Shelf life, dissolving action, and antibacterial activity of a neutralized 2.5% sodium hypochlorite solution

Stabilizing Sodium Hypochlorite at High pH: Effects on Soft Tissue and Dentin

“…The reason for this is two-fold: unaltered sodium hypochlorite solutions are alkaline per se, and neutralized or acidified solutions are unstable and thus cannot be stored or marketed that way (10). This study tested the hypothesis that adding more alkali to a standard (and thus already alkaline) solution would increase its proteolytic effect in contact with tissues.…”

“…However, unaltered sodium hypochlorite solutions have a pH in the range of 11.5 to 12.5, depending on their concentration. Lowering the pH to 7.5 using hypochlorous acid makes the resulting solution unstable and more cytotoxic than a counterpart with equal amounts of available chlorine at pH 12 (10,11). Moreover, it is questionable whether the differences in antimicrobial effect between a neutralized sodium hypochlorite solution (pH 7.5) and a counterpart at pH 12 is clinically relevant in the concentration range typically applied during root canal treatment (10).…”

“…Lowering the pH to 7.5 using hypochlorous acid makes the resulting solution unstable and more cytotoxic than a counterpart with equal amounts of available chlorine at pH 12 (10,11). Moreover, it is questionable whether the differences in antimicrobial effect between a neutralized sodium hypochlorite solution (pH 7.5) and a counterpart at pH 12 is clinically relevant in the concentration range typically applied during root canal treatment (10). One potentially important aspect in this context is that neutralized or acidified sodium hypochlorite solutions dissolve considerably less soft tissue than unaltered counterparts (11,12).…”

Assessment of residual active chlorine in sodium hypochlorite solutions after dissolution of porcine incisor pulpal tissue

“…9 The ability of NaOCl to dissolve protein and kill microbes has been shown to vary with changes in the pH of NaOCl solutions. [10][11][12] Experiments by Moorer and Wesselink and Spano et al measured residual active chlorine levels in NaOCl solutions after the dissolution of various forms of protein. 5,6 Invariably, where active chlorine was calculated in the NaOCl solutions tested, iodometric titration was used, there being no specific test for the presence of hypochlorite ion in NaOCl.…”

Physicochemical and Pulp Tissue Dissolution Properties of Some Household Bleach Brands Compared with a Dental Sodium Hypochlorite Solution

“…Further factors are pH (5,6), alkaline capacity (7), and contact time (4). Stojicic et al (8) claim that surface tension, which is lowered in some commercial products explicitly sold for the dental market, also affects the performance of NaOCl solutions.…”