Division of Endodontics, Department of Advanced Oral Sciences and Therapeutics, University of Maryland, School of Dentistry, Baltimore, Maryland, USA.
Prince Abdulrahman Advanced Dental Institute, Riyadh, Kingdom of Saudi Arabia.
Int Endod J. 2022 Oct;55(10):1081-1090. doi: 10.1111/iej.13804. Epub 2022 Aug 11.
The lipopolysaccharides-dentine-infection (LPS-dentine-infection) models and sampling techniques frequently used to evaluate LPS disinfection have limitations. In this study, a LPS-dentine-infection model was devised using fluorescent conjugate LPS. Secondly, a sampling technique using cryogenic grinding for intraradicular LPS analysis was evaluated. Thirdly, the effectiveness of the XP-endo Finisher (XP-EF) was compared with passive ultrasonic irrigation (PUI) in removing LPS from root canal system.
Sixty-nine mandibular premolars were submitted to dentine pretreatment and inoculated with fluorescent LPS conjugate (Alexa Fluor® 594). Twenty-three teeth were analysed under confocal laser scanning microscopy (CLSM) to validate this modified LPS-dentine-infection model. Forty-six teeth were randomly divided into two experimental groups: XP-EF (n = 23) and PUI (n = 23). All teeth were instrumented with XP-endo shaper (XPS; FKG Dentaire) and 2.5% NaOCl. The root canals were sampled with paper points before (s1) and after (s2) instrumentation and after supplemental treatment (s3) with XP-EF and PUI. After s3, all roots were cryogenically ground for intraradicular LPS analysis (s4). Limulus amebocyte lysate assay was used for LPS quantification. The Friedman test was used for differences in LPS among four time-points (s1, s2, s3, and s4). Dunn's test was used for pairwise testing of time-points. The significance level was set at 5% (p < .05).
Fluorescent LPS conjugate was detected in 100% of the samples under CLSM with a penetration depth of approximately 400 μm into dentine. Chemo-mechanical preparation using XPS files significantly reduced LPS levels (p < .05). Both the XPS and PUI improved the LPS disinfection (p < .05), with no difference between them (p > .05). LPS was recovered from all samples after cryogenic grinding. The residual amount of LPS detected using the cryogenically sampling technique at s4 was approximately three times greater than with the paper-point sampling technique at s3.
This study established a modified LPS-dentine-infection model using fluorescent conjugate LPS, and validated a LPS sampling technique for using cryopulverization intraradicular LPS analysis. Moreover, both the XP-EF and PUI further improved LPS disinfection from the root canals, and the innovative XP-EF was as effective as PUI.
内毒素-牙本质感染（LPS-牙本质感染）模型和采样技术常用于评估 LPS 消毒效果，但存在局限性。本研究采用荧光结合 LPS 构建 LPS-牙本质感染模型，其次评估了用于根管内 LPS 分析的低温研磨采样技术，最后比较了 XP-endo Finisher（XP-EF）和被动超声冲洗（PUI）对根管系统中 LPS 的清除效果。
69 颗下颌前磨牙进行牙本质预处理并接种荧光 LPS 结合物（Alexa Fluor®594）。23 颗牙齿通过共聚焦激光扫描显微镜（CLSM）进行分析，以验证改良的 LPS-牙本质感染模型。46 颗牙齿随机分为两组：XP-EF（n=23）和 PUI（n=23）。所有牙齿均使用 XP-endo Shaper（XPS；FKG Dentaire）和 2.5%次氯酸钠进行器械预备。在器械预备前（s1）、后（s2）和补充治疗后（s3，XP-EF 和 PUI）用纸尖取样。s3 后，所有根均经低温研磨进行根管内 LPS 分析（s4）。鲎变形细胞溶解物（LAL）试验用于 LPS 定量。采用 Friedman 检验比较四个时间点（s1、s2、s3 和 s4）的 LPS 差异。采用 Dunn 检验进行两两比较。显著水平设为 5%（p<.05）。
CLSM 下 100%的样本均检测到荧光 LPS 结合物，穿透深度约为 400μm。使用 XPS 文件进行化学机械预备可显著降低 LPS 水平（p<.05）。XPS 和 PUI 均可改善 LPS 消毒效果（p<.05），两者之间无差异（p>.05）。低温研磨后所有样本均回收 LPS。s4 时，采用低温采样技术检测到的 LPS 残留量约为 s3 时纸尖采样技术的三倍。
本研究建立了一种改良的荧光 LPS 结合物 LPS-牙本质感染模型，并验证了一种用于低温研磨根管内 LPS 分析的 LPS 采样技术。此外，XP-EF 和 PUI 均进一步提高了根管内 LPS 的消毒效果，新型 XP-EF 与 PUI 效果相当。
