The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform

Yu Zhang - One of the best experts on this subject based on the ideXlab platform.

  • using glass graded zirconia to increase delamination growth resistance in porcelain zirconia dental structures
    Dental Materials, 2018
    Co-Authors: Herzl Chai, Adam J Mieleszko, Yu Zhang
    Abstract:

    Abstract Objective Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their tendency to delaminate along the P/Z interface remains a practical problem so that assessing and improving the interfacial strength are important design aspects. This work examines the effect of modifying the zirconia veneering surface with an in-house felspathic glass on the interfacial fracture resistance of fused P/Z. Methods Three material systems are studied: porcelain fused to zirconia (control) and porcelain fused to glass-graded zirconia with and without the presence of a glass interlayer. The specimens were loaded in a four-point-bend fixture with the porcelain veneer in tension. The evolution of damage is followed with the aid of a video camera. The interfacial fracture energy GC was determined with the aid of a FEA, taking into account the stress shielding effects due to the presence of adjacent channel cracks. Results Similarly to a previous study on PFZ specimens, the fracture sequence consisted of unstable growth of channel cracks in the veneer followed by stable cracking along the P/Z interface. However, the value of GC for the graded zirconia was approximately 3 times that of the control zirconia, which is due to the good adhesion between porcelain and the glass network structure on the zirconia surface. Significance Combined with its improved bonding to resin-based cements, increased resistance to surface damage and good Esthetic Quality, graded zirconia emerges as a viable material concept for dental restorations.

  • on the interfacial fracture of porcelain zirconia and graded zirconia dental structures
    Acta Biomaterialia, 2014
    Co-Authors: Herzl Chai, Adam J Mieleszko, Yu Zhang
    Abstract:

    Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their susceptibility to fracture remains a practical problem. The failure of PFZ prostheses often involves crack initiation and growth in the porcelain, which may be followed by fracture along the porcelain/zirconia (P/Z) interface. In this work, we characterized the process of fracture in two PFZ systems, as well as a newly developed graded glass-zirconia structure with emphases placed on resistance to interfacial cracking. Thin porcelain layers were fused onto Y-TZP plates with or without the presence of a glass binder. The specimens were loaded in a four-point-bending fixture with the thin porcelain veneer in tension, simulating the lower portion of the connectors and marginal areas of a fixed dental prosthesis (FDP) during occlusal loading. The evolution of damage was observed by a video camera. The fracture was characterized by unstable growth of cracks perpendicular to the P/Z interface (channel cracks) in the porcelain layer, which was followed by stable cracking along the P/Z interface. The interfacial fracture energy GC was determined by a finite-element analysis taking into account stress-shielding effects due to the presence of adjacent channel cracks. The resulting GC was considerably less than commonly reported values for similar systems. Fracture in the graded Y-TZP samples occurred via a single channel crack at a much greater stress than for PFZ. No delamination between the residual glass layer and graded zirconia occurred in any of the tests. Combined with its enhanced resistance to edge chipping and good Esthetic Quality, graded Y-TZP emerges as a viable material concept for dental restorations.

  • chipping resistance of graded zirconia ceramics for dental crowns
    Journal of Dental Research, 2012
    Co-Authors: Yu Zhang, Herzl Chai, James J W Lee, Brian R Lawn
    Abstract:

    A serious drawback of veneering porcelains is a pronounced susceptibility to chipping. Glass-infiltrated dense zirconia structures can now be produced with Esthetic Quality, making them an attractive alternative. In this study, we examined the hypothesis that such infiltrated structures are much more chip-resistant than conventional porcelains, and at least as chip-resistant as non-infiltrated zirconia. A sharp indenter was used to produce chips in flat and anatomically correct glass-infiltrated zirconia crown materials, and critical loads were measured as a function of distance from the specimen edge (flat) or side wall (crown). Control data were obtained on zirconia specimens without infiltration and on crowns veneered with porcelains. The results confirmed that the resistance to chipping in graded zirconia is more than 4 times higher than that of porcelain-veneered zirconia and is at least as high as that of non-veneered zirconia.

Herzl Chai - One of the best experts on this subject based on the ideXlab platform.

