6051
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Yamada K, Onizuka T, Endo K, Ohno H, Swain MV. The influence of GoldbonderTM and pre-heat treatment on the adhesion of titanium alloy and porcelain. J Oral Rehabil 2005; 32:213-20. [PMID: 15707432 DOI: 10.1111/j.1365-2842.2004.01408.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The present study examines the influence of a goldbonder and pre-heat treatment of the titanium on the adhesion of porcelain. Three groups of titanium substrates were given various heat treatments, namely; none, 200 degrees and 600 degrees C, respectively before applying goldbonder. The surfaces of the titanium specimens following heat treatment were examined with an electron spectroscopy for chemical analysis (ESCA). The adhesion strength was measured by the strain energy release rate (G), which was proposed by Suansuwan N and Swain MV (Int J Prosthodont. 1999;12:547). After bonding porcelain onto titanium substrates with the aid of the goldbonder, the porcelain side of specimens was notched to the interface with a thin diamond saw. Then the samples were subject to a four-point bending test. Following fracture testing, specimens were examined with a scanning electron microscope (SEM) and SEM with energy-dispersive spectroscopic analysis (EDS). The mean G-values were 38.87, 28.64 and 16.33 J m(-2), respectively. ESCA analysis showed the composition of aluminium of the surface of 600 degrees C pre-heat treatment became richer than that of the others. SEM images of the fracture surfaces showed that for the 600 degrees C pre-heat treatment fracture occurred within the oxidation layer on the titanium. High temperature pre-heat treatment prior to bonding significantly reduces porcelain bonded to titanium with the goldbonder. The Influence of Goldbonder and Pre-heat Treatment on the Adhesion of Titanium Alloy and Porcelain.
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Affiliation(s)
- K Yamada
- Biomaterials Science Research Unit, Faculty of Dentistry, The University of Sydney, National Innovation Centre, Australian Technology Park, Eveleigh, NSW, Australia
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6052
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Lavagnino M, Arnoczky SPSP, Frank K, Tian T. Collagen fibril diameter distribution does not reflect changes in the mechanical properties of in vitro stress-deprived tendons. J Biomech 2005; 38:69-75. [PMID: 15519341 DOI: 10.1016/j.jbiomech.2004.03.035] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2004] [Indexed: 11/23/2022]
Abstract
The purpose of this study was to determine if an association exists between the tensile properties and the collagen fibril diameter distribution in in vitro stress-deprived rat tail tendons. Rat tail tendons were paired into two groups of 21 day stress-deprived and 0 time controls and compared using transmission electron microscopy (n = 6) to measure collagen fibril diameter distribution and density, and mechanical testing (n =6) to determine ultimate stress and tensile modulus. There was a statistically significant decrease in both ultimate tensile strength (control: 17.95+/-3.99 MPa, stress-deprived: 6.79+/-3.91 MPa) and tensile modulus (control: 312.8+/-89.5 MPa, stress-deprived: 176.0+/-52.7 MPa) in the in vitro stress-deprived tendons compared to controls. However, there was no significant difference between control and stress-deprived tendons in the number of fibrils per tendon counted, mean fibril diameter, mean fibril density, or fibril size distribution. The results of this study demonstrate that the decrease in mechanical properties observed in in vitro stress-deprived rat tail tendons is not correlated with the collagen fibril diameter distribution and, therefore, the collagen fibril diameter distribution does not, by itself, dictate the decrease in mechanical properties observed in in vitro stress-deprived rat tail tendons.
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Affiliation(s)
- Michael Lavagnino
- Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
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6053
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Influence of Surface Polishing on the Electrochemical Behavior of Titanium. ACTA ACUST UNITED AC 2005. [DOI: 10.1149/1.1996509] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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6054
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Abstract
Wear behavior of titanium materials such as C.P.Ti, Ti-6Al-4V and Ti-6Al-7Nb, was studied in simulated body fluids by means of the pin-on-disk type wear testing. The mass loss in wear testing increased with increasing the sliding distance. The a+b type titanium alloys, Ti-6Al-4V and Ti-6Al-7Nb, exhibited higher wear resistance than the C.P.Ti. Average size of the wear debris was 4.5 µm and 3.7 µm for C.P.Ti and the a+b type titanium alloys, respectively. The elution of metallic constituents into 1 mass% lactic acid solution was detected after the wear test.
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6055
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Gall K, Tyber J, Brice V, Frick CP, Maier HJ, Morgan N. Tensile deformation of NiTi wires. J Biomed Mater Res A 2005; 75:810-23. [PMID: 16138359 DOI: 10.1002/jbm.a.30464] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We examine the structure and properties of cold drawn Ti-50.1 at % Ni and Ti-50.9 at % Ni shape memory alloy wires. Wires with both compositions possess a strong <111> fiber texture in the wire drawing direction, a grain size on the order of micrometers, and a high dislocation density. The more Ni rich wires contain fine second phase precipitates, while the wires with lower Ni content are relatively free of precipitates. The wire stress-strain response depends strongly on composition through operant deformation mechanisms, and cannot be explained based solely on measured differences in the transformation temperatures. We provide fundamental connections between the material structure, deformation mechanisms, and resulting stress-strain responses. The results help clarify some inconsistencies and common misconceptions in the literature. Ramifications on materials selection and design for emerging biomedical applications of NiTi shape memory alloys are discussed.
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Affiliation(s)
- Ken Gall
- Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
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6056
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Osseointegration study of porous nitinol versus titanium orthopaedic implants. EUROPEAN JOURNAL OF ORTHOPAEDIC SURGERY AND TRAUMATOLOGY 2004. [DOI: 10.1007/s00590-004-0176-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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6057
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Lee SJ, Choi JS, Park KS, Khang G, Lee YM, Lee HB. Response of MG63 osteoblast-like cells onto polycarbonate membrane surfaces with different micropore sizes. Biomaterials 2004; 25:4699-707. [PMID: 15120516 DOI: 10.1016/j.biomaterials.2003.11.034] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2003] [Accepted: 11/24/2003] [Indexed: 11/20/2022]
Abstract
Response of different types of cells on materials is important for the applications of tissue engineering and regenerative medicine. It is recognized that the behavior of the cell adhesion, proliferation, and differentiation on materials depends largely on surface characteristics such as wettability, chemistry, charge, rigidity, and roughness. In this study, we examined the behavior of MG63 osteoblast-like cells cultured on a polycarbonate (PC) membrane surfaces with different micropore sizes (0.2-8.0 microm in diameter). Cell adhesion and proliferation to the PC membrane surfaces were determined by cell counting and MTT assay. The effect of surface micropore on the MG63 cells was evaluated by cell morphology, protein content, and alkaline phosphatase (ALP) specific activity. It seems that the cell adhesion and proliferation were progressively inhibited as the PC membranes had micropores with increasing size, probably due to surface discontinuities produced by track-etched pores. Increasing micropore size of the PC membrane results in improved protein synthesis and ALP specific activity in isolated cells. There was a statistically significant difference (P<0.05) between different micropore sizes. The MG63 cells also maintained their phenotype under conditions that support a round cell shape. RT-PCR analysis further confirmed the osteogenic phenotype of the MG63 cells onto the PC membranes with different micropore sizes. In results, as micropore size is getting larger, cell number is reduced and cell differentiation and matrix production is increased. This study demonstrated that the surface topography plays an important role for phenotypic expression of the MG63 osteoblast-like cells.
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Affiliation(s)
- Sang Jin Lee
- Biomaterials Laboratory, Korea Research Institute of Chemical Technology, 100 Jang-dong Yuseong-gu, Daejeon 305-600, South Korea
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6058
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Banerjee R, Nag S, Stechschulte J, Fraser HL. Strengthening mechanisms in Ti–Nb–Zr–Ta and Ti–Mo–Zr–Fe orthopaedic alloys. Biomaterials 2004; 25:3413-9. [PMID: 15020114 DOI: 10.1016/j.biomaterials.2003.10.041] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2003] [Accepted: 10/11/2003] [Indexed: 11/21/2022]
Abstract
The microstructural evolution and attendant strengthening mechanisms in two novel orthopaedic alloy systems, Ti-Nb-Zr-Ta and Ti-Mo-Zr-Fe, have been compared and contrasted in this paper. Specifically, the alloy compositions considered are Ti-34Nb-9Zr-8Ta and Ti-13Mo-7Zr-3Fe. In the homogenized condition, both alloys exhibited a microstructure consisting primarily of a beta matrix with grain boundary alpha precipitates and a low-volume fraction of intra-granular alpha precipitates. On ageing the homogenized alloys at 600 degrees C for 4 hr, both alloys exhibited the precipitation of refined scale secondary alpha precipitates homogeneously in the beta matrix. However, while the hardness of the Ti-Mo-Zr-Fe alloy marginally increased, that of the Ti-Nb-Zr-Ta alloy decreased substantially as a result of the ageing treatment. In order to understand this difference in the mechanical properties after ageing, TEM studies have been carried out on both alloys prior to and post the ageing treatment. The results indicate the existence of a metastable B2 ordering in the Ti-Nb-Zr-Ta alloy in the homogenized condition which is destroyed by the ageing treatment, consequently leading to a decrease in the hardness.
