title: The use of acoustic microscopy to study the mechanical properties of glass-ionomer cement.
abstract: OBJECTIVE
  The aim of the study was to investigate the relationship between microstructure, acoustic and mechanical properties of hardened dental cement samples, prepared with different powder/water ratios.
  
  
  METHODS
  Glass-ionomer dental cement samples, prepared with a standard amount of cement powder and different amounts of water have been examined after being hardened. Surface microstructure and ultrasound, longitudinal and shear velocities were obtained with a scanning acoustic microscope. Conditional effective elastic modulus and Poisson's ratio have been calculated using longitudinal and shear sound velocity values. Then on the same samples elastic modulus and microhardness have been determined by standard tests. Additional samples have been used to determine compressive strength.
  
  
  RESULTS
  Density; conditionally instantaneous elastic modulus; high-elasticity modulus and compression strength of the samples decrease when large amounts of water were used for their preparation. At the same time porosity and microhardness of the cement matrix increase. Acoustic parameters and parameters of elasticity, calculated on the basis of sound velocity, demonstrated changes, similar to those obtained in standard mechanical tests.
  
  
  CONCLUSIONS
  The established relation between microstructure, acoustic and mechanical parameters demonstrated a high capacity of acoustic microscopy application for non-destructive characterization of dental materials. A particular advantage of the acoustic microscopy is the opportunity to evaluate microstructure and mechanical properties on the same sample.
authors.affiliation: The Emanuel's Institute for BioChemical Physics of the Russian Academy of Science, 4, Kosygin Street, 119991 Moscow, Russia. isi@com2com.ru
authors.forename: L A
authors.initials: LA
authors.lastname: Denisova
authors.forename: R G
authors.initials: RG
authors.lastname: Maev
authors.forename: I Ya
authors.initials: IY
authors.lastname: Poyurovskaya
authors.forename: T V
authors.initials: TV
authors.lastname: Grineva
authors.forename: A F
authors.initials: AF
authors.lastname: Denisov
authors.forename: E Yu
authors.initials: EY
authors.lastname: Maeva
authors.forename: E Yu
authors.initials: EY
authors.lastname: Bakulin
mesh_terms: D019245:Compressive Strength; D004548:Elasticity; D005899:Glass Ionomer Cements / Q000737:chemistry; D006244:Hardness; D033401:Microscopy, Acoustic; D016062:Porosity
chemical_list: D005899:Glass Ionomer Cements