title: The effect of slurry preparation methods on biaxial flexural strength of dental porcelain.
abstract: BACKGROUND
  One-step and incremental mixing procedures are currently used to produce dental ceramic pastes. In the ceramic industry, high quality is obtained using one-step mixing, but in dentistry, the best method has not been yet determined.
  
  
  OBJECTIVE
  The purpose of this study is to evaluate the effects of 2 mixing techniques on the biaxial flexural strength and microstructure of dental porcelain.
  
  
  METHODS
  Feldspathic porcelain discs (2 × 15 mm in diameter) were produced and divided according to the ceramic paste preparation method, powder-liquid incremental mixing group (n=50) or one-step mixing, as a control group (n=50). Specimens were tested for biaxial flexural strength and characterized using porosimetry, relative humidity, SEM/EDS, XRD, and FT-IR analyses. Statistical analysis was conducted using Weibull statistics. The Weibull modulus, characteristic strength and relative humidity were compared between groups, using Student's t-test and Mann-Whitney U test (α=.05).
  
  
  RESULTS
  The powder-liquid incremental mixing group showed significantly higher values (SD) of Weibull modulus (6.74 (0.70), P<.001) and characteristic strength (79.87 (2.01) MPa, P<.001) when compared to the one-step mixing group (4.94 (0.94) and 75.95 (2.61) MPa). Significantly lower mean (SD) relative humidity values (P=.009) were found for powder-liquid incremental mixing group (20% (0.5%)) compared to one-step mixing group (22% (1%)). XRD spectra showed that the one-step mixing group produced higher amounts of the amorphous phase.
  
  
  CONCLUSIONS
  Specimens produced by the incremental mixing technique showed higher biaxial flexural strength than one-step mixing.
authors.affiliation: PhD student. Institute of Biomedical Engineering (INEB - Instituto de Engenharia Biomédica) and Faculty of Engineering. University of Porto (FEUP, Universidade do Porto), Portugal.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Pelaez-Vargas
authors.forename: Jaime A
authors.initials: JA
authors.lastname: Dussan
authors.forename: Luis F
authors.initials: LF
authors.lastname: Restrepo-Tamayo
authors.forename: Carlos
authors.initials: C
authors.lastname: Paucar
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Ferreira
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Monteiro
mesh_terms: D045424:Complex Mixtures / Q000737:chemistry; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D003801:Dental Veneers; D008422:Materials Testing; D018583:Pliability
chemical_list: D045424:Complex Mixtures; D003776:Dental Porcelain