SEARCH · PubMed Health

Results for “Compressive Strength”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31Linked to original sources

PubMed1984

Effect of cement pressure and bone strength on polymethylmethacrylate fixation.

The effect of the quality of the bone and of the cement pressurization magnitude and duration on the fixation achieved with polymethylmethacrylate (PMMA) bone cement is studied in vitro. Seventy-one cement-bone interface specimens, prepared under various conditions of pressurization of low-viscosity bone cement, are tested in tension. The load at failure and the maximum cement penetration are measured to assess the fixation achieved, and the quality of the bone is assessed by determining the compressive strength of each of the bone specimens. Statistical analysis of the data indicates that the pressure magnitude is the most influential of the factors considered in the cement penetration behavior and in the development of failure load capacity. The duration of the pressure does not appear to be a significant factor. The cement penetration is a decreasing function of the bone strength, reflecting a decrease in the porosity and an increase in the area fraction. Although not directly measured in these tests, these latter bone properties are indirectly measured by the bone compressive strength. The effect of increasing bone strength on the failure load is nonlinear. The development of adequate failure load capacity is the result of a balance between the cement penetration allowed by the porosity of the bone and the inherent strength of the cancellous bone itself. Weak bone, although adequately penetrated by cement, cannot provide strong fixation. Stronger, denser bone limits cement penetration, but pressurization enhances development of failure load capacity through more complete infusion and interlocking of the cement in the available pore space. The strength of the fixation achievable for any bone is limited by the intrinsic strength of the bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗

PubMed1983

Strain-rate dependence of the compressive properties of normal and carbon-fiber-reinforced bone cement.

Normal and carbon-fiber-reinforced (1 wt. %) bone cement samples were tested in compression at various strain rates. Both the compressive strength and proportional limit increased in general with increasing strain rate. Similar strain-rate sensitivity was also shown by the carbon-fiber-reinforced bone cement. The mechanical properties, namely the modulus of elasticity, the proportional limit, and the compressive strength of the carbon-fiber-reinforced bone cement showed highly significant positive correlations with the strain rate.

Bone Cements↗

PubMed2003

Propagation of surface fissures in articular cartilage in response to cyclic loading in vitro.

BACKGROUND: Mechanical overloading of synovial joints can damage the articular cartilage surface and may lead to osteoarthritis. However, causal links between mechanical and biological events in cartilage are poorly understood. OBJECTIVES: To test the hypothesis that surface fissures in cartilage can propagate mechanically if the joint surface is subjected to vigorous cyclic loading. METHODS: Thirty-five cartilage-on-bone specimens, 15-mm square, were removed from mature bovine knee and shoulder joints. Specimens were loaded by means of a 9-mm-diameter flat indenter with a beveled edge, and their compressive strength determined. Failure occurred in the cartilage surface at an average stress of 36 MPa. Cartilage fissures were marked with Indian ink, photographed, and their length and width measured using image analysis software. Each damaged specimen was subjected to cyclic loading at 40% of its compressive strength, at 0.5 Hz, for up to 5 h. Fissure length and width were measured at regular intervals. After testing, fissure depth was measured from histological sections, and compared with measurements from damaged cartilage which was not cyclically loaded. RESULTS: Cyclic loading caused cartilage fissures to increase in length (mean 353%, P<0.01) and width (360%, P<0.01) but not depth. Propagation was rapid at first, but approached equilibrium after several hundred cycles. Rehydration in saline had no effect on fissure length, but width returned to pre-cyclic loading values. CONCLUSION: Cartilage fissures can propagate mechanically when a joint surface is subjected to cyclic compressive loading in vitro. The transient opening-up of fissures to form wide surface "wounds" during cyclic loading could be of biological significance if it occurred in living people. RELEVANCE: In living joints, wide open fissures in the cartilage surface could promote degenerative changes in the tissue.

Animals↗

PubMed2006

Utilization of municipal solid waste bottom ash and recycled aggregate in concrete.

