Bio-Medical Materials and Engineering - Volume 8, issue 1

Authors: Wang, Xiaodu | Mabrey, Jay D. | Agrawal, C. Mauli

Article Type: Research Article

Abstract: The purpose of this study was to investigate whether bone fracture properties change with species (humans, baboon, canine, bovine, and rabbit). A single‐layer compact sandwich (SCS) specimen and fractography were employed to evaluate bone fracture properties. In conjunction with measurements of the density and volume fractions of the mineral and organic phases, bone microstructure were also investigated. The results of this study indicate that bone fracture properties vary considerably with species. These differences are most likely due to variations in microstructural and compositional properties of bone (mineral and collagen) between the species. Baboon bone exhibited most similar fracture, microstructural, and …compositional properties compared to humans. However, significant differences were found in bone fracture properties between humans and the other three animal species. These differences were reflected either in bone microstructures or compositional properties. This interspecies comparison facilitates a better understanding of animal models and suitable use of the animal models in future bone fracture studies. Show more

Keywords: Bone, interspecies, fracture toughness, fracture surfaces, bone microstructures

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 1, pp. 1-9, 1998

Authors: Wang, Xiaodu | Mabrey, Jay D. | Agrawal, C. Mauli

Article Type: Research Article

Abstract: The purpose of this study was to investigate whether bone fracture properties change with species (humans, baboon, canine, bovine, and rabbit). A single‐layer compact sandwich (SCS) specimen and fractography were employed to evaluate bone fracture properties. In conjunction with measurements of the density and volume fractions of the mineral and organic phases, bone microstructure were also investigated. The results of this study indicate that bone fracture properties vary considerably with species. These differences are most likely due to variations in microstructural and compositional properties of bone (mineral and collagen) between the species. Baboon bone exhibited most similar fracture, microstructural, and …compositional properties compared to humans. However, significant differences were found in bone fracture properties between humans and the other three animal species. These differences were reflected either in bone microstructures or compositional properties. This interspecies comparison facilitates a better understanding of animal models and suitable use of the animal models in future bone fracture studies. Show more

Keywords: Bone, interspecies, fracture toughness, fracture surfaces, bone microstructures

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 1, pp. 1-9, 1998

Authors: Lewis, Gladius | Jonathan, Vinod | Kambhampati, Sarma

Article Type: Research Article

Abstract: The present study sought to examine if, and to what extent, the representation of the elastic properties of material(s) in a model of an endoprosthesis per se or a construct that includes an endoprosthesis affects the stresses in the model, when the finite element analysis method is used to obtain these stresses. For this purpose, two models were examined. One was of an elastomeric metacarpophalangeal joint implant, with the material being assumed to have isotropic elastic properties in one case while it was represented as hyperelastic in the other. The model used in the second study case was that of …a construct comprising the tibial component of a total knee replacement, the associated tibial insert, the resected bones, and the acrylic bone cement layer. In one analysis of this model, all the materials were taken to have isotropic elastic properties, while in the other analysis, the cortical bone was represented as transversely isotropic, with all other materials being considered to have isotropic elastic properties. The results show that, in both study cases considered, there is a strong effect of the representation of the elastic properties of material(s) on the stresses in the models. Show more

Keywords: Metacarpophalangeal joint, knee joint replacement, finite element analysis

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 1, pp. 11-23, 1998

Authors: Lewis, Gladius | Jonathan, Vinod | Kambhampati, Sarma

Article Type: Research Article

Abstract: The present study sought to examine if, and to what extent, the representation of the elastic properties of material(s) in a model of an endoprosthesis per se or a construct that includes an endoprosthesis affects the stresses in the model, when the finite element analysis method is used to obtain these stresses. For this purpose, two models were examined. One was of an elastomeric metacarpophalangeal joint implant, with the material being assumed to have isotropic elastic properties in one case while it was represented as hyperelastic in the other. The model used in the second study case was that of …a construct comprising the tibial component of a total knee replacement, the associated tibial insert, the resected bones, and the acrylic bone cement layer. In one analysis of this model, all the materials were taken to have isotropic elastic properties, while in the other analysis, the cortical bone was represented as transversely isotropic, with all other materials being considered to have isotropic elastic properties. The results show that, in both study cases considered, there is a strong effect of the representation of the elastic properties of material(s) on the stresses in the models. Show more

Keywords: Metacarpophalangeal joint, knee joint replacement, finite element analysis

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 1, pp. 11-23, 1998

Authors: Torres, F.J. | Panyayong, W. | Rogers, W. | Velasquez‐Plata, D. | Oshida, Y. | Moore, B.K.

