Streptococcus mutans (S. mutans) has been implicated as the primary cariogenic species of dental caries in humans. The purpose of this study was to explore the inhibition effects of plasma activated water (PAW) on S. mutans biofilm and the mechanisms. S. mutans biofilm model was established on bovine enamel discs in vitro. Both 12 h old and 48 h old biofilm were constructed. The samples were placed into sterile distilled water and treated with cold plasma or air for 10 min. 0.12% chlorhexidine (CHX) and phosphate buffer saline (PBS) were used as positive and negative control respectively. PAW was confirmed to have strong inactivation effect on S. mutans biofilms. The number of CFU was significantly reduced below the detection limit in both 12 h and 48 h PAW groups, and CLSM images were consistent with CFU results. SEM images showed cells in disorder and burst open with the appearance of melted clusters after PAW treatment. The ORP value of PAW increased obviously with time, while the pH value decreased obviously. The OES analysis indicated that the atomic oxygen (O) emissions at 777 nm and 844 nm and OH emissions at 306–309 nm were detected. Amounts of H₂O₂, NO₂⁻ and NO₃⁻ were detected, which might be major excited reactive species in PAW.

变形链球菌( S. mutans ) 已被认为是人类龋齿的主要致龋物种。本研究旨在探讨血浆活化水（PAW）对变形链球菌生物膜的抑制作用及其机制。体外建立了牛牙釉质盘上的变形链球菌生物膜模型。构建了 12 小时和 48 小时的生物膜。将样品放入无菌蒸馏水中，用冷等离子体或空气处理 10 分钟。0.12% 洗必泰 (CHX) 和磷酸盐缓冲盐水 (PBS) 分别用作阳性和阴性对照。PAW被证实对变形链球菌有很强的灭活作用生物膜。12 h 和 48 h PAW 组的 CFU 数量均显着降低至检测限以下，并且 CLSM 图像与 CFU 结果一致。SEM 图像显示细胞无序并在 PAW 处理后爆裂并出现熔化的簇。PAW的ORP值随时间明显升高，而pH值明显降低。OES 分析表明，在 777 nm 和 844 nm 处的原子氧 (O) 发射和 306-309 nm 处的 OH 发射被检测到。检测到大量的 H ₂ O ₂、NO ₂ ^-和 NO ₃ ^-，这可能是 PAW 中主要的激发活性物质。