In the combustion process of municipal solid waste (MSW), bottom ash (BA) represents the major portion of the solid residue. Since BA is composed of oxides, especially SiO(2) and CaO, the feasibility of its application in concrete as a substitute for cement was tested. It was found that at the age of 28 days, the flexural and compressive strengths of the binder linearly decrease at the rate of 0.03 and 0.02 MPa per wt% of BA in the binder, respectively. According to the results it may be recommended to replace up to 15 wt% of cement by BA and to use such binder where a low strength of concrete elements is required. Furthermore, the aggregate used for low strength concrete need not be of a very good quality. Therefore, gravel aggregate was partially replaced by recycled aggregate (RA). Consistency measured by slump was significantly reduced (>50%) when BA or/and RA were introduced into the mixture. However, concrete density and compressive strength were not affected and were approximately 2300 kg/m(3) and approximately 40 MPa, respectively.

Calcium Compounds↗

PubMedDate not supplied

A simplified method of opacifying and mixing acrylic cement for percutaneous vertebroplasty: a clinical and in vitro study.

The objective of this study was to simplify the opacifying mixing process of the bone cement and contrast used for percutaneous vertebroplasty (PVP). We performed a biomechanical study of polymethyl methacrylate (PMMA) (Corinplast 3) using three different mixtures of PMMA, monomer, and contrast: group I, 2:1; group II, 3:2; group III, 3:2:1 ratio of powder/monomer/iodinated contrast (Omnipaque). In vitro biomechanical testing of ultimate compressive strength was carried out in all samples. Following the conclusion of a proper bone cement mixture regimen drawn from the in vitro study, PVP was performed in 125 patients: 58 with cancer, 12 with hemangioma, and 54 with osteoporotic fracture. The ultimate compressive strength in group III was decreased by 38% compared to groups II and I. Proper fluoroscopic visualization was achieved in all PVP procedures using this mixture. There were no major complications associated with injection of the cement mixture. Complete (CR) and partial response (PR) was obtained in 64% and 32.8%, respectively. No further vertebral collapse occurred during follow-up. The regimen using iodinated contrast for cement visualization during PVP provides a simple and convenient new method for mixing. Although the biomechanical strength is altered by the contrast medium added, it seems insignificant in clinical practice based on the authors' limited experience.

Adolescent↗

PubMed1993

Osteoinductive, morphologic, and biomechanical properties of autolyzed, antigen-extracted, allogeneic human bone.

Autolyzed, antigen-extracted, allogeneic (AAA) bone was prepared from human cortical bone and its morphologic, biomechanical, and osteoinductive properties were compared with untreated (frozen) as well as lyophilized human bone. Scanning electron microscopy revealed removal of inorganic calcium phosphates and persistence of shrunken collagen fibrils on the surface of AAA bone matrix. Biomechanical testing of differently prepared bone samples showed that lyophilization increased both the modulus of elasticity (P < .00001) and the compressive strength (P < .00001). Depending on the depth of decalcification in the preparation of AAA bone, both measured values decreased in rehydrated AAA bone compared with untreated bone (P < .00001). Completely demineralized and rehydrated AAA bone was soft, flexible, and showed very little compressive strength. Differences in biomechanical behavior between samples drilled longitudinally or perpendicularly to the diaphyseal bone axis were observed. Xenogeneic human bone samples were implanted in muscle pouches of Sprague-Dawley rats for 6 weeks. AAA bone implants showed chondrogenesis and osteogenesis in 50% of the cases, while untreated or lyophilized bone implants induced no new cartilage or bone formation. As decalcification exposed xenogeneic organic matrix components, AAA bone implants provoked the highest inflammatory reaction. When AAA bone samples were implanted in immunosuppressed rats, the inflammatory reaction was suppressed and 94% of the implants showed endochondral bone formation. The chondroinductivity of the bone samples also was tested in vitro using neonatal rat muscle tissue to avoid interference with inflammatory cells and secreted cytokines. In this assay, 68% of AAA bone samples induced chondroneogenesis, while untreated as well as lyophilized bone samples failed to induce any cartilage formation. The results clearly demonstrate that AAA bone has osteoinductive properties. Biomechanical stability of AAA bone implants depends on the degree of demineralization. Thus, they can be prepared in an appropriate manner for different indications in oral and maxillofacial surgery.

Animals↗

PubMed2006

Mechanical effects of the use of vancomycin and meropenem in acrylic bone cement.

