The average impedance measured at the apical, middle, and basal electrode channels all achieved good results (<5kΩ), the lowest average impedance was measured at the dip DEX group with a value of 3.97 ± 0.88 (kΩ), followed by the pump DEX group with a value of 4.27 ± 1.41 (kΩ), the highest was the group without DEX with a result of 4.48 ± 1.28 (kΩ), however the difference between the groups was not statistically significant with p> 0, 05.