Leonardo Natália Gomes e Silva, Carlotto Israel Bangel, Luisi Simone Bonato, Kopper Patrícia Maria Poli, Grecca Fabiana Soares, Montagner Francisco
Post Graduation Program in Dentistry, Dental School, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
Department of Conservative Dentistry, Dental School, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
J Endod. 2016 Apr;42(4):641-5. doi: 10.1016/j.joen.2016.01.006. Epub 2016 Mar 2.
The aim of this study was to evaluate the pH and the available chlorine content from sodium hypochlorite (NaOCl) and calcium hypochlorite (Ca[OCl]2) solutions stored in different conditions and time periods and the surface tension of Ca(OCl)2 solutions in comparison with NaOCl.
Solutions at 0.5%, 1%, 2.5%, and 5.25% concentrations were prepared. The pH level and the available chlorine content of freshly prepared solutions and solutions stored for 30, 60, and 90 days at 25°C, 4°C, or 37°C were evaluated in a digital pH meter and by titration, respectively. Surface tension was tested using a Du Nouy tensiometer (Sigma 702, Force Tensiometer; Attension, Espoo, Finland). Descriptive and inferential statistical analyses were performed.
A precipitate formed by 2.5% and 5.25% Ca(OCl)2 solutions was observed. Ca(OCl)2 showed a higher concentration of available chlorine than NaOCl. Both 2.5% and 5.25% NaOCl and Ca(OCl)2 had a decrease in the available chlorine content when compared with freshly prepared solutions; 0.5% and 1% NaOCl tend to have a lower pH compared with 0.5% and 1% Ca(OCl)2. NaOCl, 5.25%, showed higher pH compared with 5.25% Ca(OCl)2. NaOCl and Ca(OCl)2 in 0.5% and 1% concentrations tend to show a reduced pH level, whereas 2.5% and 5.25% solutions showed an increase in pH. The heat contributed to the instability of the solutions. NaOCl showed lower surface tension values than Ca(OCl)2.
Ca(OCl)2 solutions are extremely alkaline and tend to have more available chlorine content than NaOCl but have a higher surface tension than NaOCl. Regarding the available chlorine content, these solutions tend to be stable to 30 days of storage when kept at 4°C or at 25°C.
本研究的目的是评估在不同条件和时间段下储存的次氯酸钠（NaOCl）和次氯酸钙（Ca[OCl]₂）溶液的pH值和有效氯含量，以及与NaOCl相比Ca(OCl)₂溶液的表面张力。
制备浓度为0.5%、1%、2.5%和5.25%的溶液。分别使用数字pH计和滴定法评估新制备溶液以及在25°C、4°C或37°C下储存30、60和90天的溶液的pH值和有效氯含量。使用杜诺伊张力计（Sigma 702，力张力计；Attension，埃斯波，芬兰）测试表面张力。进行描述性和推断性统计分析。
观察到2.5%和5.25%的Ca(OCl)₂溶液形成沉淀。Ca(OCl)₂的有效氯浓度高于NaOCl。与新制备的溶液相比，2.5%和5.25%的NaOCl和Ca(OCl)₂的有效氯含量均有所下降；0.5%和1%的NaOCl的pH值往往低于0.5%和1%的Ca(OCl)₂。5.25%的NaOCl的pH值高于5.25%的Ca(OCl)₂。0.5%和1%浓度的NaOCl和Ca(OCl)₂的pH值往往会降低，而2.5%和5.25%的溶液pH值会升高。热量导致溶液不稳定。NaOCl的表面张力值低于Ca(OCl)₂。
Ca(OCl)₂溶液具有极强的碱性，有效氯含量往往比NaOCl高，但表面张力比NaOCl高。关于有效氯含量，这些溶液在4°C或25°C下储存30天时往往较为稳定。
