Effect of Sodium Hypochlorite on Dentin Mechanical Properties. Systematic Review

Objectives: The aim of this article was to carry out a systematic review of the effect of sodium hypochlorite (NaOCl) upon the mechanical properties of coronary, pulp chamber, and/or root dentin. Methods: The authors searched the Cochrane Library, Pubmed and the Web of Science for papers published in 1984-2007. The main search terms used were: dentin, coronary dentin, root dentin, sodium hypochlorite, mechanical analysis, elastic modulus, hardness, shear bond strength, and tensile strength. The inclusion criteria were: studies that evaluated the effect of NaOCl pretreatment on coronary resin-dentin bond, the influence of NaOCl solution on adhesion to pulp chamber dentin, and the effect of NaOCl solution, used as an irrigant in endodontics, on the mechanical properties of root dentin. Exclusion criteria were studies that had used NaOCl as storage medium for resin-dentin bond degradation, had evaluated the NaOCl effect on the force required for fracturing root dentin, and those that had not verified the direct effect of NaOCl solution. Results: The selected papers were assessed with a score (A to C), according to predetermined criteria. Of the 46 papers that were critically assessed, 40 studies were included in the project critical appraisal. One paper was classified as grade A, 27 as grade B, and 12 as grade C. Conclusions: Based on this systematic review, the authors suggest that there is moderate evidence that the sodium hypochlorite pre-treatment improves the bond strength of coronary dentin; however, when used as an endodontic irrigant, it alters the mechanical properties of pulp chamber and root dentin.