title: Calcium silicate-based sealers: Assessment of physicochemical properties, porosity and hydration.
abstract: OBJECTIVE
  Investigation of hydration, chemical, physical properties and porosity of experimental calcium silicate-based sealers.
  
  
  METHODS
  Experimental calcium silicate-based sealers with calcium tungstate and zirconium oxide radio-opacifiers were prepared by mixing 1g of powder to 0.3 mL of 80% distilled water and 20% propylene glycol. MTA and MTA Fillapex were used as controls. The raw materials and set sealers were characterized using a combination of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Physical properties were analyzed according to ANSI/ADA. The pH and calcium ion release were assessed after 3, 24, 72 and 168 h. The porosity was assessed using mercury intrusion porosimetry.
  
  
  RESULTS
  The analysis of hydration of prototype sealers revealed calcium hydroxide as a by-product resulting in alkaline pH and detection of calcium ion release, with high values in initial periods. The radiopacity was similar to MTA for the sealers containing high amounts of radio-opacifiers (p>0.05). Flowability was higher and film thickness was lower for resinous MTA Fillapex sealer (p<0.05). The test sealers showed water sorption and porosity similar to MTA (p>0.05).
  
  
  CONCLUSIONS
  The prototype sealers presented adequate hydration, elevated pH and calcium ion release. Regarding physical properties, elevated proportions of radio-opacifiers were necessary to accomplish adequate radiopacity, enhance flowability and reduce film thickness. All the tested sealers presented water sorption and porosity similar to MTA.
authors.affiliation: Department of Dentistry, Dental School of Bauru, University of São Paulo - USP, Bauru, SP, Brazil.
authors.forename: Marina Angélica
authors.initials: MA
authors.lastname: Marciano
authors.affiliation: Department of Dentistry, Dental School of Bauru, University of São Paulo - USP, Bauru, SP, Brazil. Electronic address: mhungaro@fob.usp.br.
authors.forename: Marco Antonio Hungaro
authors.initials: MA
authors.lastname: Duarte
authors.affiliation: Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta.
authors.forename: Josette
authors.initials: J
authors.lastname: Camilleri
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D016062:Porosity; D012387:Root Canal Filling Materials / Q000138:chemical synthesis / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D017973:Tungsten Compounds / Q000737:chemistry; D014961:X-Ray Diffraction; D015040:Zirconium / Q000737:chemistry
chemical_list: D017610:Calcium Compounds; D012387:Root Canal Filling Materials; D017640:Silicates; D017973:Tungsten Compounds; C018858:calcium tungstate; D015040:Zirconium; C028541:zirconium oxide; C031293:calcium silicate
keywords: Hydration; Material characterization; Physical properties; Porosity; Root canal sealers; Scanning electron microscopy; Tricalcium silicate