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Affiliation(s)
- Rajarshi Banerjee
- Department of Materials Science and Engineering, The Ohio State University, 477 Watts Hall, 2041 College Road, Columbus, OH 43210, USA.
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6059
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Almirall A, Larrecq G, Delgado JA, Martínez S, Planell JA, Ginebra MP. Fabrication of low temperature macroporous hydroxyapatite scaffolds by foaming and hydrolysis of an α-TCP paste. Biomaterials 2004; 25:3671-80. [PMID: 15020142 DOI: 10.1016/j.biomaterials.2003.10.066] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2003] [Accepted: 10/10/2003] [Indexed: 11/23/2022]
Abstract
The development of the new technologies of bone tissue engineering requires the production of bioresorbable macroporous scaffolds. Calcium phosphate cements are good candidate materials for the development of these scaffolds, as an alternative to the traditional porous sintered ceramics. In this work a novel two-step method, based in the foaming of an alpha-tricalcium phosphate (alpha-TCP) cement paste and its subsequent hydrolysis to a calcium deficient hydroxyapatite (CDHA) is presented. The foaming agent was a hydrogen peroxide (H2O2) solution, which decomposes in water and oxygen gas. CDHA foams, which combined an interconnected macroporosity with a high microporosity were obtained. The apatitic phase obtained by the hydrolysis reaction was more similar to the biologic one, in terms of chemical composition, crystallinity and specific surface than the hydroxyapatites obtained by sintering. The percentage of porosity in the foams reached a 66%. It was shown that it was possible to control the porosity, and pore size and shape by different processing parameters such as the liquid-to-powder ratio, the concentration of the H2O2 solution and the particle size of the powder.
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Affiliation(s)
- A Almirall
- Biomaterials Division, Department of Materials Science and Metallurgy, Biomedical Engineering Research Centre, Technical University of Catalonia (UPC), Av. Diagonal 647, E08028 Barcelona, Spain
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6060
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Schiff N, Grosgogeat B, Lissac M, Dalard F. Influence of fluoridated mouthwashes on corrosion resistance of orthodontics wires. Biomaterials 2004; 25:4535-42. [PMID: 15120498 DOI: 10.1016/j.biomaterials.2003.11.042] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2003] [Accepted: 11/24/2003] [Indexed: 11/29/2022]
Abstract
The aim of the present study was to classify the different alloys commonly used to make orthodontic wire according to their corrosion resistance in different media. The four materials analysed were titanium-based alloys: TMA, TiNb, NiTi and CuNiTi, which were tested in three fluoride mouthwashes: Elmex, Meridol and Acorea as well as in Fusayama Meyer artificial saliva. The electrochemical study showed that the alloys could be divided into two groups. In one group were the NiTi-based alloys which were subject to strong corrosion in the presence of monofluorophosphate found in Acorea solution. In the other group were TiNb, which was the most resistant to corrosion, and TMA, which corroded strongly with the stannous fluoride found in Meridol mouthwash. The results obtained in the present study will enable us to provide attending practitioners with advice concerning fluoride mouthwash to recommend, depending on the treatment phase and the alloy used. So we can advise Elmex mouthwash for patients with TMA and NiTi-based orthodontics wires but we suggest Acorea or Meridol mouthwashes for patients with TiNb orthodontics wires.
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Affiliation(s)
- Nicolas Schiff
- School of Dentistry, University Claude Bernard Lyon 1, Interfaces and Biofilms Study Laboratory in Odontology, EA 637, Rue Guillaume Paradin, 69372 Lyon Cedex 08, France.
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6061
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Hildebrand KA, Holmberg M, Shrive N. A new method to measure post-traumatic joint contractures in the rabbit knee. J Biomech Eng 2004; 125:887-92. [PMID: 14986415 PMCID: PMC3712980 DOI: 10.1115/1.1634285] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A new device and method to measure rabbit knee joint angles are described. The method was used to measure rabbit knee joint angles in normal specimens and in knee joints with obvious contractures. The custom-designed and manufactured gripping device has two clamps. The femoral clamp sits on a pinion gear that is driven by a rack attached to a materials testing system. A 100 N load cell in series with the rack gives force feedback. The tibial clamp is attached to a rotatory potentiometer. The system allows the knee joint multiple degrees-of-freedom (DOF). There are two independent DOF (compression-distraction and internal-external rotation) and two coupled motions (medial-lateral translation coupled with varus-valgus rotation; anterior-posterior translation coupled with flexion-extension rotation). Knee joint extension-flexion motion is measured, which is a combination of the materials testing system displacement (converted to degrees of motion) and the potentiometer values (calibrated to degrees). Internal frictional forces were determined to be at maximum 2% of measured loading. Two separate experiments were performed to evaluate rabbit knees. First, normal right and left pairs of knees from four New Zealand White (NZW) rabbits were subjected to cyclic loading. An extension torque of 0.2 Nm was applied to each knee. The average change in knee joint extension from the first to the fifth cycle was 1.9 deg +/- 1.5 deg (mean +/- sd) with a total of 49 tests of these eight knees. The maximum extension of the four left knees (tested 23 times) was 14.6 deg +/- 7.1 deg, and of the four right knees (tested 26 times) was 12.0 deg +/- 10.9 deg. There was no significant difference in the maximum extension between normal left and right knees. In the second experiment, nine skeletally mature NZW rabbits had stable fractures of the femoral condyles of the right knee that were immobilized for five, six or 10 weeks. The left knee served as an unoperated control. Loss of knee joint extension (flexion contracture) was demonstrated for the experimental knees using the new methodology where the maximum extension was 35 deg +/- 9 deg, compared to the unoperated knee maximum extension of 11 deg +/- 7 deg, 10 or 12 weeks after the immobilization was discontinued. The custom gripping device coupled to a materials testing machine will serve as a measurement test for future studies characterizing a rabbit knee model of post-traumatic joint contractures.
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Affiliation(s)
- Kevin A Hildebrand
- Department of Surgery, University of Calgary, 3330 Hospital Dr NW, Calgary, AB, Canada T2N 4N1.
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6062
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Kjaer M. Role of extracellular matrix in adaptation of tendon and skeletal muscle to mechanical loading. Physiol Rev 2004; 84:649-98. [PMID: 15044685 DOI: 10.1152/physrev.00031.2003] [Citation(s) in RCA: 951] [Impact Index Per Article: 47.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The extracellular matrix (ECM), and especially the connective tissue with its collagen, links tissues of the body together and plays an important role in the force transmission and tissue structure maintenance especially in tendons, ligaments, bone, and muscle. The ECM turnover is influenced by physical activity, and both collagen synthesis and degrading metalloprotease enzymes increase with mechanical loading. Both transcription and posttranslational modifications, as well as local and systemic release of growth factors, are enhanced following exercise. For tendons, metabolic activity, circulatory responses, and collagen turnover are demonstrated to be more pronounced in humans than hitherto thought. Conversely, inactivity markedly decreases collagen turnover in both tendon and muscle. Chronic loading in the form of physical training leads both to increased collagen turnover as well as, dependent on the type of collagen in question, some degree of net collagen synthesis. These changes will modify the mechanical properties and the viscoelastic characteristics of the tissue, decrease its stress, and likely make it more load resistant. Cross-linking in connective tissue involves an intimate, enzymatical interplay between collagen synthesis and ECM proteoglycan components during growth and maturation and influences the collagen-derived functional properties of the tissue. With aging, glycation contributes to additional cross-linking which modifies tissue stiffness. Physiological signaling pathways from mechanical loading to changes in ECM most likely involve feedback signaling that results in rapid alterations in the mechanical properties of the ECM. In developing skeletal muscle, an important interplay between muscle cells and the ECM is present, and some evidence from adult human muscle suggests common signaling pathways to stimulate contractile and ECM components. Unaccostumed overloading responses suggest an important role of ECM in the adaptation of myofibrillar structures in adult muscle. Development of overuse injury in tendons involve morphological and biochemical changes including altered collagen typing and fibril size, hypervascularization zones, accumulation of nociceptive substances, and impaired collagen degradation activity. Counteracting these phenomena requires adjusted loading rather than absence of loading in the form of immobilization. Full understanding of these physiological processes will provide the physiological basis for understanding of tissue overloading and injury seen in both tendons and muscle with repetitive work and leisure time physical activity.