  • using glass graded zirconia to increase delamination growth resistance in porcelain zirconia dental structures
    Dental Materials, 2018
    Co-Authors: Herzl Chai, Adam J Mieleszko, Yu Zhang
    Abstract:

    Abstract Objective Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their tendency to delaminate along the P/Z interface remains a practical problem so that assessing and improving the interfacial strength are important design aspects. This work examines the effect of modifying the zirconia veneering surface with an in-house felspathic glass on the interfacial fracture resistance of fused P/Z. Methods Three material systems are studied: porcelain fused to zirconia (control) and porcelain fused to glass-graded zirconia with and without the presence of a glass interlayer. The specimens were loaded in a four-point-bend fixture with the porcelain veneer in tension. The evolution of damage is followed with the aid of a video camera. The interfacial fracture energy GC was determined with the aid of a FEA, taking into account the stress shielding effects due to the presence of adjacent channel cracks. Results Similarly to a previous study on PFZ specimens, the fracture sequence consisted of unstable growth of channel cracks in the veneer followed by stable cracking along the P/Z interface. However, the value of GC for the graded zirconia was approximately 3 times that of the control zirconia, which is due to the good adhesion between porcelain and the glass network structure on the zirconia surface. Significance Combined with its improved bonding to resin-based cements, increased resistance to surface damage and good Esthetic Quality, graded zirconia emerges as a viable material concept for dental restorations.

  • on the interfacial fracture of porcelain zirconia and graded zirconia dental structures
    Acta Biomaterialia, 2014
    Co-Authors: Herzl Chai, Adam J Mieleszko, Yu Zhang
    Abstract:

    Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their susceptibility to fracture remains a practical problem. The failure of PFZ prostheses often involves crack initiation and growth in the porcelain, which may be followed by fracture along the porcelain/zirconia (P/Z) interface. In this work, we characterized the process of fracture in two PFZ systems, as well as a newly developed graded glass-zirconia structure with emphases placed on resistance to interfacial cracking. Thin porcelain layers were fused onto Y-TZP plates with or without the presence of a glass binder. The specimens were loaded in a four-point-bending fixture with the thin porcelain veneer in tension, simulating the lower portion of the connectors and marginal areas of a fixed dental prosthesis (FDP) during occlusal loading. The evolution of damage was observed by a video camera. The fracture was characterized by unstable growth of cracks perpendicular to the P/Z interface (channel cracks) in the porcelain layer, which was followed by stable cracking along the P/Z interface. The interfacial fracture energy GC was determined by a finite-element analysis taking into account stress-shielding effects due to the presence of adjacent channel cracks. The resulting GC was considerably less than commonly reported values for similar systems. Fracture in the graded Y-TZP samples occurred via a single channel crack at a much greater stress than for PFZ. No delamination between the residual glass layer and graded zirconia occurred in any of the tests. Combined with its enhanced resistance to edge chipping and good Esthetic Quality, graded Y-TZP emerges as a viable material concept for dental restorations.

  • chipping resistance of graded zirconia ceramics for dental crowns
    Journal of Dental Research, 2012
    Co-Authors: Yu Zhang, Herzl Chai, James J W Lee, Brian R Lawn
    Abstract:

    A serious drawback of veneering porcelains is a pronounced susceptibility to chipping. Glass-infiltrated dense zirconia structures can now be produced with Esthetic Quality, making them an attractive alternative. In this study, we examined the hypothesis that such infiltrated structures are much more chip-resistant than conventional porcelains, and at least as chip-resistant as non-infiltrated zirconia. A sharp indenter was used to produce chips in flat and anatomically correct glass-infiltrated zirconia crown materials, and critical loads were measured as a function of distance from the specimen edge (flat) or side wall (crown). Control data were obtained on zirconia specimens without infiltration and on crowns veneered with porcelains. The results confirmed that the resistance to chipping in graded zirconia is more than 4 times higher than that of porcelain-veneered zirconia and is at least as high as that of non-veneered zirconia.

Adam J Mieleszko - One of the best experts on this subject based on the ideXlab platform.

