title: Effect of acidic environment on dislocation resistance of endosequence root repair material and mineral trioxide aggregate.
abstract: OBJECTIVE
  The aim of this study was to compare the effect of an acidic environment on dislocation resistance (push-out bond strength) of EndoSequence Root Repair Material (ERRM putty and ERRM paste), a new bioceramic-based material, to that of mineral tri-oxide aggregate (MTA).
  
  
  METHODS
  One-hundred twenty root dentin slices with standardized canal spaces were divided into 6 groups (n = 20 each) and filled with tooth-colored ProRoot MTA (groups 1 and 2), ERRM putty (groups 3 and 4), or ERRM paste (groups 5 and 6). The specimens of groups 1, 3, and 5 were exposed to phosphate buffered saline (PBS) solution (pH=7.4) and those of groups 2, 4, and 6 were exposed to butyric acid (pH= 4.4). The specimens were then incubated for 4 days at 37°C. The push-out bond strength was then measured using a universal testing machine. Failure modes after the push-out test were examined under a light microscope at ×40 magnification. The data for dislocation resistance were analyzed using the t-test and one-way analysis of variance.
  
  
  RESULTS
  In PBS environment (pH=7.4), there were no significant differences among materials (P=0.30); but the mean push-out bond strength of ERRM putty was significantly higher than that of other materials in an acidic environment (P<0.001). Push-out bond strength of MTA and ERRM paste decreased after exposure to an acidic environment; whereas ERRM putty was not affected by acidic pH. The bond failure mode was predominantly cohesive for all groups except for MTA in an acidic environment; which showed mixed bond failure in most of the specimens.
  
  
  CONCLUSIONS
  The force needed for dislocation of MTA and ERRM paste was significantly lower in samples stored in acidic pH; however, push-out bond strength of ERRM putty was not influenced by acidity.
authors.affiliation: Associate Professor, Dental Research Center Dentistry Research Institute, Department of Endodontics, School of Dentistry Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Noushin
authors.initials: N
authors.lastname: Shokouhinejad
authors.affiliation: Associate Professor, Dental Research Center Dentistry Research Institute, Department of Endodontics, School of Dentistry Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Kazem Ashofteh
authors.initials: KA
authors.lastname: Yazdi
authors.affiliation: Assistant Professor, Dental Research Center Dentistry Research Institute, Department of Endodontics, School of Dentistry Tehran University of Medical Sciences, Tehran, Iran ; Endodontology Research Group, School of Dentistry, Cardiff University, Heath Park, Cardiff, UK.
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Nekoofar
authors.affiliation: Dental Student, School of Dentistry Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Shakiba
authors.initials: S
authors.lastname: Matmir
authors.affiliation: Assistant Professor, Dental Research Center Dentistry Research Institute, Department of Endodontics, School of Dentistry Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mehrfam
authors.initials: M
authors.lastname: Khoshkhounejad
keywords: Acid; Endosequence Root Repair Material; Mineral Trioxide Aggregate; pH, Dislocation