The Effect of Temperature and pH Variations on the Surface Tension of EDTA Solutions

Introduction: Surface tension of a liquid is one of the major factors that affect the wetting of a solid. The reduction in surface tension could improve the contact of irrigants with the dentinal walls of the root canal system. This in vitro study was conducted to evaluate the effect of pH and temperature variations on the surface tension of EDTA solutions. Methods: Three solutions, 17% EDTA, REDTA, and EDTA-T, were prepared and adjusted to have a pH of 5.5, 7.5, and 10.5. The surface tension of the test solutions was measured at 22 degrees C by the pendant drop technique, and the measurement was repeated after heating the solution at 37 degrees C. Differences among the experimental groups were statistically analyzed using three-way analysis of variance followed by the Bonferroni test for pair-wise comparison. Results: The results of this study showed that there were significant differences in the surface tension values of solutions depending on the pH and temperature (P <.001). The surface tension level of the EDTA solution dramatically decreased when surfactant was added to the EDTA solution in both pH and temperature variations (P <.001). The increased temperature significantly altered the surface tension value at a pH of 5.5 of all EDTA solutions, at a pH of 7.5 of EDTA and REDTA solutions, and at a pH of 10.5 of only REDTA solution (P <.01). Conclusions: It was concluded that the surface tension of EDTA with and without surfactant is influenced by pH and temperature. (J Endod 2011;37:825-827)