Push-out Bond Strength of Mineral Trioxide Aggregate in the Presence of Alkaline pH

Introduction: The aim of this study was to evaluate the effect of a range of alkaline pH values on the push-out strength of white mineral trioxide aggregate (WMTA). Methods: The standardized lumens of root slices prepared from extracted single-rooted human teeth were filled with white Pro Root MTA. The specimens were then randomly divided into 4 groups (n = 20) and wrapped in pieces of gauze soaked in synthetic tissue fluid (STF) (pH, 7.4) and STF buffered in potassium hydroxide at pH values of 8.4, 9.4, or 10.4. The samples were incubated for 3 days at 37 degrees C. The push-out bond strengths were then measured by using a universal testing machine. Failure modes after the push-out test were examined under a light microscope at x40 magnification. The data were analyzed by using one-way analysis of variance and Tukey post hoc tests. Results: The greatest (9.46 +/- 0.63 MPa) and lowest (5.68 +/- 0.83 MPa) mean push-out bond strengths were observed after exposure to pH values of 8.4 and 10.4, respectively. There were significant differences between the groups (P = .001). The bond failure was adhesive for all experimental groups. Conclusions: Push-out bond strength of WMTA could be influenced by different alkaline pH values. (J Endod 2010;36:1856-1859)