van der Waal Suzette, Connert Thomas, Laheij Alexa, de Soet Johannes, Wesselink Paul
Quintessence Int. 2014 Jun;45(6):467-74. doi: 10.3290/j.qi.a31805.
Sodium hypochlorite (NaOCl) is an important tool in root canal disinfection although it is well known that the shelf-life of NaOCl is limited. In this study, NaOCl solutions that were collected from dental practices and were intended for endodontic irrigation were investigated to see whether they contained the expected concentration of free available chlorine.
NaOCl solutions were collected from dental practices. The concentration of available chlorine per sample was determined with iodometric titration and the pH was measured. Each participating dentist completed a questionnaire that requested data on a range of issues relating to the assumed concentration of NaOCl and handling of the sample.
Eighty-four samples with questionnaires were received. NaOCl was purchased from supermarkets and drugstores (36%), dental suppliers (48%), or pharmacies (16%). The median expected concentration was 2% (n = 36). On average, 27% less available chlorine was measured than the dentist assumed was in the sample (P < .001). Fifteen percent of samples contained less than 1% available chlorine, which is needed for tissue dissolution and disinfection. The average pH was 11.5.
The greatest differences in concentrations were found in NaOCl sourced from supermarkets or drugstores. Future studies should elucidate the cause of this discrepancy.
In the meantime it is recommended to purchase NaOCl from professional suppliers, because this group showed the most reliable content of free available chlorine.
次氯酸钠（NaOCl）是根管消毒的重要工具，尽管众所周知其保质期有限。本研究对从牙科诊所收集的用于根管冲洗的NaOCl溶液进行调查，以确定其游离有效氯浓度是否符合预期。
从牙科诊所收集NaOCl溶液。用碘量滴定法测定每个样品中有效氯的浓度并测量pH值。每位参与的牙医填写一份问卷，该问卷要求提供有关NaOCl假定浓度和样品处理等一系列问题的数据。
共收到84份附有问卷的样品。NaOCl购自超市和药店（36%）、牙科供应商（48%）或药房（16%）。预期浓度的中位数为2%（n = 36）。测得的有效氯平均比牙医假定的样品浓度低27%（P <.001）。15%的样品有效氯含量低于1%，而组织溶解和消毒需要该浓度。平均pH值为11.5。
在购自超市或药店的NaOCl中发现浓度差异最大。未来的研究应阐明这种差异的原因。
同时，建议从专业供应商处购买NaOCl，因为该组显示的游离有效氯含量最可靠。
