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1. Impact of Morphology and Microstructure on the Mechanical Properties of Ge-As-Pb-Se Glass Ceramics

Author

Rashi Sharma, Rebecca S. Welch, Myungkoo Kang, Claudia Goncalves, Cesar Blanco, Andy Buff, Vincent Fauvel, Thomas Loretz, Clara Rivero-Baleine, and Kathleen Richardson

Subjects
chalcogenide glasses, mechanical properties, glass-ceramic, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, QD1-999
Abstract

The impact of base glass morphology and post heat-treatment protocol on the mechanical properties (Vickers hardness and Young’s modulus) of a multi-component glass-ceramic was examined. Two parent chalcogenide glasses with identical composition but varying morphology (homogeneous and phase separated) were evaluated for their mechanical properties following identical thermal processing to induce crystallization. The nucleation and growth rates of the starting materials were compared for the two glasses, and the resulting crystal phases and phase fractions formed through heat treatment were quantified and related to measured mechanical properties of the glass ceramics. The presence of a Pb-rich amorphous phase with a higher crystal formation tendency in the phase-separated parent glass significantly impacted the volume fraction of the crystal phases formed after heat-treatment. Pb-rich cubic crystal phases were found to be dominant in the resulting glass ceramic, yielding a minor enhancement of the material’s mechanical properties. This was found to be less than a more moderate enhancement of mechanical properties due to the formation of the dominant needle-like As2Se3 crystallites resulting from heat treatment of the homogeneous, commercially melted parent glass. The greater enhancement of both Vickers hardness and modulus in this glass ceramic attributable to the high-volume fraction of anisotropic As2Se3 crystallites in the post heat-treated commercial melt highlights the important role base glass morphology can play on post heat-treatment microstructure.

Published
2020
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2. An evaluation of the biocompatibility and osseointegration of novel glass fiber reinforced composite implants: In vitro and in vivo studies

Author

Wei Zhen Lew, Emily Lu, Thomas Loretz, Che Tong Lin, Lu Luke, Ya Hui Chan, and Sheng Wei Feng

Subjects
Male, Materials science, Biocompatibility, Surface Properties, Glass fiber, Biocompatible Materials, 02 engineering and technology, Cell morphology, Composite Resins, Osseointegration, law.invention, 03 medical and health sciences, Dental Materials, 0302 clinical medicine, Implants, Experimental, In vivo, law, Materials Testing, Alloys, Animals, Humans, General Materials Science, Femur, Bone regeneration, General Dentistry, Cell Proliferation, Dental Implants, Titanium, Osteoblasts, Cell Differentiation, 030206 dentistry, Epoxy, 021001 nanoscience & nanotechnology, Dental Prosthesis Design, Mechanics of Materials, visual_art, Bioactive glass, visual_art.visual_art_medium, Microscopy, Electron, Scanning, Wettability, Glass, Rabbits, 0210 nano-technology, Biomedical engineering
Abstract

Objectives The aim of this study was to evaluate the in vitro biocompatibility and in vivo osseointegration of three novel bioactive glass fiber reinforced composite (GFRC) implants and to compare these with metal (Ti6Al4V) implants. Methods The surfaces of these experimental substrates were characterized by scanning electron microscopy (SEM), a 2D profilometer and by contact angle measurement. In vitro biological performance was assessed using MG-63 human osteoblast-like cell morphology, cell proliferation assays and the alkaline phosphatase (ALP) activity testing. Furthermore, in vivo osseointegration performance was examined by installing samples into rabbit femurs and evaluated the results using micro-CT, histology and histomorphometrical analysis; these assessments were carried out after 1, 2, 4 and 8 weeks of healing. Results The results showed that moderate surface roughness, moderate hydrophilic exposure and moderate homogenous exposure of bioactive glass fibers were present for all of the GFRC substrates. Furthermore, MG-63 cells, when cultured on all of the GFRC substrates, grew well and exhibited a more differentiated phenotype than cells grown on titanium alloy (Ti6Al4V) substrate. Histological evaluation revealed more newly-formed bone regeneration within the thread of the GFRC implants during the initial healing period. In addition, the novel GFRC implants with a bioactive Bio-fiber structure and glass particles within the epoxy resin matrix showed better bone volume/tissue volume (BV/TV) values at 4 weeks and this was accompanied by bone-implant contact (BIC) values at 8 weeks comparable to the Ti6Al4V group. Significance These findings demonstrated that novel GFRC implants seem to show improved osteogenesis and osseointegration functionality and have potential as a substitute for Ti6Al4V, or other metal-based materials, when used for clinically dental and orthopedic applications.

Published
2017

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