title: Influence of powder/liquid ratio on the radiodensity and diametral tensile strength of glass ionomer cements.
abstract: Clinicians tend to make reductions in glass ionomer power/liquid (P/L) ratios since some materials are difficult to mix and flow into small cavities, grooves or pits. In general, changing the P/L ratio decreases the physical and mechanical properties of conventional glass ionomer cements (GICs) and resin modified glass ionomer cements (RMGICs), but alterations seem to depend on their composition.
  
  
  OBJECTIVE
  To determine the influence of P/L ratio on the radiodensity and diametral tensile strength (DTS) of glass ionomer cements.
  
  
  METHODS
  There were 2 factors under study: P/L ratio (manufacturer's recommended P/L ratio and a 50% reduced P/L ratio), and materials (Vitro Molar, Vitro Fil, Vitro Cem conventional GICs and Vitro Fil LC, Ortho Glass LC RMGICs. Five 1-mm-thick samples of each material-P/L ratio were produced for radiodensity evaluation. Samples were x-ray exposed onto Digora phosphor plate and radiodensity was obtained using the software Digora for Windows 2.5 Rev 0. For DTS, five (4.0 x 8.0 mm) cylinder samples of each material were tested (0.5 mm/min). Data were subjected to one- and two-way ANOVA (5x2) followed by Tukey's HSD test, or Kruskal-Wallis and Dunn's method. For paired comparisons, t-test or Mann-Whitney test were used (α=0.05).
  
  
  RESULTS
  There was a significant interaction (P=0.001) for the studied factors (materials vs. P/L ratio). Reduced P/L ratio resulted in significantly lower DTS for the RMGICs, but radiodensity was affected for all materials (P<0.05).
  
  
  CONCLUSIONS
  Reduced P/L ratio affected properties of the tested glass ionomer cements. RMGICs were more susceptible to lower values of DTS, but radiodensity decreased for all materials following P/L ratio reduction.
authors.affiliation: Federal University of Goiás, Dental School, Restorative Dentistry Area, Goiânia, GO, Brazil. rbfonseca.ufg@gmail.com
authors.forename: Rodrigo Borges
authors.initials: RB
authors.lastname: Fonseca
authors.forename: Carolina Assaf
authors.initials: CA
authors.lastname: Branco
authors.forename: Paulo Sérgio
authors.initials: PS
authors.lastname: Quagliatto
authors.forename: Luciano de Souza
authors.initials: Lde S
authors.lastname: Gonçalves
authors.forename: Carlos José
authors.initials: CJ
authors.lastname: Soares
authors.forename: Hugo Lemes
authors.initials: HL
authors.lastname: Carlo
authors.forename: Lourenço
authors.initials: L
authors.lastname: Correr-Sobrinho
mesh_terms: D000704:Analysis of Variance; D005899:Glass Ionomer Cements / Q000737:chemistry*; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D011208:Powders / Q000737:chemistry; D011856:Radiographic Image Enhancement; D018709:Statistics, Nonparametric; D013718:Tensile Strength; D013997:Time Factors
chemical_list: D005899:Glass Ionomer Cements; D011208:Powders