  • using glass graded zirconia to increase delamination growth resistance in porcelain zirconia dental structures
    Dental Materials, 2018
    Co-Authors: Herzl Chai, Adam J Mieleszko, Yu Zhang
    Abstract:

    Abstract Objective Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their tendency to delaminate along the P/Z interface remains a practical problem so that assessing and improving the interfacial strength are important design aspects. This work examines the effect of modifying the zirconia veneering surface with an in-house felspathic glass on the interfacial fracture resistance of fused P/Z. Methods Three material systems are studied: porcelain fused to zirconia (control) and porcelain fused to glass-graded zirconia with and without the presence of a glass interlayer. The specimens were loaded in a four-point-bend fixture with the porcelain veneer in tension. The evolution of damage is followed with the aid of a video camera. The interfacial fracture energy GC was determined with the aid of a FEA, taking into account the stress shielding effects due to the presence of adjacent channel cracks. Results Similarly to a previous study on PFZ specimens, the fracture sequence consisted of unstable growth of channel cracks in the veneer followed by stable cracking along the P/Z interface. However, the value of GC for the graded zirconia was approximately 3 times that of the control zirconia, which is due to the good adhesion between porcelain and the glass network structure on the zirconia surface. Significance Combined with its improved bonding to resin-based cements, increased resistance to surface damage and good Esthetic Quality, graded zirconia emerges as a viable material concept for dental restorations.

  • on the interfacial fracture of porcelain zirconia and graded zirconia dental structures
    Acta Biomaterialia, 2014
    Co-Authors: Herzl Chai, Adam J Mieleszko, Yu Zhang
    Abstract:

    Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their susceptibility to fracture remains a practical problem. The failure of PFZ prostheses often involves crack initiation and growth in the porcelain, which may be followed by fracture along the porcelain/zirconia (P/Z) interface. In this work, we characterized the process of fracture in two PFZ systems, as well as a newly developed graded glass-zirconia structure with emphases placed on resistance to interfacial cracking. Thin porcelain layers were fused onto Y-TZP plates with or without the presence of a glass binder. The specimens were loaded in a four-point-bending fixture with the thin porcelain veneer in tension, simulating the lower portion of the connectors and marginal areas of a fixed dental prosthesis (FDP) during occlusal loading. The evolution of damage was observed by a video camera. The fracture was characterized by unstable growth of cracks perpendicular to the P/Z interface (channel cracks) in the porcelain layer, which was followed by stable cracking along the P/Z interface. The interfacial fracture energy GC was determined by a finite-element analysis taking into account stress-shielding effects due to the presence of adjacent channel cracks. The resulting GC was considerably less than commonly reported values for similar systems. Fracture in the graded Y-TZP samples occurred via a single channel crack at a much greater stress than for PFZ. No delamination between the residual glass layer and graded zirconia occurred in any of the tests. Combined with its enhanced resistance to edge chipping and good Esthetic Quality, graded Y-TZP emerges as a viable material concept for dental restorations.

Vincent Guérin - One of the best experts on this subject based on the ideXlab platform.

  • VISUAL CHARACTERIZATION OF THE Esthetic Quality OF THE ROSEBUSH
    Journal of Sensory Studies, 2009
    Co-Authors: Rachid Boumaza, Sabine Demotes-mainard, Lydie Huché-thélier, Vincent Guérin
    Abstract:

    Since its introduction into the analysis of foodstuffs, sensory analysis has been applied in several contexts. This work seeks to widen the field of sensory analysis to include ornamental plants and to characterize their Esthetic Quality. Using the rosebush as a plant model, an attribute generation protocol is proposed in order to develop a conventional profile of such products. Further to statistical treatments aiming to verify the unambiguity, discrimination and independence of these attributes, a reduced list of 18 attributes has been set up. These attributes make up the very core of the conventional profiling studies currently undertaken.

Qinghua Huang - One of the best experts on this subject based on the ideXlab platform.

  • Image Esthetic assessment using both hand-crafting and semantic features
    Neurocomputing, 2014
    Co-Authors: Lihua Guo, Yangchao Xiong, Qinghua Huang
    Abstract:

    Automatically assessing the visual Esthetics of images is of great interest in high-level vision research and has drawn much attention in recent years. Traditional methods heavily depend on the performance of subject region extraction. This paper proposes to use semantic features in the Esthetic assessment system because they can implicitly represent the image topic and be helpful if the subject region extraction fails. Accordingly, a framework combining the hand-crafting features with semantic features is proposed to evaluate image Esthetic Quality. The experimental results show that the semantic features can improve the performance of image Esthetic assessment.