Comparative evaluation of human pulp tissue dissolution by different concentrations of chlorine dioxide, calcium hypochlorite and sodium hypochlorite: An in vitro study
!! "Results showed *5.25% NaOCl to be most effective* (at dissolving tissue) at both time intervals followed by 2.5% NaOCl at 60 minutes, 10%Ca(OCl)2 and 13% ClO2 at 60 minutes. Least amount of tissue dissolving ability was demonstrated by 5% Ca(OCl)2 and 5% ClO2 at 30 minutes." *****"Mean tissue dissolution by ClO2 was significantly less than NaOCl. The reason for this might also be the low pH of ClO2 as compared to high pH (pH = 12) of NaOCl. In a study by Nishikiori et al,[18] the pH of ClO2 was raised upto 12 by using NaOH and it was found equivalent to NaOCl for dissolving bovine pulp tissue. But according to Deininger et al.[19] ClO2 exhibits biocidal efficacy only over a pH range of 3-9. Between pH 4-7, chlorine exists predominantly as HClO, the active moiety responsible for bacterial inactivation, whereas above pH 9, OCl− predominates.[20] Also the addition of NaOH will result in making the aqueous solution of ClO2 ineffective by breaking it down into sodium chlorate, sodium chlorite and water. Among the ClO2 group, large amount of mean tissue dissolution was demonstrated by 13% ClO2 at 60 minutes.5% ClO2 showed lower pulp dissolving capacity at 30 minutes, followed by 5% ClO2 at 60 minutes and 13% ClO2 at 30 minutes, which were comparable. *****Studies have suggested that !!!!!!!lower the pH !!!!, more time was needed for solution contact for tissue dissolution.***** [6] This might be the reason for less effectiveness of ClO2 in dissolution of pulp tissue at 30 minutes than at 60 minutes. "
