The main objective of this study is to evaluate the antibacterial effect of antibacterial photodynamic therapy (aPDT) on Streptococcus mutans (S. mutans) biofilm model in vitro. The selection of photosensitizers is the key step for the efficacy of photodynamic therapy (PDT). However, no studies have been conducted in the oral field to compare the functional characteristics and application effects of PDT mediated by various photosensitizers. In this research, the antibacterial effect of Methylene blue (MB)/650[Formula: see text]nm laser and Hematoporphyrin monomethyl ether (HMME)/532[Formula: see text]nm laser on S. mutans biofilm was compared under different energy densities to provide experimental reference for the clinical application of the two PDT. The yield of lactic acid was analyzed by Colony forming unit (CFU) and spectrophotometry, and the complete biofilm activity was measured by Confocal Laser Scanning Microscopy (CLSM) to evaluate the bactericidal effect on each group. Based on the results of CFU, the bacterial colonies formed by 30.4[Formula: see text]J/cm2 532[Formula: see text]nm MB-aPDT group and 30.4[Formula: see text]J/cm2 532[Formula: see text]nm HMME-aPDT group were significantly less than those in other groups, and the bacterial colonies in HMME-aPDT group were less than those in HMME-aPDT group. Lactic acid production in all treatment groups except the photosensitizer group was statistically lower than that in the normal saline control group. The activity of bacterial plaque biofilm was significantly decreased in the two groups treated with 30.4[Formula: see text]J/cm2 aPDT. Therefore, aPDT suitable for energy measurement can kill S. mutans plaque biofilm, and MB-aPDT is better than HMME-aPDT.

中文翻译：

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体外抗菌光动力疗法对变形链球菌菌斑生物膜的影响

本研究的主要目的是评估抗菌光动力疗法（aPDT）对体外变形链球菌（S. mutans）生物膜模型的抗菌作用。光敏剂的选择是光动力疗法（PDT）疗效的关键步骤。然而，在口腔领域还没有研究比较各种光敏剂介导的PDT的功能特性和应用效果。本研究比较了亚甲蓝（MB）/650[公式：见文]nm激光和血卟啉单甲醚（HMME）/532[公式：见文]nm激光在不同能量下对变形链球菌生物膜的抗菌作用。密度为两种PDT的临床应用提供实验参考。通过菌落形成单位（CFU）和分光光度法分析乳酸的产量，并通过共聚焦激光扫描显微镜（CLSM）测量完整的生物膜活性，以评估对各组的杀菌效果。根据CFU结果，菌落形成30.4[公式：见正文]J/cm2532[公式：见正文]nm MB-aPDT组和30.4[公式：见正文]J/cm2532[公式：见正文]nm HMME-aPDT组明显少于其他组，HMME-aPDT组菌落数少于HMME-aPDT组。除光敏剂组外，所有治疗组的乳酸产量均低于生理盐水对照组。30.4[公式：见正文]J/cm处理的两组菌斑生物膜活性显着降低2aPDT。因此，适用于能量测量的aPDT可以杀死变形链球菌菌斑生物膜，MB-aPDT优于HMME-aPDT。