An Evaluation of the Accuracy of Labeling of Percent Sodium Hypochlorite on Various Commercial and Professional Sources: Is Sodium Hypochlorite from These Sources Equally Suitable for Endodontic Irrigation?

• Published in: Journal of endodontics Vol. 40; no. 12; pp. 2049 - 2052
• Main Authors: van der Waal, Suzette V., DDS, van Dusseldorp, Nilai E., MSc, de Soet, Johannes J., PhD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-12-2014
• Subjects: Chemistry, Pharmaceutical; Chlorine - analysis; Concentration; Dentistry; Drug Labeling - standards; Drug Stability; Drug Storage; Endocrinology & Metabolism; endodontic; free available chlorine; Humans; irrigation; Materials Testing; Root Canal Irrigants - analysis; Root Canal Irrigants - standards; shelf life; sodium hypochlorite; Sodium Hypochlorite - analysis; Sodium Hypochlorite - standards; Temperature; Time Factors; Titrimetry - methods; Water - chemistry; endodontic; free available chlorine; irrigation; Concentration; shelf life; sodium hypochlorite
• ISSN: 0099-2399; 1878-3554
• DOI: 10.1016/j.joen.2014.08.021

Abstract Introduction The shelf life of sodium hypochlorite (NaOCl) is limited, and a previous article showed that there can be a discrepancy between the expected concentration of free available chlorine (FAC) and the actual FAC concentration in NaOCl solutions intended for endodontic irrigation. The current study investigates the FAC content of domestic and professional NaOCls and evaluates the influences of dilution and storage on FAC concentration. Methods First, domestic and professional NaOCls not obtained from manufacturers were iodometrically titrated. Then, NaOCls were diluted with demineralized water or tap water and stored at 4°C or 18°C and analyzed at baseline and 2 and 22 weeks. Statistical analyses included paired samples, independent samples t tests and repeated multivariate analysis of variance. Correlations were calculated with the Pearson or Spearman rank correlation test. A P  < .05 was considered significant. Results Label specifications of domestic NaOCl were very imprecise (ie, <5% NaOCl). Domestic NaOCl contained 1.8%–3.5% NaOCl (w/v). Professional NaOCl varied from 14.3% relative less FAC than specified on the label to 23.5% relative more FAC than specified. After 22 weeks, the relative average loss of FAC in all conditions was 5.4% FAC ( P  = .002). Dilution, diluents, or storage temperature had no effect on the decline of FAC caused by aging. Conclusions There is a great variation in NaOCl concentrations, with domestic NaOCl being the least accurate. NaOCl can be stored up to 5 months. The FAC concentration of domestic NaOCl is unpredictable, and, therefore, it appears less suitable for clinical application as root canal irrigant.