This study aimed to use multiple methodologies, including a novel usage of scanning electron microscopy (SEM), to evaluate the antimicrobial actions of sodium hypochlorite (NaOCl) admixed with clodronate or etidronate in root canal irrigation. The study also examined the usefulness of colony counting as a biofilm assessment methodology. Seven day Enterococcus faecalis biofilms were grown on hydroxyapatite discs. The discs were disinfected with 0.26 M clodronate-5% NaOCl, 0.26 M etidronate-5% NaOCl, 5% NaOCl, or treated with phosphate buffered saline (PBS). Assessments were performed using colony counting, SEM and the XTT reduction assay. The XTT assessment used the same groups but with 2.5% NaOCl. For colony counting, bacteria were removed from the discs by vortex mixing, followed by plating. The discs were subsequently fixed for SEM imagining and evaluators scored the SEM micrographs for remaining bacteria. Antibiofilm actions were assessed with the Kruskal-Wallis and Dunn's multiple comparison tests. SEM micrographs and the XTT assay revealed no differences between the NaOCl controls and the clodronate or etidronate mixtures with NaOCl (P > 0.05). It was concluded that the chelator mixtures with NaOCl had antibiofilm actions comparable to NaOCl. Furthermore, vortex mixing incompletely removed biofilm from HA discs in the PBS controls and hence colony counting using E. faecalis biofilms on hydroxyapatite discs could not be used for intergroup comparisons involving PBS. Additionally, colony counting could not be used for comparisons between the NaOCl treatment groups because the removal of bacteria from the substrate by vortex mixing was affected by the irrigant type.

本研究旨在使用多种方法，包括扫描电子显微镜 (SEM) 的新用途，来评估次氯酸钠 (NaOCl) 与氯膦酸盐或依替膦酸盐混合在根管冲洗中的抗菌作用。该研究还检查了菌落计数作为生物膜评估方法的有效性。7天粪肠球菌生物膜生长在羟基磷灰石盘上。椎间盘用 0.26 M 氯膦酸盐-5% NaOCl、0.26 M 依替膦酸盐-5% NaOCl、5% NaOCl 消毒，或用磷酸盐缓冲盐水 (PBS) 处理。使用菌落计数、SEM 和 XTT 还原测定进行评估。XTT 评估使用相同的组，但使用 2.5% 的 NaOCl。对于菌落计数，通过涡旋混合从圆盘上去除细菌，然后进行平板接种。随后将圆盘固定用于 SEM 成像，评估人员对剩余细菌的 SEM 显微照片进行评分。使用 Kruskal-Wallis 和 Dunn 的多重比较测试评估了抗生物膜作用。SEM 显微照片和 XTT 测定显示 NaOCl 对照与氯膦酸盐或依替膦酸盐与 NaOCl 的混合物之间没有差异（P > 0.05）。结论是螯合剂与 NaOCl 的混合物具有与 NaOCl 相当的抗生物膜作用。此外，涡旋混合未完全去除 PBS 对照中 HA 圆盘的生物膜，因此在羟基磷灰石圆​​盘上使用粪肠球菌生物膜进行菌落计数不能用于涉及 PBS 的组间比较。此外，菌落计数不能用于 NaOCl 处理组之间的比较，因为通过涡旋混合从基质中去除细菌会受到冲洗剂类型的影响。