BACKGROUND: The increasing resistance of certain bacteria to antibiotics commonly used in bone cements has led to a demand for alternative antibacterial agents. The antibiotics added to bone cements may, however, have detrimental effects on the mechanical properties of the cement. MATERIAL AND METHODS: We evaluated the mechanical effects of adding vancomycin and meropenem to bone cement by compression, bending and fatigue tests. RESULTS: Addition of vancomycin at a concentration of up to 2.5% (w/w) had no effect on the compressive strength. Bending and fatigue strength were negatively affected by vancomycin but not by meropenem. INTERPRETATION: A cement containing 1.25% vancomycin and 1.25% meropenem might be an interesting compromise between the introduction of antibacterial properties and preservation of the mechanical properties. With this concentration of additives the compressive strength and the fatigue strength remain unchanged, while the bending strength (-14%) and the bending modulus (-9%) are only slightly reduced and remain above the limits set by the ISO5833 standard.

Anti-Bacterial Agents↗

PubMed2002

Characterisation and treatment of roads covered with zinc ashes, muffle furnace fragments and lead slags from former non-ferrous metal industries in Belgium.

Zinc ashes, muffle furnace fragments and lead slags from non-ferrous industries were applied to pave roads in the North of Belgium. From an inventory it appeared that there are at least 490 km of such roads. In our survey the materials on these roads were characterised. The total metal concentration, the availability and the leaching as a function of time were determined. It appeared that these materials contain high concentrations of heavy metals, some of which are readily available. The high leaching of some metals makes them as such unsuitable as secondary construction material. Methods for the application of these materials for road construction were examined where the materials replaced part of the sand and gravel fraction in lean concrete and in bituminous mixtures, or where they replaced the sand in sand-cement mixtures, all these to be used for road foundations, cycle tracks, etc. When lead slags were applied in lean concrete, a material was obtained complying with the standards for secondary construction materials and with sufficient compressive strength for road foundations. When zinc ashes or muffle fragments were used to replace sand in sand-cement mixtures, again a suitable construction material was obtained. The other combinations tried out were rather unsuccessful, because of high metal leaching and/or poor compressive strength.

Belgium↗

PubMed1984

Distribution of mechanical robustness in the human femoral shaft.

The object of the present study was to determine the mechanical robustness of the human femoral shaft. The geometric properties of the cross sections were measured. The compressive strength, the gamma-ray absorption, and the ash density of the compact bone were examined at 40 points along the shaft. The geometric properties connected with the mechanical robustness increased with the body size. The distribution of the mineral density, the material compressive strength, and the endurable bending moment on the surface of the bone were determined. The density and the strength were great in specimens from the postero-lateral side and in those from the antero-medial to the postero-medial side of the shaft. The calculated endurable bending moment was large on the anterior, the postero-lateral, and the postero-medial surfaces of the middle part of the bone. The anterior side was especially able to endure a large bending moment when the bone had a large moment of inertia of the cross-sectional area in the sagittal direction. The distribution of these mechanical properties could be the functional adaptation of the human femur against external bending forces mainly caused by muscle activity.

Aged↗

PubMed1992

A classification of dental composites according to their morphological and mechanical characteristics.

The on-going search for a biologically acceptable restorative material has brought a confusing variety of composites on the dental market. In the present study, commercially available composites are categorized as a function of their mean particle size, filler distribution, filler content, Young's modulus, surface roughness, compressive strength, surface hardness, and filler morphology. Out of this information, it can be concluded that the materials of choice for restoring posterior cavities at present are the Ultrafine Compact-Filled Composites because their intrinsic surface roughness, Young's modulus and, indirectly, their filler content, compressive strength, and surface hardness are comparable to the same properties of enamel and dentin. The Ultrafine Midway-Filled Composites seem to be very satisfactory materials for anterior use.

Composite Resins↗

PubMed2004

[Effect of jiangu granule on quality of bone in model rats with osteoporosis induced by ovariectomy].

OBJECTIVE: To study the effect of Jiangu granule (JGG) on quality of bone in model rats with osteoporosis. METHODS: Osteoporosis model was established by means of ovariectomy. Bone mineral density (BMD) was measured with dual energy X-ray densitometry. Osseous tissue structure of upper tibia was observed by ono-decalcified section and toluidine blue staining, and morphometry was carried out. Compressive strength limit and elastic modulus of first lumbar vertebrae, and bend load of femur were measured by light-based elastometer. RESULTS: JGG can significantly increase BMD, area of trabecula and thickness of bone cortex/diameter of marrow cavity ratio of model rats, to elevate the compressive strength limit of vertebrae and bend load of femur. CONCLUSION: JGG could increase BMD of osteoporosis model rats, and also could effectively improve the structure of osseous tissue, biomechanical property of bone and enhance the overall quality of bone.

