Single dose of 0 mg/kg (control group), 6 mg/kg (low-dose group), and 60 mg/kg (high-dose group) of MA (Maleic acid) with DDW (double deionized water) as the vehicle were administered to SD rats via oral gavage.

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). Maleic acid reduced the microhardness of root dentin similar to EDTA but increased the surface roughness significantly more than EDTA.