Consequently, the fractured file is the only metal susceptible to dissolve at the polarization conditions used during the process. Because the root canals present limited dimensions, an inert microelectrode must be used to guarantee the contact with the fragment without creating a barrier to the solution. The results presented here showed current values of up to 2.25 mA, indicating that the platinum

tip with diameter equal to 0.1 mm is able to promote the proper contact to conduct the electrical current. The total electrical charge values generated during the polarization tests evidence a statistical difference among the 3 groups of fragments (ANOVA, P < .05). The larger is the diameter of the cross section of the exposed surface, the higher selleck kinase inhibitor is the total value of the electrical charge. These results showed that the current generated during the polarization depends on the surface area exposed to the solution. The results presented Galunisertib mw by Ormiga et al (28) also suggested that the current values depend on the area exposed to the solution, once the reduction of the area exposed to the solution was followed

by the decline of the current values during the entire test. It is important to note that the exposed area can be affected by the thickness of the platinum tip used as anode. The smaller is the point thickness, the higher is the area of the fragment exposed to the solution and faster is the dissolution. This factor points that the microelectrode to be developed must have the minimum possible thickness, even when promoting dissolution in large surfaces. In the present study, a platinum tip was manufactured from a wire of 0.1 mm in diameter. This diameter was selected by considering the minimum thickness necessary to maintain acceptable mechanical resistance. According to the results from the 360-minute polarization of fragments from group

Metalloexopeptidase D3, the cross-section area correspondent to the D3 of the K3 30.06 files is sufficient to generate current values of up to 1.50 mA. These current values indicate a significant dissolution of the fragment, which can be confirmed by the radiographic images obtained before and after the tests. However, because the current generated depends on the surface area exposed to the solution, other studies should be developed to test fragments with smaller cross-section diameter, like the D3 of a 25.04 file for example. During the tests, the current peaks showed a gradual reduction during the initial 120 minutes and did not surpass 0.30 mA from this moment. This gradual decrease can be related to the reduction of the area exposed to the solution during the test, once the active portion of the files presents a taper. However, the current decrease was concentrated in the initial 120 minutes of the test, and the constant taper of the K3 files should have caused a gradual decrease of current during the entire test.