Bactericidal and wound-healing properties of sodium hypochlorite solutions: The 1991 lindberg award

Toxic effects of sodium hypochlorite on wound healing elements have been confined to a restricted range of sodium hypochlorite concentrations. We investigated concentrations of sodium hypochlorite for antibacterial activity and tissue toxicity at varying time intervals. We attempted to find the efficacious therapeutic concentration that was both microbicidal and nontoxic. Gram-negative and gram-positive isolates (0.1/ml of 1 × 108/ml) were introduced into various concentrations of buffered and unbuffered sodium hypochlorite solutions for determinations of bactericidal activity at 5-, 10-, 15-, and 30-minute intervals. Concentrations of sodium hypochlorite were 0.25%, 0.025%, and 0.0125%. In vitro assays with fibroblasts at the same concentrations were also performed to determine toxicity at the same time intervals. An in vivo incisional model was also used to determine the effects of sodium hypochlorite therapy on wound healing. Bactericidal effects were observed for concentrations as low as 0.025%. Tissue toxicity, both in vitro and in vivo, was observed at concentrations of 0.25% but not at a concentration of 0.025%. Although concentrations below this level were nontoxic, they were not bactericidal. Therefore a modified “Dakin’s” solution at a concentration of 0.025% is therapcutically efficacious as a fluid dressing, since it preserves bactericidal properties and eliminates the detrimental potential on wound healing.