title: The effect of mixing method on tricalcium silicate-based cement.
abstract: OBJECTIVE
  To evaluate the effect of three methods of mixing on the physical and chemical properties of tricalcium silicate-based cements.
  
  
  METHODS
  The materials evaluated were MTA Angelus and Portland cement with 20% zirconium oxide (PC-20-Zr). The cements were mixed using a 3 : 1 powder-to-liquid ratio. The mixing methods were manual (m), trituration (tr) and ultrasonic (us) activation. The materials were characterized by means of scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy. Flowability was analysed according to ANSI/ADA 57/2012. Initial and final setting times were assessed following ASTM C266/08. Volume change was evaluated using a micro-CT volumetric method. Solubility was analysed according to ADA 57/2012. pH and calcium ion release were measured after 3, 24, 72 and 168 h. Statistical analysis was performed using two-way analysis of variance. The level of significance was set at P = 0.05.
  
  
  RESULTS
  The SEM analysis revealed that ultrasonic activation was associated with a homogeneous distribution of particles. Flowability, volume change and initial setting time were not influenced by the mixing method (P > 0.05). Solubility was influenced by the mixing method (P < 0.05). For pH, at 168 h, significant differences were found between MTA-m and PC-20-Zr-m (P < 0.05). For calcium ion release, PC-20-Zr-tr had higher values than MTA-m at 3 h, and MTA-tr had higher values than PC-20-Zr-m at 168 h (P < 0.05).
  
  
  CONCLUSIONS
  The ultrasonic and trituration methods led to higher calcium ion release and pH compared with manual mixing for all cements, whilst the ultrasonic method produced smaller particles for the PC-20-Zr cement. Flow, setting times and volume change were not influenced by the mixing method used; however, it did have an impact on solubility.
authors.affiliation: Department of Dentistry, Dental School of Bauru, University of São Paulo (USP), Bauru, SP, Brazil.
authors.forename: J A
authors.initials: JA
authors.lastname: Duque
authors.affiliation: Department of Dentistry, Dental School of Bauru, University of São Paulo (USP), Bauru, SP, Brazil.
authors.forename: S L
authors.initials: SL
authors.lastname: Fernandes
authors.affiliation: Department of Dentistry, Dental School of Bauru, University of São Paulo (USP), Bauru, SP, Brazil.
authors.forename: J P
authors.initials: JP
authors.lastname: Bubola
authors.affiliation: Department of Dentistry, Dental School of Bauru, University of São Paulo (USP), Bauru, SP, Brazil.
authors.forename: M A H
authors.identifier: http://orcid.org/0000-0003-3051-737X
authors.initials: MAH
authors.lastname: Duarte
authors.affiliation: Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Msida, Malta.
authors.forename: J
authors.initials: J
authors.lastname: Camilleri
authors.affiliation: Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: M A
authors.identifier: http://orcid.org/0000-0001-6244-2531
authors.initials: MA
authors.lastname: Marciano
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D055598:Chemical Phenomena; D003738:Dental Cements / Q000737:chemistry*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D017640:Silicates / Q000737:chemistry*; D012995:Solubility; D014465:Ultrasonics
chemical_list: D017610:Calcium Compounds; D003738:Dental Cements; D017640:Silicates; C506393:tricalcium silicate
keywords: mixing methods; scanning electron microscopy; solubility; tricalcium silicate