Stabilizing Sodium Hypochlorite at High pH: Effects on Soft Tissue and Dentin
Holger Jungbluth, DMD,* Monika Marending, DMD,* Gustavo De-Deus, DDS, MS, PhD,† Beatrice Sener,* and Matthias Zehnder, PD, DMD, PhD*
Introduction:
When sodium hypochlorite solutions react with tissue, their pH drops and tissue sorption decreases. We studied whether stabilizing a NaOCl solu- tion at a high pH would increase its soft-tissue dissolu- tion capacity and effects on the dentin matrix compared with a standard NaOCl solution of the same concentration and similar initial pH.
Methods:
NaOCl solutions were prepared by mixing (1:1) a 10% stock solution with water (standard) or 2 mol/L NaOH (stabi- lized). Physiological saline and 1 mol/L NaOH served as the controls. Chlorine content and alkaline capacity of NaOCl solutions were determined. Standardized porcine palatal soft-tissue specimens and human root dentin bars were exposed to test and control solutions. Weight loss percentage was assessed in the soft-tissue dissolution assay. Three-point bending tests were per- formed on the root dentin bars to determine the modulus of elasticity and flexural strength. Values between groups were compared using one-way analysis of variance with the Bonferroni correction for multiple testing (a < .05).
Results:
Both solutions contained 5% NaOCl. One milliliter of the standard and the stabilized solution consumed 4.0 mL and 13.7 mL of a 0.1-mol/L HCl solution before they reached a pH level of 7.5, respectively. The stabilized NaOCl dis- solved significantly more soft tissue than the standard solution, and the pH remained high. It also caused a higher loss in elastic modulus and flexure strength (P < .05) than the control solutions, whereas the standard solution did not.
Conclusions:
NaOH-stabilized NaOCl solutions have a higher alkaline capacity and are thus more proteolytic than standard counterparts.
(J Endod 2011;37:693–696)
Key Words
Dentin, flexure strength, NaOCl, NaOH, tissue dissolution
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