. The experimental group was PDT group. Hemato-porphyrin monomethylether (HMME) was used as photosensitizer and incubated for 5 min in the dark. The PDT group was irradiated with a 532 nm laser with a laser power of 80 mW, Thyrotropin irradiation for 120 s; positive control group was 5.25% sodium hypochlorite flushing group; negative control group was saline flushing group. Each group of experimental dental specimens (each isolated tooth near the median lateral branch canal as the pre-test specimens, distal mid-lateral root canal as the corresponding experimental specimens) before and immediately after treatment with 20 # K filing side The root canal detritus, and then the debris transferred to 5 ml TPY liquid medium tube, 10-fold serial dilution of anaerobic culture 24 h, colony count and calculate the corresponding bacterial concentration. Results The results of colony counting showed that: (1) Compared with the negative control group (saline flush group), the bacterial counts in the lateral branch root canal of HMME-PDT group and positive control group (5.25% sodium hypochlorite flushing group) P <0.01). (2) The killing effect of HMME-PDT against Enterococcus faecalis in the lateral branch canal (92.56%) was significantly better than that of the positive control group (76.93%), the difference was significant (P <0.01). Conclusion HMME-PDT has a good killing effect on Enterococcus faecalis in the lateral branch canal, which will provide a new effective way for root canal disinfection.