Article Type: Research Article

Abstract: The present work investigates the corrosion behavior of 2205 duplex stainless steel in 0.9% NaCl solution after various heat‐treatments, and compares it to that of 316L austenitic stainless steel. Both stainless steels were heat‐treated at 500, 650, and 800^{\circ} C in air for 1 h, followed by furnace cooling. Each heat‐treated sample was examined for their microstructures and Vickers micro‐hardness, and subjected to the X‐ray diffraction for the phase identification. Using potentiostatic polarization method, each heat‐treated sample was corrosion‐tested in 37^{\circ} C 0.9% NaCl solution to estimate its corrosion rate. It was found that simulated sensitization showed an …adverse influence on both steels, indicating that corrosion rates increased by increasing the sensitization temperatures. Show more

Keywords: Sensitization, intergranular corrosion, duplex stainless steel, 316L stainless steel, 0.9% NaCl solution

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 1, pp. 25-36, 1998

Authors: Torres, F.J. | Panyayong, W. | Rogers, W. | Velasquez‐Plata, D. | Oshida, Y. | Moore, B.K.

Article Type: Research Article

Abstract: The present work investigates the corrosion behavior of 2205 duplex stainless steel in 0.9% NaCl solution after various heat‐treatments, and compares it to that of 316L austenitic stainless steel. Both stainless steels were heat‐treated at 500, 650, and 800^{\circ} C in air for 1 h, followed by furnace cooling. Each heat‐treated sample was examined for their microstructures and Vickers micro‐hardness, and subjected to the X‐ray diffraction for the phase identification. Using potentiostatic polarization method, each heat‐treated sample was corrosion‐tested in 37^{\circ} C 0.9% NaCl solution to estimate its corrosion rate. It was found that simulated sensitization showed an …adverse influence on both steels, indicating that corrosion rates increased by increasing the sensitization temperatures. Show more

Keywords: Sensitization, intergranular corrosion, duplex stainless steel, 316L stainless steel, 0.9% NaCl solution

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 1, pp. 25-36, 1998

Authors: Nordström, E.G. | Yokobori, Jr., A.T. | Yokobori, T. | Aizawa, Y.

Article Type: Research Article

Abstract: By using the fracture toughness estimation method based on two‐dimensional map, it was found that the ductility of the high porosity hydroxyapatite/mica composite was comparable with silicon carbide. It was measured to be higher than that of packed hydroxyapatite. Alumina ceramics with more than 96% aluminium oxide showed a higher fracture toughness than the composite material. When bending strength was compared, the strength of the composite was two or three times lower than that of packed hydroxyapatite and much lower than the other studied materials. The composite material showed high porosity, which in turn gives it a lower bending strength. …However, the high porosity is more favourable for biocompatibility. Show more

Keywords: Hydroxy(l)apatite, ceramic, composites, fracture toughness

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 1, pp. 37-43, 1998

Authors: Nordström, E.G. | Yokobori, Jr., A.T. | Yokobori, T. | Aizawa, Y.

Article Type: Research Article

Abstract: By using the fracture toughness estimation method based on two‐dimensional map, it was found that the ductility of the high porosity hydroxyapatite/mica composite was comparable with silicon carbide. It was measured to be higher than that of packed hydroxyapatite. Alumina ceramics with more than 96% aluminium oxide showed a higher fracture toughness than the composite material. When bending strength was compared, the strength of the composite was two or three times lower than that of packed hydroxyapatite and much lower than the other studied materials. The composite material showed high porosity, which in turn gives it a lower bending strength. …However, the high porosity is more favourable for biocompatibility. Show more

Keywords: Hydroxy(l)apatite, ceramic, composites, fracture toughness

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 1, pp. 37-43, 1998

Authors: Boyer, Daniel B. | Papadogiannis, Yannis | Park, H.C. | Lakes, Roderic S.

Article Type: Research Article

Abstract: Effects of aging on several dental composites were studied using a torsion creep apparatus. A constant torque was applied from 1 second to 3 hours, and recovery was observed from 10 seconds to 2 days, for specimens aged from 3 hours to 8 weeks following polymerization. Specimens aged for shorter times exhibited more creep and less complete recovery than specimens aged for longer times. Modulus and creep results were qualitatively consistent with a composite model for particulate inclusions.

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 1, pp. 45-53, 1998