title: Effect of ultrasonic excitation on the porosity of glass ionomer cement: a scanning electron microscope evaluation.
abstract: BACKGROUND
  Ultrasonic excitation (US) was applied to glass ionomer cement (GIC) during early set time to increase the advantageous properties of this material.
  
  
  OBJECTIVE
  The aim of this in vitro study was to assess the inner porosity of GIC after US.
  
  
  METHODS
  A total of 16 specimens, for each material, were prepared from high-viscosity GIC Fuji IX GP, Ketac Molar, and Ketac Molar Easymix. Half of these specimens (n = 8) received 30 s of US during the initial cement setting. After completion of the material setting, specimens were fractured and observed by scanning electronic microscopy to quantitatively assay porosity inside the material using Image J software.
  
  
  RESULTS
  Statistical data analysis revealed that US reduced the porosity for all tested materials (P ≤ 0.05). The following reductions (expressed in percentages) were achieved: Fuji IX--from 3.9% to 2.8%; Ketac Molar Easy Mix--from 4.4% to 2.6%, and Ketac Molar--from 2.4% to 1.6%.
  
  
  CONCLUSIONS
  Under the tested conditions, US was an effective method for porosity reduction inside the material.
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, Araraquara Dental School, São Paulo State University, Rua Humaitá, 14801-903 Araraquara, SP, Brazil. crcoldebella@yahoo.com.br
authors.forename: Cármen Regina
authors.initials: CR
authors.lastname: Coldebella
authors.forename: Lourdes
authors.initials: L
authors.lastname: Santos-Pinto
authors.forename: Angela Cristina Cilense
authors.initials: AC
authors.lastname: Zuanon
mesh_terms: D000818:Animals; D002417:Cattle; D003737:Dental Cavity Preparation / Q000295:instrumentation*; D003793:Dental Restoration, Permanent / Q000295:instrumentation*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000601:surgery; D016062:Porosity; D013499:Surface Properties; D014076:Tooth Diseases / Q000601:surgery*; D014465:Ultrasonics
chemical_list: D005899:Glass Ionomer Cements