Pourhajibagher Maryam, Miri-Moosavi Reyhaneh Sadat, Chiniforush Nasim, Safaraei Yashar, Arian-Kia Sasan, Lalegani Mohammad Reza, Bazarjani Farzaneh, Bahador Abbas
Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
Department of Cellular and Molecular Biology, Islamic Azad University East Tehran, Tehran, Iran.
Photodiagnosis Photodyn Ther. 2020 Sep;31:101853. doi: 10.1016/j.pdpdt.2020.101853. Epub 2020 Jun 1.
This study aimed to evaluate the effects of light-activated disinfection (LAD) as a strategy for optimizing root canal disinfection using Chlorella (Chlo) as a natural photosensitizer against Enterococcus faecalis biofilms ex vivo.
The physical and chemical stability and absorption spectra of Chlo were determined. The mature microbial biofilm of E. faecalis was formed in root canals of 70 freshly extracted single-rooted premolars. After determining the minimum inhibitory concentration (MIC) of Chlo using the agar dilution testing, E. faecalis biofilms were exposed in the following groups (n = 10): 1- Chlo at a concentration of 2× MIC, 1- Chlo at a concentration of 4× MIC, 3- Diode laser, 4-2× MIC dose of Chlo-mediated LAD, 5-4× MIC dose of Chlo-mediated LAD, 6-0.2 % chlorohexidine (CHX), and 7- control group (E. faecalis biofilms without exposure to any photosensitizer and light source). The quantitative and qualitative evaluations of E. faecalis biofilms were done using counts of colony forming units (CFUs) and scanning electron microscope (SEM) and fluorescence microscope analysis, respectively.
According to the results, the MIC of Chlo was 125 μg/mL, which inhibited the growth of E. faecalis. To evaluate the anti-biofilm effects of Chlo, the 2× and 4× MICs of Chlo (250 and 500 μg/mL, respectively) were used in the current study. The 4× MIC dose (500 μg/mL) of Chlo-mediated LAD was significantly more effective compared to other groups (P < 0.05), while the lowest percentage of dead cells was detected in the diode laser irradiation group. In addition, there was no significant difference in the log CFU of E. faecalis between the biofilm treated with 500 μg/mL Chlo-mediated LAD (1.27 ± 0.05) versus 0.2 % CHX (1.10 ± 0.06) (P < 0.05). As Moreover, SEM and fluorescence microscope images of the microbial biofilms showed that the highest percentage of dead bacteria was found in the 500 μg/mL Chlo-mediated LAD group.
The results of this study suggest that Chlo-mediated LAD can be used as an adjuvant therapy to eliminate the E. faecalis biofilms in the root canal system.
本研究旨在评估光激活消毒（LAD）作为一种优化根管消毒策略的效果，该策略使用小球藻（Chlo）作为天然光敏剂，在体外对抗粪肠球菌生物膜。
测定了小球藻的物理和化学稳定性及吸收光谱。在70颗新鲜拔除的单根前磨牙的根管中形成粪肠球菌的成熟微生物生物膜。使用琼脂稀释试验确定小球藻的最低抑菌浓度（MIC）后，将粪肠球菌生物膜暴露于以下组（n = 10）：1 - 浓度为2×MIC的小球藻，1 - 浓度为4×MIC的小球藻，3 - 二极管激光，4 - 2×MIC剂量的小球藻介导的LAD，5 - 4×MIC剂量的小球藻介导的LAD，6 - 0.2%氯己定（CHX）以及7 - 对照组（未暴露于任何光敏剂和光源的粪肠球菌生物膜）。分别使用菌落形成单位（CFU）计数、扫描电子显微镜（SEM）以及荧光显微镜分析对粪肠球菌生物膜进行定量和定性评估。
根据结果，小球藻的MIC为125μg/mL，可抑制粪肠球菌的生长。为评估小球藻的抗生物膜效果，本研究使用了2×和4×MIC的小球藻（分别为250和500μg/mL）。与其他组相比，4×MIC剂量（500μg/mL）的小球藻介导的LAD效果显著更优（P < 0.05），而在二极管激光照射组中检测到的死细胞百分比最低。此外，用500μg/mL小球藻介导的LAD处理的生物膜与0.2% CHX处理的生物膜之间，粪肠球菌的CFU对数无显著差异（1.27±0.05对1.10±0.06）（P < 0.05）。此外，微生物生物膜的SEM和荧光显微镜图像显示，在500μg/mL小球藻介导的LAD组中发现的死细菌百分比最高。
本研究结果表明，小球藻介导的LAD可作为辅助治疗手段，用于消除根管系统中的粪肠球菌生物膜。
