摘要目的:探讨光动力疗法（PDT）联合乙二胺四乙酸二钠（EDTA）对根管侧支内粪肠球菌的杀灭效果。方法:选取64颗人单根管离体前磨牙制备人工根管侧支，建立粪肠球菌根管侧支感染模型。将感染模型按随机数字表法分为PDT组、PDT联合EDTA组、阳性对照组和阴性对照组，每组16个。PDT组于根管中注入40 μg/ml血卟啉单甲醚，避光孵育5 min后将激光器的光纤插入根管内上下提拉照射90 s（激光功率为45 mW）；PDT联合EDTA组根管给予5 ml质量分数为17%的EDTA溶液冲洗1 min，无菌纸尖吸出EDTA后进行PDT处理，操作同PDT组；阳性对照组和阴性对照组根管分别给予5 ml质量分数为5.25%的NaClO溶液和质量浓度为9 g/L的NaCl溶液冲洗1 min。各组处理前、后分别用K锉于根管侧支内取样，进行平板菌落计数。处理后将各组牙根置于无菌脑心浸液肉汤（BHI）培养基中厌氧培养24 h，再用K锉取样，统计检出细菌的根管侧支个数。采用扫描电子显微镜观察处理后各组根管侧支内壁的形貌。结果:PDT联合EDTA组的杀菌率达99.56%，明显高于阴性对照组（1.98%）、阳性对照组（85.87%）和PDT组（87.53%），差异均具有统计学意义（均 P<0.05）。回复实验结果显示，PDT联合EDTA组检出细菌的根管侧支数为5个，明显少于阴性对照组（15个）、阳性对照组（12个）和PDT组（11个），差异均具有统计学意义（均 P<0.05）。扫描电子显微镜观察结果显示，PDT联合EDTA组未见明显粪肠球菌在根管侧支内壁附着。 结论:PDT联合EDTA对根管侧支内感染的粪肠球菌杀灭效果良好，有望为临床根管治疗中有效杀灭根管侧支内的粪肠球菌提供一种新方法。

abstractsObjective:To investigate the disinfection effectiveness of photodynamic therapy (PDT) combined with ethylenediaminetetraacetic acid (EDTA) disodium salt solution on enterococcus faecalis in lateral root canals.Methods:Sixty-four human single root canal premolars were selected to prepare artificial root canal collaterals, and E. faecalisin root canal collateral infection models were established. The infection model was divided into PDT group ( n=16), PDT combined with EDTA group ( n=16), positive control group ( n=16) and negative control group ( n=16) according to random number table method. In the PDT group, 40 μg/ml hematoporphyrin monomethyl ether was injected into the root canal, and then the root canal was irradiated with a 45 mW laser for 90 s after 5 min incubation. In the PDT combined with EDTA group, the root canal was given 5 ml EDTA solution with 17% mass fraction for 1 min, and then treated with the method same as the PDT group. In the positive control group, the root canal were given 5 ml NaClO solution with a mass fraction of 5.25 % for 1 min. In the negative control group, the root canal were given NaCl solution with a mass concentration of 9 g/L for 1 min. Before and after the treatments, samples were taken in the lateral branches of the root canal with a K file to count plate colonies. After treatments, the roots of each group were placed in sterile brain heart infusion broth (BHI) medium for anaerobic culture for 24 h, and then sampled with a K file, and the number of root canal collaterals was detected statistically. Scanning electron microscopy was used to observe the morphology of the inner wall of lateral branches of root canals after treatments. Results:The sterilization rate of PDT combined with EDTA group was 99.56%, which was significantly higher than that of negative control group (1.98%), positive control group (85.87%) and PDT group (87.53%), the differences were statistically significant (all P<0.05). The reply experiment shows that the number of infection root canals was only 5, which was less than the negative control group (15), positive control group (12) and PDT group (11), and the differences were statistically significant (all P<0.05). Scanning electron microscopy observations showed that no obvious E. faecalis adhered to the inner wall of root canal of PDT combined with EDTA group. Conclusions:PDT combined with EDTA has a good disinfection effectiveness on E. faecalis in lateral canals, and it is expected to provide a new method for the effective killing of E. faecalis in lateral canals in clinical root canal therapy.