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Affiliation(s)
- Michael Kjaer
- Sports Medicine Research Unit, Department of Rheumatology, Copenhagen University Hospital at Bispebjerg, 23 Bispebjerg Bakke, DK-2400 Copenhagen NV, Denmark.
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6063
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Abstract
Long-term tissue response to a metal device is described here. The components of a spinal fixation device were removed 6 years after implantation, following the need for revision surgery after a fall. Scanning electron microscopy (SEM) revealed changes in surface topography of the metal. Examination of the adjacent tissue showed a chronic inflammatory response with occasional metal debris. Immunohistochemistry identified the predominant macrophages and abundant neovascularization. The presence of macrophages in tissues adjacent to the implants, in an otherwise asymptomatic person, is noteworthy.
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Affiliation(s)
- Mira Mohanty
- Division of Implant Biology, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala-695012, India.
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6064
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Gross KA, Rodríguez-Lorenzo LM. Sintered hydroxyfluorapatites. Part II: Mechanical properties of solid solutions determined by microindentation. Biomaterials 2004; 25:1385-94. [PMID: 14643613 DOI: 10.1016/s0142-9612(03)00636-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fluoride substitution within hydroxyapatite is an important occurrence for biological apatites and is a promising approach for the chemical modification of synthetic hydroxyapatite. Limited information on the influence of fluoride substitution for hydroxyl groups on the mechanical properties has provided the rationale for this study. Hydroxyfluorapatites with 0%, 20%, 40%, 60%, 80% and 100% replacement of hydroxyl groups with fluoride ions were assessed for hardness, elastic modulus, fracture toughness and brittleness using microindentation of sintered pellets. The production of samples with a similar grain size and density allowed the influence of fluoride on mechanical properties to be determined. It was found that the hardness remains unaffected until 80% replacement of hydroxyl groups with fluoride, after which the hardness rapidly increases. The elastic modulus increases linearly with fluoride content. Fracture toughness is improved with fluoride incorporation into the lattice and reaches a peak of 1.8 for a 95% dense sintered pellet with a 60% fluoride replacement, followed by a rapid decrease at higher fluoride concentrations. The brittleness index is lowered to a minimum at 60%, after which a rapid increase occurs. High fluoride levels are unfavourable from a mechanical perspective, are not recommended for biomaterials, and can lead to a higher incidence of fracture where sodium fluoride, for treatment of osteoporosis, may produce a highly fluoridated hydroxyapatite.
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Affiliation(s)
- Kārlis A Gross
- School of Physics and Materials Engineering, Building 69, Monash University, VIC 3800, Australia.
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6065
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Hildebrand KA, Sutherland C, Zhang M. Rabbit knee model of post-traumatic joint contractures: the long-term natural history of motion loss and myofibroblasts. J Orthop Res 2004; 22:313-20. [PMID: 15013090 DOI: 10.1016/j.orthres.2003.08.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/11/2003] [Indexed: 02/04/2023]
Abstract
Our objective is to describe the natural history of motion loss with time and myofibroblast numbers in a rabbit knee model of post-traumatic joint contractures. Twenty-eight skeletally mature New Zealand White female rabbits had five-mm-squares of cortical bone removed from the medial and lateral femoral condyles of the right knee. A Kirschner wire (K-wire) was used to immobilize the knee joint in maximum flexion. A second operation was performed 8 weeks later to remove the K-wire. The rabbits were divided into four groups depending on the time of remobilization; 0, 8, 16 or 32 weeks. The average flexion contracture of the experimental knees in the 0-week and 8-week remobilization groups (38 degrees and 33 degrees, respectively) were significantly greater when compared with the values of the unoperated contralateral knees (8 degrees). The average flexion contractures of the experimental knees in the 16-week and 32-week remobilization groups were also greater than the unoperated contralateral knees, although they were not statistically significant. The average flexion contractures of the 16-week and 32-week groups were 19 degrees and 18 degrees, respectively, indicating a stabilization of the motion loss. Myofibroblast numbers in the posterior joint capsules were elevated 4-5x in the knees with contractures when compared to the contralateral knees. The initial decrease in severity followed by stabilization of motion loss and the association of motion loss with myofibroblasts mimics the human scenario of permanent post-traumatic joint contractures.
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Affiliation(s)
- Kevin A Hildebrand
- Department of Surgery, University of Calgary, 3330 Hospital Dr NW, Calgary, AB, Canada T2N 4N1.
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6066
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Oooka S, Miyazaki M, Takamizawa T, Tsubota K, Kurokawa H, Rikuta A. Influence of adhesive polymerization mode on dentin bond strength of direct core foundation systems. J Oral Sci 2004; 46:185-9. [PMID: 15508752 DOI: 10.2334/josnusd.46.185] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
This study examined the influence of various adhesive systems on dentin bond strength of direct core foundation resins. Two commercially available direct core foundation resin systems and 2 adhesive polymerization modes were used. Facial bovine dentin surfaces were wet ground on 600-grit SiC paper. Dentin surfaces were treated according to the manufacturers' instructions and were light polymerized (control). Chemical- and light-polymerized adhesive systems were used separately. The resin paste was condensed into a mold and bonded to the dentin surface. Ten specimens per test group were stored in water at 37 degrees C for 24 hours, and a shear test was conducted at a crosshead speed of 1.0 mm/minute using a universal testing machine. Analysis of variance (ANOVA) and Duncan's multiple comparison test were performed (alpha = 0.05). Dual polymerization of resin pastes revealed higher bond strength with the combination of light-polymerized adhesive (22.8-24.3 MPa), but significantly lower bond strength with the combination of a chemical-polymerized adhesive (4.2-5.7 MPa). The present data suggests that dentin bond strengths in direct core foundation systems can be influenced by the combination of adhesive and resin paste.
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Affiliation(s)
- Satoshi Oooka
- Nihon University Graduate School of Dentistry, Tokyo, Japan
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6067
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Moriyama H, Yoshimura O, Sunahori H, Nitta H, Imakita H, Saka Y, Maejima H, Tobimatsu Y. Progression and Direction of Contractures of Knee Joints Following Spinal Cord Injury in the Rat. TOHOKU J EXP MED 2004; 204:37-44. [PMID: 15329461 DOI: 10.1620/tjem.204.37] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Joint contractures following central nervous system injuries remain a prevalent and significant complication, but no reports are available on evidence of contracture formation over time. The objective of this study was to determine the rate of contracture progression and the direction of loss in joint movement following spinal cord injuries (SCI). Forty-eight female Wistar rats were used. Twenty-four experimental rats underwent a spinal cord transection at the level of T8 and 24 control rats underwent a sham-operation. The animals were studied at each of 5 time points: 2, 4, 8, 12, 16, and 24 weeks after surgical intervention. The degree of contractures was assessed by measuring the femorotibial angle on both hindlimbs with the use of a goniometer. Knee joint motion was measured for flexion and extension direction. Knee flexion contractures developed in all experimental rats. The restriction in motion progressed during the first 12 weeks and plateaued thereafter. The contractures were produced almost exclusively by a loss in the extension range of motion. This study defined the time course that contracture progression was more rapid in the early stage after SCI and stabilized in the later stage of injury. Contractures following SCI occurred in flexion at the knees and resulted from a loss of extension. These findings should help guide timely treatment and provide a better understanding of contracture development.
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Affiliation(s)
- Hideki Moriyama
- Graduate School of Health Science, Hiroshima University, Japan.
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6068
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Watanabe I, Topham DS. Tensile strength and elongation of laser-welded Ti and Ti-6AL-7NB. ACTA ACUST UNITED AC 2004; 71:46-51. [PMID: 15368227 DOI: 10.1002/jbm.b.30058] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This study established data demonstrating the possible laser-welded strengths of cast Ti and Ti-6Al-7Nb and compared them to those of two dental-casting alloys. Cast plates of Ti, Ti-6Al-7Nb, gold, and Co-Cr alloy were prepared. After polishing the surfaces to be welded, two plates were abutted and welded using an Nd:YAG laser at a pulse duration of 10 ms, spot diameter of 1 mm, and voltage of 200 V. Five specimens were prepared for each metal by welding either three or five spots unilaterally or bilaterally. The fracture load and percent elongation were measured at a crosshead speed of 1.0 mm/min. The bilaterally welded specimens performed significantly greater than unilaterally welded specimens in both fracture load and elongation whether they were welded with three or five spots per side. The bilaterally welded Ti and Ti-6Al-7Nb specimens were nearly as strong as their corresponding control specimens, whereas the gold and Co-Cr specimens were approximately half as strong. When a large proportion of the cross-sectional area of the joint is laser welded, the strength of the laser-welded portion of the cast Ti and Ti-6Al-7Nb may approach or equal that of the nonwelded metal frameworks.
