The Experts below are selected from a list of 2064 Experts worldwide ranked by ideXlab platform

F S Silva - One of the best experts on this subject based on the ideXlab platform.

  • microstructure hardness corrosion resistance and porcelain shear bond strength comparison between cast and hot pressed cocrmo alloy for metal ceramic Dental restorations
    Journal of The Mechanical Behavior of Biomedical Materials, 2012
    Co-Authors: Bruno Henriques, Delfim Soares, F S Silva
    Abstract:

    Abstract Objectives: The purpose of this study was to compare the microstructure, hardness, corrosion resistance and metal–porcelain bond strength of a CoCrMo Dental alloy obtained by two routes, cast and hot pressing. Methods: CoCrMo alloy substrates were obtained by casting and hot pressing. Substrates’ microstructure was examined by the means of Optical Microscopy (OM) and by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). Hardness tests were performed in a microhardness indenter. The electrochemical behavior of substrates was investigated through potentiodynamic tests in a saline solution (8g NaCl/L). Substrates were bonded to Dental porcelain and metal–porcelain bond strength was assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5 mm/min) until fracture. Fractured surfaces as well as undestroyed interface specimens were examined with Stereomicroscopy and SEM-EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The t-test ( p 0.05 ) was used to compare shear bond strength results. Results: Cast specimens exhibited dendritic microstructures whereas hot pressed specimens exhibited a typical globular microstructure with a second phase spread through the matrix. The hardness registered for hot pressed substrates was greater than that of cast specimens, 438±24HV/1 and 324±8HV/1, respectively. Hot pressed substrates showed better corrosion properties than cast ones, i.e. higher OCP; higher corrosion potential (E corr ) and lower current densities (i corr ). No significant difference was found ( p 0.05 ) in metal–ceramic bond strength between cast (116.5±6.9 MPa) and hot pressed (114.2±11.9 MPa) substrates. The failure type analysis revealed an adhesive failure for all specimens. Significance: Hot pressed products arise as an alternative to cast products in Dental Prosthetics, as they impart enhanced mechanical and electrochemical properties to prostheses without compromising the metal–ceramic bond strength.

Elsa Antunes - One of the best experts on this subject based on the ideXlab platform.

  • zirconia in Dental Prosthetics a literature review
    Journal of materials research and technology, 2019
    Co-Authors: Jonathan Grech, Elsa Antunes
    Abstract:

    A large portion of the global human population carries a type of medical implant. Dental implants are an important part of this category, and the crowns they support are vital for satisfying the patients' needs both functionally and aesthetically. Materials science pertaining to Dental crowns is a driver of their development, and currently zirconium oxide (zirconia) is a promising non-metal alternative, exhibiting biocompatibility and excellent mechanical and aesthetic properties. This review aims to collate a selection of the extensive testing and research that has been performed and evaluated on a variety of zirconia-based ceramics, as there are many commercial brands developing blank and powdered samples for refinement into structurally sound Dental Prosthetics. Significant advancements regarding manufacturing technologies for zirconia-based ceramics are also currently in progress. Methodologies and conditions for uniaxial and isostatic pressing of zirconia powder are reviewed, as are the benefits of emerging CAD/CAM technologies. Several knowledge gaps were identified based on this review, primarily that different sintering conditions and methodologies, such as two-step sintering, should be investigated experimentally. Preliminary studies using alternative methods show promising results, and further trialling would help to ensure that the mechanical, aesthetic and ageing properties of the final product are enhanced and optimised.

Bruno Henriques - One of the best experts on this subject based on the ideXlab platform.

  • microstructure hardness corrosion resistance and porcelain shear bond strength comparison between cast and hot pressed cocrmo alloy for metal ceramic Dental restorations
    Journal of The Mechanical Behavior of Biomedical Materials, 2012
    Co-Authors: Bruno Henriques, Delfim Soares, F S Silva
    Abstract:

