摘要:

AbstractThe rotating ring‐disk electrode technique has been applied to the study of anodic dissolution of dental amalgam in a simulated saline solution.The electroactive domains of the silver, tin, and mercury couples (the main constituents of the amalgam) were determined from current–potential curves obtained at a rotating gold‐disk electrode in solutions containing salts of the respective metals. Subsequently, anodic currents were applied to a rotating amalgam‐disk electrode and the soluble products produced were identified using a concentric gold ring electrode, i.e., using the rotating gold‐ring, amalgam‐disk electrode. Species generated at the amalgam disk are transferred to the gold ring by convective diffusion. Tin ions were found to be the only soluble species generated at the amalgam disk. No evidence for dissolution of other components was found. The selective dissolution of tin from the amalgam is also consistant with potential shifts observed in repetitive current‐potential curves of an amalgam disk.This study provides a direct proof for the selective dissolution of tin during corrosion of dental amalgam in anin vit

ISSN:0021-9304    

DOI:10.1002/jbm.820120102

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractPoly(methyl methacrylate) as used in polymer replica tooth implants was fabricated into 6 × 6 mm cylindrical specimens and cured in either an air oven, pressure pot, autoclave, or microwave oven. Polymer porosity was achieved by means of either (1) intrinsic foaming agents, or (2) compacting different sizes of large beads with a minimum of monomer, with dense PMMA used as a control. Specimens were then implanted in the long bones of baboons.Histology of thin‐sectioned and ground specimens from the sacrificed animals revealed complete tissue ingrowth into implanted material made of medium and large PMMA beads, very superficial ingrowth into material containing foaming agents and anorganic bone chips, and no ingrowth into dense PMMA implants.None of the implants were rejected or caused chronic inflammation. The effect on histologic response of the different curing methods could not be distinguish

ISSN:0021-9304    

DOI:10.1002/jbm.820120103

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractA carbon fiber‐reinforced carbon is being evaluated as a promising implant material. In a unidirectional composite, high strengths (1200 MN/m2longitudinal flexural strength) and high modulus (140 GN/m2flexural modulus) may be obtained with an interlaminar shear strength of 18 MN/m2. Alternatively, layers of fibers may be laid in two directions to give more isotopic properties. The compatibility of the material with bone has been studied by implanting specimens in holes drilled in rat femora. For a period of up to 8 weeks, a thin layer of fibrous tissue bridged the gap between bone and implant; but this tissue mineralizes and by 10 weeks, bone can be observed adjacent to the implant, giving firm fixation. Potential applications include endosseous dental implants where a greater strength in the neck than that provided by unreinforced carbon would be advantageou

ISSN:0021-9304    

DOI:10.1002/jbm.820120104

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractAnin vitromethod has been developed for screening of candidate biomaterials in an early phase of their development. The test is based on L‐929 mouse fibroblast cultures and their response to powdered polymer samples. It applies microscopic observation for the detection of morphological changes, uses dye exclusion testing for cell viability determination, and utilizes estimation of population doublings as an end point. The test is shown to be reliable and reproducible and is compared toin vivoimplantation studies in rats, previously reporte

ISSN:0021-9304    

DOI:10.1002/jbm.820120105

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractFluorescence labeling can be used in studying protein sorption on various surfaces with a sensitivity of about 10−8g/cm2, commensurate with radioactive labeling. Fluorescamine proved to be the most suitable compound for studying protein sorption on hydrophilic gels, because, unlike fluoresceine isothiocyanate and dansylchloride, free fluorochrome does not interfere with measurements. Sorption properties of labeled serum albumin were tested on poly(2‐hydroxyethyl methacrylate), on the copolymer of 2‐hydroxyethyl methacrylate with methyl methacrylate, and on polyethylene. Labeling does not cause aggregation of the protein, but, as expected, it shifts and somewhat broadens its electrophoretic band while at the same time slightly raising its affinity toward hydrophobic sur