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Affiliation(s)
- Ikuya Watanabe
- Department of Biomaterials Science, Baylor College of Dentistry, Texas A and M University System Health Science Center, 3302 Gaston Avenue, Dallas, Texas 75246, USA.
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6069
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Shabalovskaya S, Rondelli G, Anderegg J, Xiong JP, Wu M. Comparative corrosion performance of black oxide, sandblasted, and fine-drawn nitinol wires in potentiodynamic and potentiostatic tests: Effects of chemical etching and electropolishing. ACTA ACUST UNITED AC 2004; 69:223-31. [PMID: 15116412 DOI: 10.1002/jbm.b.30006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The corrosion performance of sandblasted (SB) and smooth fine-drawn (FD) medical-use nitinol wires was compared with the performance of wires with black oxide (BO) formed in air during their manufacture. Potentiodynamic and ASTM F746 potentiostatic tests in a 0.9 % NaCl solution were conducted on wires in their as-received, chemically etched, aged in boiling water, and electropolished states. As-received wires with various surface finishes revealed breakdown potentials in the range from -100 mV to +500 mV; similar passive current density, 10(-6) A/cm(2); and a wide hysteresis on the reverse scan, demonstrating strong susceptibility to localized corrosion. Chemically etched wires with original black oxide displayed consistent corrosion performance and surpassed, in corrosion resistance, electropolished wires that showed significantly lower breakdown (400-700 mV) and localized corrosion potentials ( approximately -50 to +113 mV). Sandblasted and fine-drawn wires exhibited rather inconsistent corrosion behavior. In potentiodynamic tests these wires could perform with equal probability either on the level of pretreated BO wires or rather similar to as-received wires. Both SB and FD wires revealed low breakdown potentials in the PS regime. SEM analysis performed before tests indicated that sandblasting was not efficient for the complete removal of the original scaling, and fine drawing aggravated the situation, resulting in a persistent scaling that contributed to the inferior corrosion performance. Inclusions (oxides, carbides, and oxidized carbides) inherited from the bulk and retained on electropolished surfaces are the cause of their inferior performance compared to chemically etched surfaces. In electropolished wires corrosion was initiated around inclusions.
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6070
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Lee SJ, Lee YM, Han CW, Lee HB, Khang G. Response of human chondrocytes on polymer surfaces with different micropore sizes for tissue-engineered cartilage. J Appl Polym Sci 2004. [DOI: 10.1002/app.20281] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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6071
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6072
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6073
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Hunter G, Lane DM, Scrimgeour SN, McDonald PJ, Lloyd CH. Measurement of the diffusion of liquids into dental restorative resins by stray-field nuclear magnetic resonance imaging (STRAFI). Dent Mater 2003; 19:632-8. [PMID: 12901988 DOI: 10.1016/s0109-5641(03)00006-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES The purpose of this investigation was to determine the diffusion mechanism for water/ethanol mixtures in a diacrylate dental resin by direct observation of the absorbed liquid profiles using NMR microimaging. METHODS Frequency-swept stray-field magnetic resonance imaging (STRAFI) was used. Solutions containing 25-65% by volume ethanol remained in contact with visible light cured 54% TEGDMA: 46% modified TUDMA sheets while measurements were made. The diffusion profiles were recorded periodically for diffusion times up to 10 h, to a depth of 360 microm and with readings taken at 24 microm intervals. RESULTS For all liquid mixtures, diffusion was found to be Fickian with coefficients that increased progressively and smoothly with alcohol content in the diffusing mixture, from 2.4 x 10(-13) to 150 x 10(-13) m2 s(-1). A rule of mixtures approach, as suggested by Kwei and Zupko, gave a satisfactory description of the ethanol fraction dependence of the diffusivity. SIGNIFICANCE Frequency-swept STRAFI offers a new and unique opportunity to produce spatially resolved measurements of the liquids in dental resins to high resolution. In this study, absorption was investigated since an understanding of its mechanism is fundamental to limiting consequent environmental degradation. STRAFI has great potential for other applications, for example drying, liquid exchange, etc. Since STRAFI can discriminate 1H in the liquid from those in softened polymer additional applications are envisaged.
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Affiliation(s)
- Geoffrey Hunter
- Division of Physical and Inorganic Chemistry, School of Life Sciences, University of Dundee, Dundee DD1 4HN, Scotland UK
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6074
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Manceur A, Chellat F, Merhi Y, Chumlyakov Y, Yahia L. In vitro cytotoxicity evaluation of a 50.8% NiTi single crystal. ACTA ACUST UNITED AC 2003; 67:641-6. [PMID: 14566808 DOI: 10.1002/jbm.a.10134] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
To our knowledge, the biocompatibility of nickel-titanium (NiTi) single crystals has not been reported. Yet certain orientations of single crystals present several advantages over the polycrystalline form in terms of maximal strain, fatigue resistance, and temperature range of superelasticity. Therefore we tested the in vitro biocompatibility of 50.8% NiTi single crystals in the orientation <001> after four different heat treatments in a helium atmosphere followed by mechanical polishing. The study was performed on the material extracts after immersion of the specimens in cell culture medium (DMEM) for 7 days at 37 degrees C. Cytotoxicity studies were performed on L-929 mouse fibroblasts using the MTT assay. J-774 macrophages were used to assess the potential inflammatory effect of the extracts by IL1-beta and TNF-alpha dosages (sandwich ELISA method). Exposure of L-929 to material extracts did not affect cell viability. In addition, IL1-beta and TNF-alpha secretion was not stimulated after incubation with NiTi extracts compared to the negative controls. These results were predictable since atomic absorption spectroscopy did not detect nickel ions in the extracts with a resolution of 1 ppm. Within the limits of in vitro testing, our results demonstrate that the TiNi(50.8%) single crystals do not trigger a cytotoxic reaction.
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Affiliation(s)
- Aziza Manceur
- Biomedical Engineering Institute, Biomechanics and Biomaterials Research Group, Ecole Polytechnique, Station Downtown, P.O. Box 6079, Montréal, Québec, H3C 3A7, Canada.
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6075
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Shibata N, Tomita N, Onmori N, Kato K, Ikeuchi K. Defect initiation at subsurface grain boundary as a precursor of delamination in ultrahigh molecular weight polyethylene. ACTA ACUST UNITED AC 2003; 67:276-84. [PMID: 14517887 DOI: 10.1002/jbm.a.10133] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In order to examine the initiation mechanism of delamination in ultrahigh molecular weight polyethylene (UHMWPE) knee components, a bi-directional sliding fatigue test was performed for three types of UHMWPE specimens: nonirradiated, gamma-irradiated (25 kGy) and gamma-irradiated (25 kGy) with 0.1% vitamin E added. Sliding surfaces of post-tested UHMWPE specimens were observed using an optical microscope and a scanning electron microscope. Also, surface roughness was measured at the sliding surfaces of UHMWPE specimens. Delamination was observed only in gamma-irradiated specimens. A networked structure of surface asperity that resembled grain boundary was observed prior to delamination in gamma-irradiated specimens. Surface roughness in the gamma-irradiated specimens, higher than in any other specimen, showed a rapid increase prior to delamination. Detailed observation using an optical microscope and a scanning electron microscope showed microscopic crack initiation along subsurface grain boundaries in gamma-irradiated specimens. These results suggest that subsurface crack initiation is a precursor of delamination and is accelerated by oxidative degradation due to gamma irradiation. Of the three types of specimens, UHMWPE with vitamin E added showed the lowest surface roughness values at all measuring points. The addition of vitamin E is effective in improving wear resistance and fatigue performance of UHMWPE.
