Push-out bond strength of a nano-modified mineral trioxide aggregate

Introduction: To analyze the push-out bond strength of Angelus WMTA (Angelus Dental Products), a nano-modification of WMTA (Kamal Asgar Research Center) and Bioaggregate (Innovative Bioceramix). Methods: Sixty 2-mm-thick root sections were prepared from 60 single-rooted human teeth. The dentin disks were randomly divided into three groups (n = 20) and filled with Angelus WMTA, Nano-WMTA, or Bioaggregate, respectively. Push-out bond strength values of the specimens were measured by a universal testing machine and examined under scanning electron microscope at 9 40 magnification to determine the nature of the bond failure. The data were analyzed with a Kruskal-Wallis test. Results: The greatest mean for push-out bond strength (138.48 +/- 11.43 MPa) was observed for the nano-modification of WMTA. The values decreased to 110.73 +/- 11.19 and 25.64 +/- 5.27 MPa for Angelus WMTA and Bioaggregate, respectively. There were significant differences between the groups (P < 0.001). Inspection of the samples revealed the bond failure to be predominantly adhesive type except for the nano-modification group, as some samples also exhibited cohesive failures. Conclusions: It is concluded that the force needed for the displacement of the nano-modification of WMTA (NWMTA) was significantly higher than for Angelus WMTA and Bioaggregate.