Evaluation of the effect of maleic acid and ethylenediaminetetraacetic acid on the microhardness and surface roughness of human root canal dentin

Introduction: The aim of this in vitro study was to evaluate the effect of 7% maleic acid and 17% EDTA solutions on the microhardness and the surface roughness of human root canal dentin. Methods: Forty-five extracted human maxillary central incisors were sectioned longitudinally into a total of 90 segments, were embedded in auto polymerizing acrylic resin, and were grounded flat with silicon carbide abrasive papers. Based on the test solutions used, samples were divided randomly into three groups: (1) the EDTA group, 1 mL of 17% EDTA for 1 minute (n = 30), (2) the maleic acid group, 1 mL of 7% maleic acid for 1 minute (n = 30), and (3) the control group, 1 mL of 0.9% saline for 1 minute (n = 30). Every group was then divided into two subgroups of 15 specimens each. In group 1a, 2a, and 3a, specimens were used to determine the microhardness of the root canal dentine in the coronal, middle, and apical third using Vicker's hardness tester. In groups 1b, 2b, and 3b, specimens were used for the determination of surface roughness of the root canal dentine using a roughness tester (Surtronic, Leicester, England). The data were statistically analyzed using the Kruskall Wallis and Mann Whitney U tests. Results: There was no significant difference between EDTA and maleic acid in the reduction of microhardness. The increase in roughness was significantly greater with maleic acid when compared with EDTA. Conclusion: Maleic acid reduced the microhardness of root dentin similar to EDTA but increased the surface roughness significantly more than EDTA.