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Affiliation(s)
- Nobuyuki Shibata
- National Institute of Industrial Health, 6-21-1, Nagao, Tama-ku, Kawasaki 214, Japan
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6076
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Pistorius A, Willershausen B, Briseño Marroquin B. Effect of apical root-end filling materials on gingival fibroblasts. Int Endod J 2003; 36:610-5. [PMID: 12950575 DOI: 10.1046/j.1365-2591.2003.00698.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIM To determine the influence of root-end filling materials on specific cellular responses of gingival fibroblasts (GF). METHODOLOGY The reactions of cells in contact with mineral trioxide aggregate (MTA), amalgam and a chemically inert titanium alloy were determined based on the assessment of prostaglandin (PGE2) release with and without arachidonic acid stimulation, protein and lactate synthesis, and cell proliferation. Cells cultured without test materials served as controls (100%). RESULTS The fibroblasts showed a highly significant decrease in protein synthesis when in contact with amalgam (61.8 +/- 13.6%); MTA (91.2 +/- 5.9%) and titanium (92.4 +/- 4.7%) had little effect on this parameter. The rate of cell proliferation in contact with MTA (98.0 +/- 1.6%) and titanium (97.9 +/- 7.4%) was only slightly influenced and showed similar values to that of the controls after 96 h of incubation. On the contrary, a significant and continuous reduction in the rate of cell proliferation was observed for cells in contact with amalgam (61.0 +/- 2.5%) after 96 h. No significant increases in lactate synthesis values were registered for any of the materials (MTA 101.8 +/- 1.7%, titanium 94.8 +/- 8.6% and amalgam 105.8 +/- 10.3%). There was a significant decrease in PGE2 synthesis potential when cells were in contact with amalgam (85.2 +/- 3.5%). In comparison to the controls, titanium and MTA resulted in an elevated level of cellular PGE2 synthesis (titanium: 131.6 +/- 19.1%; MTA: 147.3 +/- 18.9%). The cell cultures stimulated with arachidonic acid (10-5 m) showed no significant differences with any material (MTA: 88.8 +/- 17.6%, titanium: 97.6 +/- 14.4%, amalgam: 85.5 +/- 16.8%). CONCLUSIONS MTA demonstrated cellular responses similar to those of titanium. Amalgam showed an irritation rate higher than that of MTA and titanium.
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Affiliation(s)
- A Pistorius
- Department of Operative Dentistry, Johannes Gutenberg-University, Mainz, Germany
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6077
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Laskin RS. The need for alternative bearings. Orthopedics 2003; 26:966, 968. [PMID: 14503768 DOI: 10.3928/0147-7447-20030901-37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Richard S Laskin
- Knee Service, The Institute for Hip and Knee Replacement, Hospital for Special Surgery, New York, NY 10021, USA
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6078
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Liao YS, McKellop H, Lu Z, Campbell P, Benya P. The effect of frictional heating and forced cooling on the serum lubricant and wear of UHMW polyethylene cups against cobalt-chromium and zirconia balls. Biomaterials 2003; 24:3047-59. [PMID: 12895577 DOI: 10.1016/s0142-9612(03)00148-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Hip simulator tests of femoral balls of cobalt-chromium alloy or zirconia against acetabular cups of UHMW polyethylene were run with and without a coolant circulated inside the femoral balls. Without cooling, the wear of polyethylene against zirconia was about 48% lower than with cobalt-chromium alloy, but the steady-state temperature of the zirconia ball was higher (55 degrees C vs. 41 degrees C), and there was more precipitation of protein from the serum, which sometimes formed an adherent layer on the surface of the zirconia. Circulating coolant at 1-20 degrees C markedly reduced the bearing temperatures and the protein precipitation. With coolant at 4 degrees C, wear of the polyethylene against cobalt-chromium alloy was about 26% lower than against zirconia, but the macroscopic and microscopic appearance of the worn polyethylene surfaces were unlike that typically generated in vivo. With or without coolant, the morphology of the polyethylene wear debris was comparable to that generated in vivo, but the ratio of fibrillar to granular debris was higher at the reduced temperature. These results suggested that circulating coolant at an appropriate temperature could avoid overheating (due to non-stop running of the simulator), preventing excessive protein precipitation while providing wear surfaces and wear debris with morphologies closely comparable to those generated in vivo.
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Affiliation(s)
- Y-S Liao
- The J. Vernon Luck Orthopaedic Research Center, Orthopaedic Hospital/UCLA, Los Angeles, CA, USA.
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6079
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Abstract
Shape memory alloys (SMA) are materials that have the ability to return to a former shape when subjected to an appropriate thermomechanical procedure. Pseudoelastic and shape memory effects are some of the behaviors presented by these alloys. The unique properties concerning these alloys have encouraged many investigators to look for applications of SMA in different fields of human knowledge. The purpose of this review article is to present a brief discussion of the thermomechanical behavior of SMA and to describe their most promising applications in the biomedical area. These include cardiovascular and orthopedic uses, and surgical instruments.
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Affiliation(s)
- L G Machado
- Departamento de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, Rio de Janeiro, RJ, Brasil
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6080
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Yokoyama K, Kaneko K, Moriyama K, Asaoka K, Sakai J, Nagumo M. Hydrogen embrittlement of Ni-Ti superelastic alloy in fluoride solution. J Biomed Mater Res A 2003; 65:182-7. [PMID: 12734810 DOI: 10.1002/jbm.a.10457] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hydrogen embrittlement of Ni-Ti superelastic alloy in a fluoride solution (0.2% APF) has been investigated by means of a tensile test (after immersion) and hydrogen thermal desorption analysis. Upon immersion, the tensile strength of the alloy decreased to the critical stress level of martensite transformation. Hydrogen desorption of the immersed specimens appeared with a peak at around 500 degrees C. The amount of absorbed hydrogen in the alloy ranged from 100 to 1000 mass ppm when immersed in the fluoride solution for 2 to 24 h. The immersion in the fluoride solution led to the degradation of mechanical properties due to hydrogen embrittlement. The results of the present study imply that one reason that Ti and its alloys fracture in the oral cavity is the fact that hydrogen is absorbed in a fluoride solution, such as prophylactic agents.
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Affiliation(s)
- Ken'ichi Yokoyama
- Department of Dental Engineering, School of Dentistry, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Japan.
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6081
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Hurley J, Ortega AM, Lechniak J, Gall K, Maier HJ. Structural evolution during the cycling of NiTi shape memory alloys. ACTA ACUST UNITED AC 2003. [DOI: 10.3139/146.030547] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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6082
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Shabalovskaya SA, Anderegg J, Laab F, Thiel PA, Rondelli G. Surface conditions of Nitinol wires, tubing, and as-cast alloys. The effect of chemical etching, aging in boiling water, and heat treatment. J Biomed Mater Res B Appl Biomater 2003; 65:193-203. [PMID: 12632390 DOI: 10.1002/jbm.b.10001] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The surface conditions of Nitinol wires and tubing were evaluated with the use of X-ray photoelectron spectroscopy, high-resolution Auger spectroscopy, electron backscattering, and scanning-electron microscopy. Samples were studied in the as-received state as well as after chemical etching, aging in boiling water, and heat treatment, and compared to a mechanically polished 600-grit-finish Nitinol surface treated similarly. General regularities in surface behavior induced by the examined surface treatments are similar for wires, tubing, and studied as-cast alloy, though certain differences in surface Ni concentration were observed. Nitinol wires and tubing from various suppliers demonstrated great variability in Ni surface concentration (0.5-15 at.%) and Ti/Ni ratio (0.4-35). The wires in the as-received state, with the exception of those with a black oxide originating in the processing procedure, revealed nickel and titanium on the surface in both elemental and oxidized states, indicating a nonpassive surface. Shape-setting heat treatment at 500 degrees C for 15 min resulted in tremendous increase in the surface Ni concentration and complete Ni oxidation. Preliminary chemical etching and boiling in water successfully prevented surface enrichment in Ni, initially resulting from heat treatment. A stoichiometric uniformly amorphous TiO(2) oxide generated during chemical etching and aging in boiling water was reconstructed at 700 degrees C, revealing rutile structure.
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Affiliation(s)
- S A Shabalovskaya
- Ames Laboratory, Institute for Physical Research and Technology, Iowa State University, Ames, IA 50011, USA.
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6083
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Itälä A, Välimäki VV, Kiviranta R, Ylänen HO, Hupa M, Vuorio E, Aro HT. Molecular biologic comparison of new bone formation and resorption on microrough and smooth bioactive glass microspheres. J Biomed Mater Res B Appl Biomater 2003; 65:163-70. [PMID: 12632386 DOI: 10.1002/jbm.b.10529] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In a recent in vitro study, chemical microroughening of a bioactive glass surface was shown to enhance attachment of MG-63 osteoblastic cells to glass. The current study was designed to delineate the effects of microroughening on the gene expression patterns of bone markers during osteogenesis and new bone remodeling on bioactive glass surface in vivo. With the use of a rat model of paired comparison, a portion of the medullary canal in the proximal tibia was evacuated through cortical windows and filled with microroughened or smooth bioactive glass microspheres. The primary bone-healing response and subsequent remodeling were analyzed at 1, 2, and 8 weeks, respectively, by radiography, pQCT, histomorphometry, BEI-SEM, and molecular biologic analyses. The expression of various genes for bone matrix components (type I collagen, osteocalcin, osteopontin, osteonectin) and proteolytic enzymes (cathepsin K, MMP-9) were determined by Northern analysis of the respective mRNAs. Paired comparison showed significant differences in the mRNAs levels for specific bone matrix components at 2 weeks: osteopontin was significantly higher (p =.01) and osteonectin significantly lower (p =.05) in bones filled with microroughened microspheres than in those filled with smooth microspheres. Bones filled with microrough microspheres also showed significantly increased ratios of cathepsin K and MMP-9 (both markers of osteoclastic resorption) to type I collagen (p =.02 and p =.02, respectively) at 2 weeks and a significantly increased expression of MMP-9 at 8 weeks (p =.05). The pQCT, histomorphometric, and BEI-SEM analyses revealed no significant differences in the pattern of bone-healing response. Based on these results, microroughening of a bioactive glass surface could trigger temporal changes in the expression of specific genes especially by promoting the resorption part of new bone-remodeling processes. Future studies are needed to evaluate if the observed changes of gene expression are directly related to the microrough surface of any biomaterial or are biomaterial specific.
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Affiliation(s)
- A Itälä
- Department of Surgery, University of Turku, Kiinanmyllynkatu 4-8, FIN-20520 Turku, Finland
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6084
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Zechner W, Tangl S, Fürst G, Tepper G, Thams U, Mailath G, Watzek G. Osseous healing characteristics of three different implant types. Clin Oral Implants Res 2003; 14:150-7. [PMID: 12656873 DOI: 10.1034/j.1600-0501.2003.140203.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The macroscopic and especially microscopic properties of implant surfaces play a major role in the osseous healing of dental implants. The aim of this study was to perform a histologic and histomorphometric comparison of the healing characteristics of anodically modified, machined and hydroxyapatite (HA)-coated implant types. A total of 24 machined surface implants (MSI), 24 HA-coated implants (HCI) and 24 anodized titanium surface implants (ASI) were inserted into the mandibles of 12 adult mini-pigs after extracting all mandibular premolars. Four animals each were killed after covered healing for 3, 6 and 12 weeks. Undecalcified ground sections were subjected to histologic and histomorphometric examinations. Primary effects and interactions were statistically evaluated and least square means (Tukey test) were compared. Histologic evaluations showed broad-based bone apposition to HA-coated and anodically roughened surfaces as well as narrow bone contacts to the machined surface. Localized resorption was only observed with the HA-coated implants. Overall, histomorphometric evaluation of bone-to-implant contact percentages for all observation periods showed significant differences between MSI (19.39% +/- 4.53) and HCI (39.05% +/- 4.53; P = 0.0092) and between MSI and ASI (42.72% +/- 4.20; P = 0.0011). In conclusion, the results of this study show that an anodically roughened implant may provide a similar rate of bone-to-implant contact as a HA-coated implant. In the presence of bone quality II to IV, according to Lekholm & Zarb (1985, in: Tissue-Integrated Prostheses: Osseointegration in Clinical Dentistry. Chicago: Quintessence Publishing), this may be of particular benefit, possibly because of higher stability, in maintaining pre-implantation functional strength after implant healing.
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Affiliation(s)
- Werner Zechner
- Department of Oral Surgery, Dental School of the University of Vienna, Vienna, Austria
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6085
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Abstract
Natural materials, such as wood and bone, possess structures fulfilling the requirements of support and transport of nutrients. Similarity in function and properties provides inspiration for investigating the possible use of wood as an implant material. Juniperus communis wood is dense, durable, and strong and has naturally impregnated essential oils that display antiseptic properties. This study investigated the toxicity of the oil, the effect of sterilization on the mechanical properties of the wood, and bone attachment with animal studies. The possible toxicity of the oil was determined orally and by intravenous injection. At low concentrations, the dose that would be released by the wood in the body could be tolerated without any detrimental effects. Sterilization of the wood in boiling water lowered the elastic modulus and modulus of rupture to a level at which the elastic modulus could be better matched to bone. Wood shaped into the form of femoral implants were implanted into rabbits and displayed good acceptance by the body up to a period of 3 years, indicating bone apposition, abutment into pores, and growth into drilled cavities.
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Affiliation(s)
- K A Gross
- School of Physics and Materials Engineering, P.O. Box 69M, Monash University, 3800 Australia.
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6086
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Shibata N, Tomita N, Ikeuchi K. Numerical simulations on fatigue destruction of ultra-high molecular weight polyethylene using discrete element analyses. J Biomed Mater Res A 2003; 64:570-82. [PMID: 12579572 DOI: 10.1002/jbm.a.10374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Ultra-high molecular weight polyethylene (UHMWPE) is a heterogeneous material composed of a networked substructure of grain boundary and grain aggregation. A new numerical model based on the discrete element method (DEM) was proposed to examine microscopic defect formation and propagation in UHMWPE. Numerical simulations were carried out using this model under two types of loading condition: unidirectional repetitive compression (simple loading) and bidirectional repetitive compression (switched loading). Subsurface defects were initiated and propagated in the vicinity of grain boundaries under both loading conditions. The defect propagation behavior was especially sensitive to grain boundary allocation under switched loading. An increase in defects was more rapid under switched loading than under simple loading. These numerical results showed qualitatively good agreement with experimental ones. It is suggested that the newly developed numerical method based on the DEM is a promising method to investigate fatigue behavior of a heterogeneous material such as UHMWPE under complicated loading conditions.
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Affiliation(s)
- Nobuyuki Shibata
- Department of Human Engineering, National Institute of Industrial Health, 6-21-1 Nagao, Tama-ku, Kawasaki 214-8585, Japan.
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6087
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Osano E, Kishi J, Takahashi Y. Phagocytosis of titanium particles and necrosis in TNF-alpha-resistant mouse sarcoma L929 cells. Toxicol In Vitro 2003; 17:41-7. [PMID: 12537961 DOI: 10.1016/s0887-2333(02)00127-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In the oral cavity, titanium is an excellent biocompatible material. However, it is reported that high ratios of intracellular titanium particles can cause cell apoptosis or necrosis by as-yet unknown mechanisms. The purpose of this study was to investigate the response of tumor necrosis factor alpha (TNF-alpha)-resistant L929 fibroblasts to titanium particles. Cells were cultured in Eagle's medium supplemented with fetal bovine serum and L-glutamine. Titanium particle sizes were less than 9 micro. Cytotoxicity was assayed by a cell counting kit, trypan blue dye exclusion test and lactate dehydrogenase (LDH) leakage. The production of reactive oxygen species (ROS) was detected by a confocal laser scanning microscope (CLSM) using dichlorofluorescein diacetate as a fluorescent probe. Morphology was viewed by a CLSM and with an X-ray microanalyser (XMA). When titanium particles were added to cells, the viability decreased to around 50% at a particle concentration of 2.0%. The number of dead cells and LDH activity in the culture media increased significantly between 1 and 2 days. However, formation of active oxygen species did not occur, since no dichlorofluorescein fluorescence was observed. A scanning electron photomicrograph (SEM) revealed a large number of particles covering or adhering to cellular components in lysed cells compared with flattened control cells attached to the substrate. The XMA showed that the titanium accumulation was coincident with the deformed cell shape. The CLSM also confirmed that particles were within the cells. From these results it was concluded that titanium particles ingested in large quantities into the cell induced necrosis by a pathway other than by producing ROS.
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Affiliation(s)
- E Osano
- Department of Microbiology, School of Dentistry, Aichi-Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650, Japan
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6088
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Webster TJ, Ergun C, Doremus RH, Lanford WA. Increased osteoblast adhesion on titanium-coated hydroxylapatite that forms CaTiO3. ACTA ACUST UNITED AC 2003; 67:975-80. [PMID: 14613247 DOI: 10.1002/jbm.a.10160] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
CaTiO(3) is a strong candidate to form at the interface between hydroxylapatite (HA) and titanium implants during many coating procedures. However, few studies have compared the cytocompatibility properties of CaTiO(3) to HA pertinent for bone-cell function. For this reason, the objective of the present in vitro study was to determine the ability of bone-forming cells (osteoblasts) to adhere on titanium coated with HA that resulted in the formation of CaTiO(3). To accomplish the formation of CaTiO(3), titanium was coated on HA discs and annealed either under air or a N(2)+H(2) environment. Materials were characterized by X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), and atomic force microscopy (AFM). These characterization techniques demonstrated the formation of a nanometer rough CaTiO(3) layer as a consequence of interactions between HA and titanium during coating conditions. Results from cytocompatibility tests revealed increased osteoblast adhesion on materials that contained CaTiO(3) compared to both pure HA and uncoated titanium. The greatest osteoblast adhesion was observed on titanium-coated HA annealed under air conditions. Because adhesion is a crucial prerequisite to subsequent functions of osteoblasts (such as the deposition of calcium containing mineral), the present in vitro results imply that orthopedic coatings that form CaTiO(3) could increase osseointegration with juxtaposed bone needed for increased implant efficacy.
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Affiliation(s)
- Thomas J Webster
- Department of Biomedical Engineering Purdue University, West Lafayette, Indiana 47907, USA.
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6089
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Abstract
A reaction layer forms on cast titanium alloy surfaces due to the reaction of the molten metal with the investment. This surface layer may affect the corrosion of the alloy in the oral environment. The objective of this study was to characterize the in vitro corrosion behavior of cast titanium alloys. ASTM Grade 2 CP titanium, Ti-6Al-4V, Ti-6Al-7Nb and Ti-13Nb-13Zr alloys were cast into a MgO-based investment. Experiments were performed on castings (N=4) with three surface conditions: (A) as-cast surface after sandblasting, (B) polished surface after removal of the reaction layer, and (C) sandblasted surface after removal of the reaction layer. Open-circuit potential (OCP) measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air+10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was subsequently conducted in the same medium deaerated with N(2)+10% CO(2) gas 2 h before and during the experiment. Polarization resistance (R(P)) and corrosion rate (I(CORR)) were calculated. Numerical results were subjected to nonparametric statistical analysis at alpha=0.05. The OCP stabilized for all the specimens after 6 x 10(4)s. Apparent differences in anodic polarization were observed among the different surfaces for all the metals. A passivation region followed by breakdown and repassivation were seen on specimens with surfaces A and C. An extensive passive region was observed on all the metals with surface B. The Kruskal-Wallis test showed no significant differences in OCP, R(p), I(CORR) or break down potential for each of the three surfaces among all the metals. The Mann-Whitney test showed significantly lower R(P) and higher I(CORR) values for surface C compared to the other surfaces. Results indicate that the surface condition has more effect on corrosion of these alloys than the surface reaction layer. Within the oxidation potential range of the oral cavity, all the metal/surface combinations examined showed excellent corrosion resistance.
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Affiliation(s)
- Zhuo Cai
- Baylor College of Dentistry, Texas A&M University System Health Science Center, 3302 Gaston Avenue, Dallas, TX 75246, USA.
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6090
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El Briak-BenAbdeslam H, Mochales C, Ginebra MP, Nurit J, Planell JA, Boudeville P. Dry mechanochemical synthesis of hydroxyapatites from dicalcium phosphate dihydrate and calcium oxide: A kinetic study. ACTA ACUST UNITED AC 2003; 67:927-37. [PMID: 14613241 DOI: 10.1002/jbm.a.10025] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Calcium phosphate ceramics have been used successfully as synthetic bone substitutes in orthopedics, dentistry, and maxillofacial surgery. One way of preparing these ceramics is the sintering of a calcium-deficient hydroxyapatite (CDHA), which can be obtained in different ways. Mechanochemistry is one possible means of synthesizing CDHA, with an expected molar calcium-to-phosphate (Ca/P) ratio +/- 0.005. The grinding can be carried out under dry or wet conditions. To optimize the experimental conditions of CDHA preparation by dry mechanosynthesis and for a better understanding of the DCPD/CaO mechanochemical reaction, we performed a kinetic study in which some of the experimental parameters were varied. Carried out with two different vertical rotating ball mills, this kinetic study showed that (1) experiments are reproducible and give as a final product a hydroxyapatite powder, formed of nano-sized crystals of around 20 nm, with a controlled Ca/P ratio; (2) the time for complete disappearance of DCPD and the time for complete reaction are in direct proportion to the mass of the ground powder; but (3) the time for complete disappearance of DCPD is independent of the Ca/P ratio while the time for complete reaction increases exponentially with the Ca/P ratio; and (4) the time for complete disappearance of DCPD corresponds to the time for complete reaction solely for Ca/P = 1.5. These observations suggest a reaction mechanism in two well differentiated stages: (First stage) CaO reacts with DCPD to give first an amorphous calcium phosphate (ACP) with a low Ca/P ratio that transforms into CDHA when its Ca/P ratio reaches 1.5. At the same time, CaO is hydrated into Ca(OH)(2) by the water produced by the reaction. (Second stage) If the Ca/P > 1.5 in the initial mixture, the excess Ca(OH)(2) is added to CDHA 1.5 by reacting with the HPO(4) group of CDHA until its Ca/P ratio reaches the expected value. The slower the reaction, the higher the Ca/P in the initial mixture.
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Affiliation(s)
- Hassane El Briak-BenAbdeslam
- Laboratoire de Chimie Générale et Minérale, Faculté de Pharmacie, 15 Av. Charles Flahault, BP 14 491, 34093 Montpellier Cedex 5, France
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6091
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Morejón L, Delgado JA, Davidenko N, Mendizábal E, Barbosa EH, Jasso CF. Kinetic effect of hydroxyapatite types on the polymerization of acrylic bone cements. INT J POLYM MATER PO 2003. [DOI: 10.1080/00914030304903] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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6092
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Brown TD, Stewart KJ, Nieman JC, Pedersen DR, Callaghan JJ. Local head roughening as a factor contributing to variability of total hip wear: a finite element analysis. J Biomech Eng 2002; 124:691-8. [PMID: 12596637 DOI: 10.1115/1.1517275] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Large inter-patient variability in wear rate and wear direction have been a ubiquitous attribute of total hip arthroplasty (THA) cohorts. Since patients at the high end of the wear spectrum are of particular concern for osteolysis and loosening, it is important to understand why some individuals experience wear at a rate far in excess of their cohort average. An established computational model of polyethylene wear was used to test the hypothesis that, other factors being equal, clinically typical variability in regions of localized femoral head roughening could account for much of the variability observed clinically in both wear magnitude and wear direction. The model implemented the Archard abrasive/adhesive wear relationship, which incorporates contact stress, sliding distance, and (implicitly) bearing surface tribology. Systematic trials were conducted to explore the influences of head roughening severity, roughened area size, and roughened area location. The results showed that, given the postulated wear factor elevations, head roughening variability (conservatively) typical of retrieval specimens led to approximately a 30 degrees variation in wear direction, and approximately a 7-fold variation in volumetric wear rate. Since these data show that randomness in head scratching can account for otherwise-difficult-to-explain variations in wear direction and wear rate, third-body debris may be a key factor causing excessive wear in the most problematic subset of the THA population.
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Affiliation(s)
- Thomas D Brown
- Biomechanics Laboratory, Department of Orthopaedic Surgery, 2181 Westlawn, University of Iowa, Iowa City, IA 52242, USA.
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6093
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Abstract
The management of musculoskeletal infections is an increasing challenge to clinicians. Bioimplants provide a unique system for skeletal specific drug delivery. Antibiotic-impregnated beads and spacers can be used to treat chronic osteomyelitis and deep soft-tissue infections locally with higher antibiotic concentrations, while avoiding potential systemic side effects.
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Affiliation(s)
- Jue Wang
- Department of Orthopedics and Rehabilitation, University of Texas Medical Branch, Galveston TX 77555-1115, USA
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6094
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Kusy RP, Ambrose WW, LaVanier LA, Newman JG, Whitley JQ. Analyses of rampant corrosion in stainless-steel retainers of orthodontic patients. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2002; 62:106-18. [PMID: 12124792 DOI: 10.1002/jbm.10226] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Retainers were collected from private, university, and dental labs. After viewing these corroded and control appliances using scanning electron microscopy, corroded maxillary and mandibular retainers were selected along with a control stainless-steel retainer for in-depth chemical analysis. Using electron spectroscopy for chemical analysis, monochromated Al x-rays were rastered over areas 1.5 x 0.3 mm. After survey spectra were acquired, high-resolution multiplex scans were obtained and binding energy shifts were noted. Using Auger electron spectroscopy, a spot size of approximately 30 nm was analyzed. Photos, survey scans, and depth profiles were acquired using a 3.5kV Ar(+) ion beam that was calibrated using a SiO2 standard. Via electron spectroscopy for chemical analysis, the brown stains contained Fe and Cr decomposition products in which three carbon species were present. Proteinaceous N was found as amines or amides. No Ni was present because it had solubilized. The Cr:Fe ratio indicated severe Cr depletion in the stained regions (0.2) versus the control regions (1.3). The stained regions appeared mottled, having both dark and light areas. Via AES, the dark versus light areas of the stained regions indicated that there was an absence versus a presence of both Cr and Ni. In the dark areas corrosion penetrated 700 nm; in the light areas the depth equaled 30 nm. By comparison, the passivated layer of the control retainer was 10-nm thick. After sputtering away the affected areas, all specimens had similar spectra as the control regions. The bacterial environment created the mottled appearance and induced electrochemical potential differences so that, upon reducing the passivated layer, an otherwise corrosion-resistant alloy became susceptible to rampant corrosion. An integrated biological-biomaterial model is presented for the classic case of an orthodontic acrylic-based stainless steel retainer subject to crevice corrosion.