Absorptiometry, Photon↗

PubMed1996

Method for enhancing the fluoride release of a glass-ionomer cement.

The cariostatic action of the glass-ionomer cement has been attributed to its sustained release of fluoride. The fluoride in the set cement originates from the glass particles which are eroded, in part, during the setting reaction. In this study a water-activated glass-ionomer was mixed with sodium fluoride (NaF) solutions of different concentrations (0%, 2% and 4%). The different cements were used to prepare discs which were stored individually in demineralized water at 37 degrees C, the fluoride concentration of the storage solutions were measured, at intervals, until the specimens were 80 days old. The effect of the different mixing solutions on the working and setting times and compressive strength were also determined. It was found that the cement mixed with the 4% solution of NaF released significantly more fluoride than the water mixed control. The fluoride solution mixed materials had longer setting times than the control, but there was no significant difference in the compressive strengths. All the materials became progressively stronger on storage. Mixing the cement with a 4% solution of NaF increased the initial fluoride release of the glass-ionomer without seriously affecting other physical properties.

Delayed-Action Preparations↗

PubMed2001

Influence of mixing techniques on the physical properties of acrylic bone cement.

Palacos R bone cement was prepared using three commercially available mixing techniques, first generation, second generation and third generation, to determine the mechanical properties and porosity contents of the bone cement. The compressive strengths, bending strengths and flexural moduli were expressed as a function of void content. The volume of pores within the cement structure was found to be a contributing factor to the physical properties of acrylic bone cement. The lower the volume of voids in the cement the better the compressive and flexural properties, hence stronger bone cement. It was found that the best results were obtained from cement that had been mixed using the Mitab Optivac or Summit HiVac Syringe systems at a reduced pressure level of between -72 and -86 kPa below atmospheric pressure, resulting in cement of porosity 1.44-3.17%; compressive strength 74-81 MPa; flexural modulus 2.54-2.60 GPa; and flexural strength 65-73 MPa.

Acrylates↗

PubMed1994

Sodium fluoride sustained-release bone cement: an experimental study in vitro and in vivo.

A new "low temperature" bone cement, consisting of polymethylmethacrylate (PMMA) and 6% sodium fluoride, was developed for use in orthopedics. Fluoride is a well-known agent that may stimulate osteoblast activity and differentiation in vitro and in vivo; for this reason fluoride has been used for 30 years in the treatment of osteoporotic diseases of the bone. A local effect obtained with a slow release of fluoride from bone cement at the interface between bone and prosthetic implants could potentially enhance new bone formation around the prosthesis. This material was investigated both "in vitro", by establishing the kinetics of fluoride release from the acrylic bone cement and its maximal compressive strength, and "in vivo", by fitting 24 rabbits, which were then killed after 4, 12 and 16 weeks, with femoral implants, following labelling with fluorescent stains to allow the histologic evaluation of bone remodelling. The "in vitro" study revealed the release kinetics of fluoride from bone cement and the compressive strength of PMMA, that is not affected by the addition of fluoride. The "in vivo" investigation showed considerable healing ability after surgical and heat trauma, and new bone formation that appears larger on the surface in contact with fluoridated cement.

Animals↗

PubMed2003

Restoration of large bone defects using a hard-setting, injectable putty containing demineralized bone particles compared to cancellous autograft bone.

An injectable, hard-setting, calcium sulfate-based putty containing demineralized bone matrix particles (AlloMatrix II, Wright Medical Technology, Inc, Arlington, Tenn) was compared to autogenous cancellous bone graft to evaluate healing in a canine model. Area fraction of new bone, modulus of elasticity, and compressive strength of new bone were evaluated, as was radiographic and histologic healing. Bilateral defects were created in the proximal humeri, and each defect was implanted with either the putty or autogenous bone according to a randomized schedule. Dogs were euthanized at 6, 13, and 26 weeks. The area fraction, modulus of elasticity, and compressive strength of newly formed bone was not significantly different between the putty and autogenous bone at 6, 13, or 26 weeks. The putty had excellent handling characteristics, was biocompatible, and was as effective as autograft bone in achieving near complete bony restoration of a large, critical-sized defect.