    Abstract Objectives: The purpose of this study was to compare the microstructure, hardness, corrosion resistance and metal–porcelain bond strength of a CoCrMo Dental alloy obtained by two routes, cast and hot pressing. Methods: CoCrMo alloy substrates were obtained by casting and hot pressing. Substrates’ microstructure was examined by the means of Optical Microscopy (OM) and by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). Hardness tests were performed in a microhardness indenter. The electrochemical behavior of substrates was investigated through potentiodynamic tests in a saline solution (8g NaCl/L). Substrates were bonded to Dental porcelain and metal–porcelain bond strength was assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5 mm/min) until fracture. Fractured surfaces as well as undestroyed interface specimens were examined with Stereomicroscopy and SEM-EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The t-test ( p 0.05 ) was used to compare shear bond strength results. Results: Cast specimens exhibited dendritic microstructures whereas hot pressed specimens exhibited a typical globular microstructure with a second phase spread through the matrix. The hardness registered for hot pressed substrates was greater than that of cast specimens, 438±24HV/1 and 324±8HV/1, respectively. Hot pressed substrates showed better corrosion properties than cast ones, i.e. higher OCP; higher corrosion potential (E corr ) and lower current densities (i corr ). No significant difference was found ( p 0.05 ) in metal–ceramic bond strength between cast (116.5±6.9 MPa) and hot pressed (114.2±11.9 MPa) substrates. The failure type analysis revealed an adhesive failure for all specimens. Significance: Hot pressed products arise as an alternative to cast products in Dental Prosthetics, as they impart enhanced mechanical and electrochemical properties to prostheses without compromising the metal–ceramic bond strength.

Jonathan Grech - One of the best experts on this subject based on the ideXlab platform.

  • zirconia in Dental Prosthetics a literature review
    Journal of materials research and technology, 2019
    Co-Authors: Jonathan Grech, Elsa Antunes
    Abstract:

    A large portion of the global human population carries a type of medical implant. Dental implants are an important part of this category, and the crowns they support are vital for satisfying the patients' needs both functionally and aesthetically. Materials science pertaining to Dental crowns is a driver of their development, and currently zirconium oxide (zirconia) is a promising non-metal alternative, exhibiting biocompatibility and excellent mechanical and aesthetic properties. This review aims to collate a selection of the extensive testing and research that has been performed and evaluated on a variety of zirconia-based ceramics, as there are many commercial brands developing blank and powdered samples for refinement into structurally sound Dental Prosthetics. Significant advancements regarding manufacturing technologies for zirconia-based ceramics are also currently in progress. Methodologies and conditions for uniaxial and isostatic pressing of zirconia powder are reviewed, as are the benefits of emerging CAD/CAM technologies. Several knowledge gaps were identified based on this review, primarily that different sintering conditions and methodologies, such as two-step sintering, should be investigated experimentally. Preliminary studies using alternative methods show promising results, and further trialling would help to ensure that the mechanical, aesthetic and ageing properties of the final product are enhanced and optimised.

Delfim Soares - One of the best experts on this subject based on the ideXlab platform.

  • microstructure hardness corrosion resistance and porcelain shear bond strength comparison between cast and hot pressed cocrmo alloy for metal ceramic Dental restorations
    Journal of The Mechanical Behavior of Biomedical Materials, 2012
    Co-Authors: Bruno Henriques, Delfim Soares, F S Silva
    Abstract:

    Abstract Objectives: The purpose of this study was to compare the microstructure, hardness, corrosion resistance and metal–porcelain bond strength of a CoCrMo Dental alloy obtained by two routes, cast and hot pressing. Methods: CoCrMo alloy substrates were obtained by casting and hot pressing. Substrates’ microstructure was examined by the means of Optical Microscopy (OM) and by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). Hardness tests were performed in a microhardness indenter. The electrochemical behavior of substrates was investigated through potentiodynamic tests in a saline solution (8g NaCl/L). Substrates were bonded to Dental porcelain and metal–porcelain bond strength was assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5 mm/min) until fracture. Fractured surfaces as well as undestroyed interface specimens were examined with Stereomicroscopy and SEM-EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The t-test ( p 0.05 ) was used to compare shear bond strength results. Results: Cast specimens exhibited dendritic microstructures whereas hot pressed specimens exhibited a typical globular microstructure with a second phase spread through the matrix. The hardness registered for hot pressed substrates was greater than that of cast specimens, 438±24HV/1 and 324±8HV/1, respectively. Hot pressed substrates showed better corrosion properties than cast ones, i.e. higher OCP; higher corrosion potential (E corr ) and lower current densities (i corr ). No significant difference was found ( p 0.05 ) in metal–ceramic bond strength between cast (116.5±6.9 MPa) and hot pressed (114.2±11.9 MPa) substrates. The failure type analysis revealed an adhesive failure for all specimens. Significance: Hot pressed products arise as an alternative to cast products in Dental Prosthetics, as they impart enhanced mechanical and electrochemical properties to prostheses without compromising the metal–ceramic bond strength.