![]() NaOCl cannot decrease calcium chelating or smear layer removal of EDTA and CA. concluded that EDTA may cause NaOCl to lose its tissue-dissolving ability. Using spectroscopy, they showed that both compounds depleted the solution from chlorine after only 5 minutes. evaluated interactions of gel-type preparations of chelators containing 10% urea peroxide and 15% EDTA with 1% NaOCl. They also showed that the available chlorine loss may be 80%. concluded that when NaOCl was combined with EDTA, free chlorine may decrease to 0 in period of 60 minutes. This means that adding EDTA to NaOCl may cause lower levels of chlorine gas. Baumgartner and Ibay showed that pH reduction in NaOCl may cause chlorine gas release. However, when mixed in a 1:3 ratio, pH was stable during 48-hour time, possibly because of immediate interaction between solutions. Įqual proportions of 1-2% NaOCl with 17% EDTA may result in pH of 8.0 from an initial value of 10 after 48 hours. This may affect free chlorines in solution and increase in chlorine gas and hypochlorous acid, subsequently decreases the hypochlorite ion. Īdding EDTA to NaOCl can decrease the pH of NaOCl in a time-dependent manner. The fact that the proportion of chloride ions decreases in the solution does not mean that the solution will lose its antibacterial effect. But at a lower pH, the high proportion of hypo chloric acid is explanation of the antibacterial effect. A high concentration of chloride ions produces high cytotoxicity, which explains the excellent antibacterial effect. ![]() The antibacterial effect of NaOCl can be achieved in two different ways. Combination of NaOCl and CHX has been proposed to increase their antibacterial action. Chlorhexidine (CHX) is a cationic bis-guanide with residual antibacterial activity. Substantive antimicrobial agents are attached to hydroxyapatite containing tissues ( i.e. One of the other drawbacks of NaOCl is the lack of substantivity. CA is also an organic acid normally used in endodontic therapy at 10-50% concentrations with pH 1-2. EDTA is used at10-17% concentrations its pH is modified from original value of 4 to values up to 8 for increasing its chelating activity. Therefore, adjunctive use of a chelating agent like ethylene-diamine tetra-acetic acid (EDTA) or citric acid (CA) has been proposed in order to remove the smear layer created after root canal preparation. One important drawback of NaOCl is its inability forsmear layer removal. NaOCl is available as 1-15% aqueous solutions with alkaline pH (around 11). ![]() 2. RATIONALE FOR COMBINING SODIUM HYPOCHLORITE (NaOCl) AND OTHER IRRIGANTSĪs NaOCl has excellent antimicrobial action and also tissue solubility, it has been used in endodontics as the most common irrigation solution. ![]()
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