Comparison of the surface tension of 5.25% sodium hypochlorite solution with three new sodium hypochlorite-based endodontic irrigants.

To investigate the surface tension characteristics of 5.25% sodium hypochlorite and three recently introduced sodium hypochlorite solutions, which had been modified to reduce their surface tension: Chlor-Xtra, Hypoclean A and Hypoclean B. Freshly produced MilliQ water was used as a reference liquid. All measurements of surface tension were taken by the Wilhelmy plate technique, using a Cahn DCA-322 Dynamic Contact Angle Analyzer at the temperature of 22 °C. A glow-discharge cleaned glass slide was immersed in 5 mL of the test liquid in a beaker cleaned with hot chromic acid, rinsed with MilliQ water and finally air plasma-cleaned in a glow-discharge reactor. The force on the glass slide was recorded continuously by the instrument software as the beaker was raised and withdrawn at the constant speed of 40 micron/s, until at least 1 cm of the glass slide was immersed. The typical accuracy was 0.5 mJ m(-2). For each sample, fifteen measurements were taken, and mean values were calculated. A Kruskal-Wallis anova analysis, followed by Mann-Whitney's U rank sum test for pair-wise comparisons, was used to compare surface tension values. Statistical significance was set at α = 0.05. MilliQ water (72.13 mJ m(-2)) and 5.25% sodium hypochlorite (48.90 mJ m(-2) ) had the highest surface tension values (P < 0.01) compared to Chlor-Xtra (33.14 mJ m(-2)), Hypoclean B (30.00 mJ m(-2) ) and Hypoclean A (29.13 mJ m(-2)). Hypoclean A had the lowest surface tension (P < 0.01). The new 5.25% sodium hypochlorite solutions modified with surfactants, Hypoclean A and Hypoclean B, had surface tension values that were significantly lower (P < 0.01) than Chlor-Xtra and 5.25% NaOCl. Because of their low surface tension and increased contact with dentinal walls, these new irrigants have the potential to penetrate more readily into uninstrumented areas of root canal system as well as allow a more rapid exchange with fresh solution, enabling greater antimicrobial effectiveness and enhanced pulp tissue dissolution ability.