feldspar and soda-lime

To determine how the variability in biaxial flexure strength of a soda-lime glass analogue for a PLV and DBC material was influenced by precementation operative variables and following resin-cement coating.. The flexural modulus of a transparent soda-lime glass was determined by longitudinally sectioning into rectangular bar-shaped specimens and the flexural moduli of three resin-based materials (Venus Flow, Rely-X Veneer and Clearfil Majesty Posterior) was also determined. Disc shaped soda-lime glass specimens (n=240) were divided into ten groups and were alumina particle air abraded, hydrofluoric (HF) acid-etched and resin-cement coated prior to biaxial flexure strength testing. Sample sets were profilometrically evaluated to determine the surface texture. One-way analyses of variance (ANOVA) and post hoc all paired Tukey tests were performed at a significance level of P<0.05. The mean biaxial flexure strengths were plotted against resin-coating thickness and a regression analysis enabled estimation of the 'actual' magnitude of strengthening.. The mean three-point flexural modulus of the soda-lime glass was 40.0 (1.0)GPa and the Venus Flow, Rely-X Veneer and Clearfil Majesty Posterior were 3.0 (0.2)GPa, 6.0 (0.2)GPa and 14.8 (1.6)GPa, respectively. At a theoretical 'zero' resin-coating thickness an increase in biaxial flexure strength of 20.1% (63.2MPa), 30.8% (68.8MPa) and 36.3% (71.7MPa), respectively was evident compared with the control (52.6 (5.5)MPa).. Disc-shaped specimens cut from round stock facilitated rapid fabrication of discs with uniform surface condition and demonstrated strength dependence was influenced by precementation parameters and resin-cementation variables.

Topics: Acid Etching, Dental; Algorithms; Aluminum Oxide; Aluminum Silicates; Calcium Compounds; Cementation; Ceramics; Coated Materials, Biocompatible; Composite Resins; Crowns; Dental Etching; Dental Materials; Dental Porcelain; Dental Veneers; Dentin-Bonding Agents; Elastic Modulus; Glass; Humans; Hydrofluoric Acid; Materials Testing; Oxides; Pliability; Potassium Compounds; Resin Cements; Sodium Hydroxide; Stress, Mechanical; Surface Properties

Porcelains with leucite crystals dispersed into various glass matrices were prepared for investigating the effects of the leucite crystals on the mechanical strength of glassy porcelain. The strength of glassy porcelains containing leucite crystals was affected by the differences of thermal expansion coefficients, compositions and deformation temperatures of the glass matrices. In the case of a large mismatch of thermal expansion between the leucite crystals and boro-silicate glass, the strength decreased with increasing amount of leucite. In leucite porcelains using a feldspar glass matrix, there was little or no effect of leucite on the strength. However, the strength of porcelains consisting of leucite crystals and a soda-lime glass matrix was enhanced with increasing leucite content, compared with that of the glassy matrix alone. Such an increase in strength is considered to be because the interface between the glassy matrix and leucite particles occurred in continuous phases, with an effect due to fusion occurring during the transition from leucite particles to the glass phase.

Topics: Aluminum Silicates; Boron Compounds; Calcium Compounds; Dental Porcelain; Glass; Hardness; Materials Testing; Microscopy, Electron, Scanning; Oxides; Pliability; Potassium Compounds; Silicates; Sodium Hydroxide; Surface Properties; Tensile Strength; Thermodynamics; X-Ray Diffraction