AimTo evaluate the effect of powder-to-water ratio on the retention characteristics of white mineral trioxide aggregate (MTA; Angelus, Londrina, Pr, Brazil) over time.,MethodsOne hundred and thirty-five root dentin slices from extracted single-rooted human mandibular premolar teeth were instrumented to achieve a diameter of 1.3mm. Three MTA groups were prepared using 4:1, 3:1, and 2:1 powder-to-water ratios. The samples were stored for 96h and 7 and 28days at 37 degrees C. The push-out bond strengths were measured using an Instron testing machine. Data were analyzed using two-way analysis of variance (anova) with Bonferroni correction.,ResultsThere was a statistically significant difference between the experimental groups at the 96-h and 7-day study periods (P=0.002). At 96h, the materials prepared at 2:1 ratio had the lowest bond strength than the samples prepared at the other two ratios (P<0.001). There was a significant difference between the findings at 96-h and 28-day study periods for 2:1 and 4:1 ratios. The highest bond strength value was found at 28days of exposure (P<0.001).,ConclusionThe powder-to-water ratio significantly interfered with the bond strength properties of white MTA.