Aim:This study aimed to compare, through dentin microhardness and colorimetric analysis, the chelating effect of 0.2% chitosan solubilized in different acids.Materials and Methods:The second and third cuts of the cervical region of maxillary central incisors were divided into four quadrants, resulting in eight specimens, which were treated with 50 μL of solution for 5 min according to their group (n = 10): GI – 0.2% chitosan solubilized in 1% acetic acid; GII – 0.2% chitosan solubilized in 3.3% citric acid; GIII – 0.2% chitosan solubilized in 0.00145% hydrochloric acid; and GIV – 0.2% chitosan solubilized in 0.00112% nitric acid. A control was made from the chelating properties of the following acids: GV – 3.3% citric acid, GVI – 0.00145% hydrochloric acid, GVII – 0.00112% nitric acid, and GVIII – control (distilled water). Afterward, they were subjected to the Knoop microhardness tester with a load of 10 g for 15 s, resulting in three indentations of the root canal toward the cement. The measurements obtained were subjected to the one-way ANOVA test followed by Tukey's test (α =0.05). Subsequently dispensing the chitosan solutions, the same were subjected to colorimetric analysis.Results:Chitosan solubilized in acetic acid, followed by chitosan in citric acid, provided a greater reducing effect compared to the other groups. Similar results were observed in the colorimetric analysis.Conclusion:It was concluded that the chelating ability of the chitosan solution solubilized in acetic acid is higher than solubilization in citric, hydrochloric, and nitric acids.

Objectives: Chitosan has been widely investigated and used. However, the literature does not refer to the shelf life of this solution. This study evaluated, through the colorimetric titration technique and an analysis of dentin micro-hardness, the shelf life of 0.2% chitosan solution. Materials and Methods: Thirty human canines were sectioned, and specimens were obtained from the second and third slices, from cemento-enamel junction to the apex. A 0.2% chitosan solution was prepared and distributed in 3 identical glass bottles (v1, v2, and v3) and 3 plastic bottles (p1, p2, and p3). At 0,7,15,30, 45, 60, 90, 120, 150, and 180 days, the specimens were immersed in each solution for 5 minutes (n = 3 each). The chelating effect of the solution was assessed by micro-hardness and colorimetric analysis of the dentin specimens. 17% EDTA and distilled water were used as controls. Data were analyzed statistically by two-way and Tukey-Kramer multiple comparison (α = 0.05). Results: There was no statistically significant difference among the solutions with respect to the study time (p = 0.113) and micro-hardness/time interaction (p = 0.329). Chitosan solutions and EDTA reduced the micro-hardness in a similar manner and differed significantly from the control group (p < 0.001). Chitosan solutions chelated calcium ions throughout the entire experiment. Conclusions: Regardless of the storage form, chitosan demonstrates a chelating property for a minimum period of 6 months. (Restor Dent Endod 2017;42(2):87-94)