Inhibition of endogenous dentin matrix metalloproteinases by ethylenediaminetetraacetic acid

Introduction: Endogenous dentin matrix metalloproteinases (MMPs) contribute to extracellular collagen matrix degradation in hybrid layers after adhesive dentin bonding procedures. Endodontic irrigants, including chlorhexidine and ethylenediaminetetraacetic acid (EDTA), might help protect the hybrid layer from this process. The objective of the present study was to determine the exposure time necessary for EDTA to inactivate endogenous MMP activity in human dentin. Methods: Dentin beams (2 × 1 × 3 mm) were prepared from mid-coronal dentin of extracted third molars. The beams were demineralized in 10 wt% phosphoric acid, which also activated endogenous MMPs, and were divided into 4 experimental groups on the basis of exposure time to 17% EDTA (0, 1, 2, or 5 minutes). A generic colorimetric MMP assay measured MMP activity via absorbance at 412 nm. Data were evaluated by Kruskal-Wallis analysis of variance, followed by Dunn pair-wise comparisons at α = 0.05. Results: All exposure times resulted in significant inhibition (P <.001) compared with unexposed controls. Specifically, percent inhibition for 1-, 2-, and 5-minute exposure times was 55.1% ± 21.5%, 72.8% ± 11.7%, and 74.7% ± 19.7%, respectively. Conclusions: Seventeen percent EDTA significantly inhibits endogenous MMP activity of human dentin within 1-2 minutes. This might minimize hybrid layer degradation after resin bonding procedures in the root canal space.