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Biomedical Engineering and Bioengineering Commons™
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Full-Text Articles in Biomedical Engineering and Bioengineering
Heat-Treatment Behavior Of High-Palladium Dental Alloys, Qiang Wu, William A. Brantley, John C. Mitchell, Stanley G. Vermilyea, Jianzhong Xiao, Wenhua Guo
Heat-Treatment Behavior Of High-Palladium Dental Alloys, Qiang Wu, William A. Brantley, John C. Mitchell, Stanley G. Vermilyea, Jianzhong Xiao, Wenhua Guo
Cells and Materials
Four high-palladium dental alloys were cast, quenched following solidification, and heat treated at temperatures ranging from 200° to 1,800°F. The Vickers hardness of each alloy was measured, and microstructural changes were studied by scanning electron microscopy (SEM). Phase transformations were investigated by thermomechanical analysis (TMA). Heat treatment at 1,600° and 1,800°F significantly decreased the hardness of one Pd-Cu-Ga alloy, compared to the as-cast condition, as did heat treatment at 1,800°F for the other Pd-Cu-Ga alloy and one Pd-Ga alloy, and yielded fine-grained microstructures of the palladium solid solution. There were generally no significant changes in the hardness of the other …
Alloy Oxidation And Porcelain Fused To Alloy Interaction In Noble Alloy Systems, M. S. Bapna, H. J. Mueller
Alloy Oxidation And Porcelain Fused To Alloy Interaction In Noble Alloy Systems, M. S. Bapna, H. J. Mueller
Cells and Materials
The oxidation and porcelain fusion characteristics of noble alloys containing a variety of minor oxidizable elements, including Cu, Sn, In, Ga, Mn, and Fe were investigated. Four porcelain alloys systems: a Pd-base alloy (Naturelle}, two Pd-Ag-based alloys (Jelstar and Acclaim}, and a high Au-alloy (SMG-3) were examined by scanning electron microscopy and energy dispersive spectroscopy after being heat treated and after being fused with porcelain. Internal oxidation of minor alloying elements occurred within several micrometers from the surface in all four alloys. Surface nodules as detected by other investigators for a Pd-Ag alloy were also detected in this study. Evidence …
Ultrastructural Observations Of Peri-Implant Mucosa Morphology Around Different Types Of Abutment In Humans, C. Piacentini, P. Lanzarini, R. Rodriguez Y Baena, S. Rizzo, C. Brusotti
Ultrastructural Observations Of Peri-Implant Mucosa Morphology Around Different Types Of Abutment In Humans, C. Piacentini, P. Lanzarini, R. Rodriguez Y Baena, S. Rizzo, C. Brusotti
Cells and Materials
Scanning electron microscopy (SFM) and transmission electron microscopy (TEM) were used to examine the morphological aspects of peri-implant mucosa around abutments of differing geometry (biconical and cylindrical) and of differing surface micromorphology. The samples were taken from seven patients who had undergone implant surgery at least one year prior to the study. In samples from biconical abutments, SEM of the sulcular epithelium showed that it consisted of flattened polygonal cells with a surface resembling a honeycomb. Superficial desquamation was rarely found. In contrast, in the samples from cylindrical abutments, the sulcular epithelium showed extensive desquamation and surface irregularity, but not …
Mechanism For Formation Of Lamellar Constituents In Grain-Refined Pd-Cu-Ga Dental Alloys, William A. Brantley, Zhuo Cai, John C. Mitchell, Stanley G. Vermilyea
Mechanism For Formation Of Lamellar Constituents In Grain-Refined Pd-Cu-Ga Dental Alloys, William A. Brantley, Zhuo Cai, John C. Mitchell, Stanley G. Vermilyea
Cells and Materials
Grain-refined Pd-Cu-Ga dental alloys solidify with a lamellar microstructural constituent that affects a variety of clinically relevant properties. While formation of this constituent has been attributed to eutectic solidification, an alternative mechanism of discontinuous precipitation has been proposed. Using a representative grain-refined Pd-Cu-Ga dental alloy, casting procedures involving two different rates of solidification were used: (a) A standard thin-walled coping configuration for a metal-ceramic restoration was cast into a room temperature mold, followed by rapid quenching into an ice-water mixture. (b) A thin plate specimen was cast into a standard elevated-temperature mold, with the same subsequent rapid quenching procedure. Neither …