Animals↗

PubMed2003

[In vitro degradation and subsequent biomechanical changes of poly(lactide-co-glycolide) scaffolds prepared by mild heating under high pressure].

OBJECTIVE: To study the changes in biomechanics and such indices as intrinsic viscosity poly (lactide-co-glycolide) (PLGA) scaffolds produced by mild heating under high pressure after in vitro degradation. METHODS: PLGA scaffolds with the porosity of 90.0% and 92.5% respectively were immerged in 37 degrees Celsius; saline for 8 weeks, and the changes in their mass, intrinsic viscosity and loss of compressive strength were assessed on a weekly basis, and the acidity of the degradation solution was also measured regularly. RESULTS: Significant differences was noted in the mass reduction between the scaffolds, and the intrinsic viscosity began to decrease in both groups in the first week to half of the original value till the sixth week. A 50% reduction in the compressive strength of the scaffolds occurred at the fourth week, and till the eighth week, obvious structural collapse was observed. Along with the changes, the acidity of the degradation solution increased from 6.0 to 6.5, and the solution of 90.0% porosity group had lower pH value during the first 4 weeks than 92.5% porosity group, but such difference was no longer seen afterwards. CONCLUSIONS: PLGA scaffolds made by mild heating under high pressure have stable biomechanical performance with the half-life of approximately 6 weeks, which can be applicable for tissue engineering.

Biomechanical Phenomena↗

PubMed1999

Histological and biomechanical studies of two bone colonizable cements in rabbits.

We have developed two colonizable bone cements: the first is a partially resorbable bisphenol-alpha-glycidyl methacrylate (Bis-GMA)-based cement (PRC) and the second is a calcium phosphate cement (CPC). PRC is composed of aluminous silanized ceramic and particles of a bioresorbable polymer embedded in a matrix of Bis-GMA. CPC consisted of tricalcium phosphate, monocalcium phosphate monohydrate, dicalcium phosphate dihydrate, and xanthane. Both cements were implanted into cavities drilled in rabbit femoral and tibial condyles. After 2, 4, 12, and 24 weeks of implantation, histological observations and biomechanical tests were performed. With CPC, a progressive osteointegration with a concomitant biodegradation in the presence of macrophages were observed. The mechanical study revealed a decrease of the compressive strength until the 4th week, followed by a slight increase. There was a general decrease in the elastic modulus with time. Moreover, by week 4, the histological study showed that the new bone was in direct contact with CPC margins. No inflammation was observed during the observation period. With PRC, the osteointegration as well as the biodegradation were slight, but its compressive strength was higher than that of cancellous bone and CPC (p < 0.05) at all observation periods. Its elastic modulus was greater than that of cancellous bone and CPC until the 4th week, then fell under the values of the cancellous bone.

Animals↗

PubMed2001

Effect of mechanical grinding of MCPM and CaO mixtures on their composition and on the mechanical properties of the resulting self-setting hydraulic calcium phosphate cements.

Calcium bis-dihydrogenophosphate monohydrate (or monocalcium phosphate monohydrate, MCPM) is often used as the acid calcium phosphate in hydraulic calcium phosphate cement formulations. But commercial MCPM is not pure; it contains a small amount of orthophosphoric acid and moisture. Consequently, MCPM is difficult to mill and the powder is sticky and presents aggregates. Because granularity influences the mechanical properties of the hardened cements, a possible way to get around this difficulty that has been proposed is to premix it with other materials before grinding. We therefore ground commercial MCPM with CaO. A rapid decrease in the amount of MCPM was observed during mechanical grinding by a solid-solid reaction with calcium oxide. The final products were anhydrous or dihydrate dicalcium phosphate and/or hydroxyapatite or calcium-deficient hydroxyapatite depending on the initial calcium-to-phosphate (Ca/P) ratio. The mechanical properties (compressive strength and setting time) of cements made from MCPM and CaO were affected whatever the Ca/P ratio as a consequence of the change in composition of the starting materials. Storage at different temperatures of MCPM and CaO mixtures manually ground in a mortar for only 2 min and without mechanical grinding did not affect their composition, but a decrease was observed in the compressive strength of cements made from these mixtures.

Journal Article↗