title: The effect of various mixing and placement techniques on the compressive strength of mineral trioxide aggregate.
abstract: BACKGROUND
  The aim of this study was to evaluate the effect of various mixing techniques including mechanical and manual mixing as well as the effect of ultrasonic agitation during placement on the compressive strength of mineral trioxide aggregate (MTA).
  
  
  METHODS
  Tooth-colored ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland) and white MTA Angelus (Angelus Soluções Odontologicas, Londrina, Brazil) were used. One gram of each powder was mixed with a 0.34-g aliquot of distilled water. Specimens were mixed either by mechanical mixing of capsules for 30 seconds at 4,500 rpm or by a saturation technique and the application of a condensation pressure of 3.22 MPa for 1 minute. Half of the specimens were placed in stainless steel molds and agitated using indirect ultrasonic activation. All specimens were subjected to compressive strength testing after 4 days.
  
  
  RESULTS
  The compressive strength values of ProRoot MTA were significantly greater than those of MTA Angelus (P < .05). The highest compressive strength values were recorded from ProRoot MTA samples that were mixed mechanically and placed using ultrasonic activation (mean = 101.71 MPa), whereas the lowest values were recorded for MTA Angelus samples that were mixed manually and placed without ultrasonic activation (mean = 53.47 MPa). Ultrasonically agitated groups had higher compressive strength values (P < .001). The specimens mixed mechanically had higher compressive strength values than those mixed manually (P < .05).
  
  
  CONCLUSIONS
  The compressive strength values of ProRoot MTA were significantly greater than those of MTA Angelus. Mechanical mixing enhanced the compressive strength of the material. Regardless of the mixing techniques applied, ultrasonic agitation improved the compressive strength of the material.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Marmara University, Istanbul, Turkey.
authors.forename: Fatima B
authors.initials: FB
authors.lastname: Basturk
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Nekoofar
authors.forename: Mahir
authors.initials: M
authors.lastname: Günday
authors.forename: Paul M
authors.initials: PM
authors.lastname: Dummer
mesh_terms: D017607:Aluminum Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D001729:Bismuth / Q000737:chemistry*; D017610:Calcium Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D019245:Compressive Strength; D003738:Dental Cements / Q000138:chemical synthesis / Q000737:chemistry*; D004338:Drug Combinations; D006801:Humans; D008422:Materials Testing; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry*; D011312:Pressure; D012387:Root Canal Filling Materials / Q000138:chemical synthesis / Q000737:chemistry*; D017640:Silicates / Q000138:chemical synthesis / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D014465:Ultrasonics; D014867:Water / Q000737:chemistry
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D003738:Dental Cements; D004338:Drug Combinations; C475480:MTA-Angelus; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; C086631:mineral trioxide aggregate; D014867:Water; D001729:Bismuth