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Affiliation(s)
- R P Kusy
- Department of Orthodontics, University of North Carolina, Building 210-H, Room 313, Chapel Hill, North Carolina 27599, USA.
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6095
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Lee BH, Do Kim Y, Shin JH, Hwan Lee K. Surface modification by alkali and heat treatments in titanium alloys. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2002; 61:466-73. [PMID: 12115472 DOI: 10.1002/jbm.10190] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Pure titanium and titanium alloys are normally used for orthopedic and dental prostheses. Nevertheless, their chemical, biological, and mechanical properties still can be improved by the development of new preparation technologies. This has been the limiting factor for these metals to show low affinity to living bone. The purpose of this study is to improve the bone-bonding ability between titanium alloys and living bone through a chemically activated process and a thermally activated one. Two kinds of titanium alloys, a newly designed Ti-In-Nb-Ta alloy and a commercially available Ti-6Al-4V ELI alloy, were used in this study. In this study, surface modification of the titanium alloys by alkali and heat treatments (AHT), alkali treated in 5.0M NaOH solution, and heat treated in vacuum furnace at 600 degrees C, is reported. After AHT, the effects of the AHT on the bone integration property were evaluated in vitro. Surface morphologies of AHT were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Chemical compositional surface changes were investigated by X-ray diffractometry (XRD), energy dispersive spectroscopy (EDS), and auger electron spectroscopy (AES). Titanium alloys with surface modification by AHT showed improved bioactive behavior, and the Ti-In-Nb-Ta alloy had better bioactivity than the Ti-6Al-4V ELI alloy in vitro.
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Affiliation(s)
- Baek-Hee Lee
- Division of Materials Science and Engineering, Hanyang University, Seoul 133-791, Korea
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6096
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Hansson KM, Tengvall P, Lundström I, Rånby M, Lindahl TL. Surface plasmon resonance and free oscillation rheometry in combination: a useful approach for studies on haemostasis and interactions between whole blood and artificial surfaces. Biosens Bioelectron 2002; 17:747-59. [PMID: 12191923 DOI: 10.1016/s0956-5663(02)00048-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In haemostatic and biomaterial research biological processes at surfaces and in the bulk phase of the surface-contacting medium are important. The present work demonstrates the usefulness of the combination of surface plasmon resonance (SPR), sensitive to changes in refractive index at surfaces, and free oscillation rheometry (FOR), sensitive to rheological properties of the bulk, for simultaneous real-time measurements on coagulation and fibrinolysis of blood plasma and coagulation of whole blood. SFLLRN stimulated coagulation of native whole blood presented a higher SPR signal with different appearance than plasma coagulation, while the FOR signals corresponding to plasma and whole blood coagulation were similar. This indicated that the SPR technique was more sensitive to cell-surface interactions than to fibrin formation in whole blood during coagulation, while the FOR technique were equally sensitive to coagulation in whole blood and plasma. Spontaneous coagulation of native whole blood in contact with methyl- and hydroxyl-terminated self-assembled monolayers (SAM) on gold and gold surfaces regenerated after coagulation were also studied. The regenerated gold surfaces displayed the shortest coagulation times, although the contact-activation of blood coagulation for these surfaces was low. The methylated and hydroxylated surfaces were comparable in terms of coagulation activation, while the hydroxylated surfaces presented FOR signals that indicated detaching of the coagulum from the surface. The combination of SPR and FOR is well suited for studies of cell- and protein-surface interactions and simultaneous bulk processes. Possible applications are investigations of blood cell defects in patients and monitoring of native whole blood interactions with artificial surfaces.
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Affiliation(s)
- Kenny M Hansson
- Department of Biomedicine and Surgery, Division of Clinical Chemistry, Linköping University Hospital, SE-581 85, Linköping, Sweden.
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6097
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Ponsonnet L, Comte V, Othmane A, Lagneau C, Charbonnier M, Lissac M, Jaffrezic N. Effect of surface topography and chemistry on adhesion, orientation and growth of fibroblasts on nickel–titanium substrates. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2002. [DOI: 10.1016/s0928-4931(02)00097-8] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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6098
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Khang G, Bang Lee H, Ho Lee J. Polymeric Biomaterials. Biomaterials 2002. [DOI: 10.1201/9781420040036.ch3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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6099
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Xie Y, Sproule T, Li Y, Powell H, Lannutti JJ, Kniss DA. Nanoscale modifications of PET polymer surfaces via oxygen-plasma discharge yield minimal changes in attachment and growth of mammalian epithelial and mesenchymal cells in vitro. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2002; 61:234-45. [PMID: 12007204 DOI: 10.1002/jbm.10141] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Surface topography is believed to be a factor affecting cellular morphology, proliferation, and differentiation. The effect of surface roughness in the micron to supramicron range has been investigated previously. In the current study, the influence of nanoscale surface roughness was examined in terms of its effects on morphology, cytoskeleton expression, proliferation, differentiation, and apoptosis of three model cell types. Polyethylene terephthalate (PET) disks were etched using oxygen plasma to produce uniform and decidedly nanoscale levels of surface roughness. Three distinct types of cell lines-mouse 3T3-L1 preadipocytes, human JEG-3 choriocarcinoma cells, and human MCF-7 breast adenocarcinoma cells-were cultured on the plasma-treated disks. Untreated PET disks were used as a control. Cytoskeletal proteins (F-actin and cytokeratin) exhibited similar patterns of expression. Cell morphology also was similar on both surfaces. Cell growth kinetics for the three types of cells and hormone secretion from the JEG-3 cells were not significantly different from that of the controls (p > 0.05). However, the differentiation of preadipocyte 3T3-L1 cells into lipid-laden fat cells was modestly affected by nanoscale surface topography. In addition, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15dPGJ(2))-induced apoptosis of the JEG-3 and MCF-7 cells revealed differences between the two surfaces. Plasma-treated surfaces showed more differentiated and apoptotic cells, respectively, compared to the controls. These results indicate that nanoscale roughness contributes in only moderate ways to cellular adhesion, proliferation, and differentiation in the cell lines tested.
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Affiliation(s)
- Yubing Xie
- Department of Obstetrics and Gynecology, Laboratory of Perinatal Research, The Ohio State University, College of Medicine and Public Health, 1654 Upham Drive, Means Hall, Columbus, Ohio 43210, USA
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6100
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Thian ES, Loh NH, Khor KA, Tor SB. Microstructures and mechanical properties of powder injection molded Ti-6Al-4V/HA powder. Biomaterials 2002; 23:2927-38. [PMID: 12069334 DOI: 10.1016/s0142-9612(01)00422-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Taguchi method with an L9 orthogonal array was employed to investigate the sintered properties of Ti-6Al-4V/HA tensile bars produced by powder injection molding. The effects of sintering factors at the 90% significance level: sintering temperature (1050 degrees C, 1100 degrees C and 1150 degrees C), heating rate (5 degrees C/min, 7.5 degrees C/min and 10 degrees C/min), holding time (30, 45 and 60 min) and cooling rate (5 degrees C/min, 20 degrees C/min and 40 degrees C/min) were investigated. Results showed that sintering temperature, heating rate and cooling rate have significant effects on sintered properties, whereas the influence of holding time was insignificant. It was found that a sintering temperature of 1100 degrees C, a heating rate of 7.5 degrees C/min and a cooling rate of 5 degrees C/min increased the relative density, Vicker's microhardness, flexural strength and flexural modulus. However, a further increment of sintering temperature to 1150 degrees C did not show any discernable improvement in the relative density and Vicker's microhardness, but there was a slight increase of 0.6% and 0.9% in the flexural strength and flexural modulus, respectively. Mechanically strong Ti-6Al-4V/HA parts with an open porosity of around 50% were developed.
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Affiliation(s)
- E S Thian
- School of Mechanical and Production Engineering, Nanyang Technological University, Singapore, Singapore
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