title: Effect of pH on compressive strength of some modification of mineral trioxide aggregate.
abstract: OBJECTIVE
  Recently, it was shown that NanoMTA improved the setting time and promoted a better hydration process which prevents washout and the dislodgment of this novel biomaterial in comparison with WTMA. This study analyzed the compressive strength of ProRoot WMTA (Dentsply), a NanoWMTA (Kamal Asgar Research Center), and Bioaggregate (Innovative Bioceramix) after its exposure to a range of environmental pH conditions during hydration.
  
  
  METHODS
  After mixing the cements under aseptic condition and based on the manufacturers` recommendations, the cements were condensed with moderate force using plugger into 9 × 6 mm split molds. Each type of cement was then randomly divided into three groups (n=10). Specimens were exposed to environments with pH values of 4.4, 7.4, or 10.4 for 3 days. Cement pellets were compressed by using an Instron testing machine. Values were recorded and compared. Data were analyzed by using one-way analysis of variance and a post hoc Tukey's test.
  
  
  RESULTS
  After 3 days, the samples were solid when probed with an explorer before removing them from the molds. The greatest mean compressive strength 133.19 ± 11.14 MPa was observed after exposure to a pH value of 10.4 for NanoWMTA. The values decreased to 111.41 ± 8.26 MPa after exposure to a pH value of 4.4. Increasing of pH had a significant effect on the compressive strength of the groups (p<0.001). The mean compressive strength for the NanoWMTA was statistically higher than for ProRoot WMTA and Bioaggregate (p<0.001). Moreover, increasing of pH values had a significant effect on compressive strength of the experimental groups (p<0.001).
  
  
  CONCLUSIONS
  The compressive strength of NanoWMTA was significantly higher than WMTA and Bioaggregate; the more acidic the environmental pH, the lower was the compressive strength.
authors.affiliation: Department of Dental Material, Dental School, Azad University, Tehran Branch and Kamal Asgar Research Center, Tehran, Iran
authors.forename: Mohammad-Ali
authors.initials: MA
authors.lastname: Saghiri
authors.forename: Franklin
authors.initials: F
authors.lastname: Garcia-Godoy
authors.forename: Armen
authors.initials: A
authors.lastname: Asatourian
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Lotfi
authors.forename: Sepideh
authors.initials: S
authors.lastname: Banava
authors.forename: Kaveh
authors.initials: K
authors.lastname: Khezri-Boukani
mesh_terms: D017607:Aluminum Compounds; D017610:Calcium Compounds; D002126:Calcium Hydroxide; D019245:Compressive Strength; D003738:Dental Cements; D004338:Drug Combinations; D006863:Hydrogen-Ion Concentration; D006882:Hydroxyapatites; D008422:Materials Testing; D010087:Oxides; D019904:Polymethyl Methacrylate; D017640:Silicates
chemical_list: D017607:Aluminum Compounds; C557009:BioAggregate; D017610:Calcium Compounds; D003738:Dental Cements; D004338:Drug Combinations; D006882:Hydroxyapatites; D010087:Oxides; D017640:Silicates; C086631:mineral trioxide aggregate; C035124:CMW cement; D019904:Polymethyl Methacrylate; D002126:Calcium Hydroxide