ISSN:0021-9304    

DOI:10.1002/jbm.820120106

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractSurgically produced fractures of rabbit tibiae were internally stabilized with in tramedullary rods of stainless steel (316LVM), titanium (6A1,4V), polyacetal (Delrin), and polyamide (Nylon 101). Periodic radiographs were taken until sacrifice at 16 weeks after fracture. Structural properties of the tibiae were determined in torsion with the rodsin situ, and then the tissue was prepared for histology or microradiography.The results demonstrated that fracture remodeling was adversely affected by the metal rods. New bone was seen to have formed over the ends of the metal rods, and cortical bone resorption was observed in the fracture region, suggestive of transfer of mechanical stress to the rods, resulting in stress shielding of the diaphysis. Negligible osseous response to the polymeric rods was observed; fracture callus remodeling was extensive. The torsional test results demonstrated that fractures with polymeric rods were significantly stronger and tougher than those with metallic rods. With the exception of titanium, the strength of healed fractures was inversely related to the elastic moduli of the implant materials.

ISSN:0021-9304    

DOI:10.1002/jbm.820120107

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractThe purpose of this report is to present our 5‐year experience in reconstructing large bony defects in the cranial vault of 16 patients. The method employs an alloplastic implant device made of elastomer‐coated cloth mesh, used in conjunction with bone grafting [D. L. Leake and M. Habal,J. Biomed. Mater. Res.,10, 555 (1976)]. The cranial defects ranged in size from 6 × 6 cm to 15 × 17 cm. The defects were in the frontal, temporoparietal, and occipital regions. Particularly challenging was the frontal‐orbital region involving the superciliary ridges. The alloplastic implant provides controlled contour of the bone graft material while providing strength and stability during healing. The implant has adequate but not complete rigidity, allowing adaptability in the operating room. The elastomer used is a polyetherurethane. Any biocompatible cloth mesh can be used, but Dacron [poly(ethylene terephthalate)]was chosen because of its extensive implant history.Contrasted with reconstruction using only bone, where as many as half of the cases had uneveness and were found to be aesthetically unsatisfactory, the technique described here has resulted in aesthetically excellent results and an intact neurocranium in the 16 patients studied t

ISSN:0021-9304    

DOI:10.1002/jbm.820120108

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractA prosthesis based on a new concept of gleno‐humeral motion has been developed and clinically tested for the past 2 years. The “floating‐socket” total shoulder replacement contains a nondislocatable, dual spherical bearing system consisting of a small sphere within a larger sphere with their centers offset to provide the physiologic “floating fulcrum” for mechanically advantageous motion. This geometric configuration allows a prosthetic range of motion in excess of anatomical limits to allow soft tissue structures to limit motion rather than mechanical impingement. The device is constructed from Co‐Cr‐Mo alloy and RCH‐1000 polyethylene such that no metal‐metal contact can occur.Experimental results in a 112‐lb adult male chimpanzee and six clinical cases have revealed superior fixation strength of both glenoid and humeral components, as well as functional adaptation of the prosthesis without fracture of fixturing bone or p

ISSN:0021-9304    

DOI:10.1002/jbm.820120109

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractShort‐term stress relaxation of four dental amalgam alloys was studied. Test materials included two conventional lathe‐cut restoratives, a spherical alloy, and a dispersed phase product. Specimens were 24‐hr‐old 4 × 8‐mm cylinders. The specimens were compressed and held at constant strain on development of a stress (S0) of 28 MN/m2. Subsequent stress relaxation (Dt) was recorded for 60 sec. Data were obtained at eight nominal temperatures between 0 and 55°C.Over the experimental temperature range, fractional stress losses at 60 sec (Dt/S0/60) for specimens made from lathe‐cut alloys increased from 10% to 58%. The spherical material and the dispersed phase alloy showed fractional stress losses (Dt/S0/60) ranging from 9% to 47% and 9% to 31%, respectively.It would appear that particle morphology and alloy composition affect stress‐relaxation behavior of dental amalgam. Stress decay patterns enhance significantly the mechanical characterization of

ISSN:0021-9304    

DOI:10.1002/jbm.820120110

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820120111

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY