Comparative evaluation of calcium hypochlorite and sodium hypochlorite on soft-tissue dissolution

Introduction: The aim of this study was to compare in vitro the tissue-dissolution properties of 5% and 10% calcium hypochlorite (Ca(OCl) ) with two concentrations (1.36% and 4.65%) of proprietary sodium hypochlorite (NaOCl) on bovine muscle tissue. Methods: The available chlorine concentration of each solution was determined using iodometric titration. Tissue specimens from bovine muscle were weight adjusted (50 ± 5 mg). Ten tissue specimens in each group were immersed in 5 mL each test solution, removed after 5 minutes, blotted dry, and weighed. The process was repeated every 5 minutes with a fresh 5-mL aliquot of the test solution for 60 minutes or until complete tissue dissolution, whichever was quickest. The percentage weight loss of the specimens was calculated over the experimental period. Results: Available chlorine concentrations of the irrigants ranged from 1.36% to 4.65%. All solutions dissolved tissue completely after 60 minutes except 5% Ca(OCl) (99.4% dissolution). Between the 35- and 60-minute test readings, there were no significant differences between the solutions. Chlorax (4.65% NaOCl) (Cerkamed Group, Nisko, Poland) dissolved tissue quicker during the first 35 minutes (P <.05). In this period, the weight loss with 10% Ca(OCl) differed from Chlorax at all time intervals except at 5 and 35 minutes (P <.05); 5% Ca(OCl) showed no significant differences with 10% Ca(OCl) and Tesco bleach (1.36% NaOCl) (Tesco Stores Ltd, Chestnut, UK) in the first 35 minutes except at the 5-minute measurement. Conclusions: Within the limitations of this study, Chlorax (4.65% NaOCl) dissolved tissue faster than the Ca(OCl) solutions and Tesco thin bleach (1.36% NaOCl) over the first 35 minutes, but there were no significant differences among the solutions thereafter.