Clinic of Preventive Dentistry, Periodontology and Cariology, Center of Dental Medicine, University of Zürich, Zürich, Switzerland.
Int Endod J. 2015 May;48(5):435-40. doi: 10.1111/iej.12332. Epub 2014 Jul 28.
To monitor chlorine consumption from nonagitated aqueous sodium hypochlorite (NaOCl) solutions in human root canals using a recently developed assay, which can determine the order of magnitude of available chlorine in small volumes of liquid.
The root canals of 80 extracted single-rooted human teeth were instrumented to ProTaper Universal F4 and irrigated using 1% NaOCl. Subsequently, canals were irrigated with copious amounts of deionized water to rinse out the residual chlorine. Subsequently, the teeth were sealed externally and placed in a water bath of 37 °C. Root canals were filled with NaOCl of 1%, 2.75%, 5.5%, or distilled water for 1, 10, 100 or 1000 min (n = 5 teeth per solution and time). Consumption of chlorine was measured using paper points pre-impregnated with 15% potassium iodide. Colour change of the paper points was determined photo-electronically, assessing their red value after absorbing solutions from root canals. Measurements were compared to a standard series of NaOCl down to 0.001% (n = 5 paper points per concentration).
Red values of the paper points inserted into the root canal were affected by initial NaOCl concentration and time (two-way anova, P < 0.05). If NaOCl concentrations above 0.1% are considered to be clinically relevant, then 5.5% NaOCl retained its activity in the root canal for more than 100 min, whereas 1% NaOCl lost its activity between 10 and 100 min.
Nonagitated NaOCl solutions can remain biologically active in human root canals for extended time periods.
使用最近开发的一种测定法来监测非搅拌的水溶液次氯酸钠（NaOCl）在人根管中的氯消耗，该方法可测定小体积液体中有效氯的数量级。
将 80 颗已提取的单根人牙的根管用 ProTaper Universal F4 锉进行预备，并使用 1%的 NaOCl 冲洗。随后，用大量去离子水冲洗根管以冲洗掉残留的氯。随后，将牙齿外部密封并置于 37°C 的水浴中。将根管分别填充浓度为 1%、2.75%、5.5%的 NaOCl 溶液或蒸馏水，浸泡时间分别为 1、10、100 或 1000 分钟（每种溶液和时间均有 5 颗牙）。使用预先用 15%碘化钾浸渍的纸尖测量氯的消耗。通过光电电子评估纸尖的颜色变化，测量其吸收根管内溶液后的红色值。将测量值与标准系列的 NaOCl 进行比较，最低浓度可达 0.001%（每种浓度均有 5 个纸尖）。
插入根管的纸尖的红色值受初始 NaOCl 浓度和时间的影响（双向方差分析，P <0.05）。如果将浓度高于 0.1%的 NaOCl 视为具有临床意义，那么 5.5%的 NaOCl 在根管中保持活性超过 100 分钟，而 1%的 NaOCl 在 10 至 100 分钟之间失去活性。
在延长的时间内，非搅拌的 NaOCl 溶液可以在人根管中保持生物活性。
