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PubMed1989

[Quantitative analysis of sulphur in the liquid of some dental cements].

The ceramometal restoration with porcelain margin have been clinically applied to provide accuracy and esthetics. But, we experienced the cases that the color of the labial marginal area of ceramometal restoration turned dark. Then, the crown was removed and observed. And it was found that the cement color had been changed black. As the result of the ultimate analysis of this cement by means of X ray microanalyzer, some elements; Al, P, S, Ca, Ni and Zn, were detected. As the inclusion of sulphur in commercially available cements was suspected the quantitative analysis of sulphur in the liquid of glass ionomer cement and polycarboxylate cement were done by means of inductively coupled plasma spectrometer. And following results were obtained that sulphur was included 5437 micrograms/ml in the liquid of glass ionomer cement, and 2147 micrograms/ml in the liquid of polycarboxylate cement, respectively. From the above, it is suspected that sulphur reacts on dental metal and causes tooth and gingival discoloration.

Dental Cements↗
PubMed1989

[Effect of vibration for the rheology of some luting cements].

Vibrant load is known to be effective to thin the film thickness of various luting cements. In this study, a vibrator which can change various conditions such as frequency, form of wave were made, and the changes of viscosity, film thickness and bond strength were tested statistically. Furthermore, the most effective condition for the slurry of some luting cements (i.e. domestic two zinc phosphate cements, one polycarboxylate cement and one glass ionomer cement) were investigated. The results obtained were as follows. 1) When vibrant load was applied to the slurry of cement in the setting process, the rise in viscosity was apt to be slower than the same case of static load. 2) The effect of vibration appears in the early sixty seconds especially, and the effect varied with the kind of cement, frequency or form of wave. 3) Vibration was also effective for the increase of compressive strength and of bond strength.

Dental Cements↗
PubMed1989

[Morphologic studies of asbestos-cement surfaces].

A scanning electron microscopic procedure was used for the investigation of asbestos-cement surfaces. The samples of uncoated asbestos-cement sheets were up to 50 years old, coated asbestos-cement materials were 16 years old in maximum. Our results demonstrate that suitable coating systems effectively protect the asbestos-cement surface. On the other hand uncoated asbestos-cement shows a release of asbestos fibres locked up in cement. Therefore uncoated asbestos-cement sheets are emission sources of asbestos fibres. Wether the weathered material coursed a increase of asbestos fibre concentration in ambient air will be a subject of further investigations.

Asbestos↗
PubMed1988

Release of gentamicin from acrylic bone cement. Elution and diffusion studies.

It has been generally assumed that release of antibiotic from methylmethacrylate occurs either from the surface, through pores in the matrix of the cement, or by diffusion through the matrix. In vitro and in vivo studies of the release of antibiotic from cement have produced variable and inconsistent results. In our laboratory, preliminary observations suggested that antibiotic is released from methylmethacrylate by flow through an interconnecting series of voids and cracks in the cement, rather than through diffusion after having been homogeneously distributed throughout the cement. Therefore, experiments were performed to answer the fundamental question of whether the matrix of methylmethacrylate bone cement is permeable to gentamicin. In vivo elution studies were performed on injection-molded rods of methylmethacrylate that had been loaded with two different amounts of gentamicin. The first group of rods contained 0.5 gram of gentamicin for each packet and the second, 1.5 grams for each packet. The rods were embedded subcutaneously in the subcostal region of sheep for three months. Bioassay of sections of the rods, using the tube-diffusion technique of Mitchison and Spicer, showed that the more highly loaded cement had released a significantly greater proportion of gentamicin. This occurred because the more highly loaded cement contained a greater number of defects that contained gentamicin (filled voids and interconnecting cracks). In vitro diffusion studies were also performed, using 0.8-millimeter-thick disks of methylmethacrylate that did not contain antibiotic. Test solutions of either gentamicin or methylene blue were placed in the inner compartments of diffusion chambers. The outer compartments contained tissue-culture medium 199, which was sampled monthly and assayed for gentamicin or methylene blue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Induction and characterization of an interface tissue by implantation of methylmethacrylate cement into the posterior part of the cervical spine of the dog.

After the implantation of methylmethacrylate cement into the posterior part of the cervical spine of the dog, a thick layer of connective tissue forms at the bone-cement interface. The tissue is six to eight millimeters thick and in all animals it surrounds the dorsal and lateral aspects of the masses of implanted cement, grows between the undersurface of the cement and the bone of the posterior elements, and completely covers that bone. This tissue was examined by light and electron microscopy and its collagenous components were extracted and analyzed biochemically by gel electrophoresis. Specific extracellular matrix proteins in the tissue at the bone-cement interface were also localized by immunohistochemistry. The tissue at the host-cement interface contained zones of fibrocytes and plump and teardrop-shaped cells within a collagenous matrix. Type-I, Type-III, and Type-V collagen were extracted and were identified by gel electrophoresis. Type-V collagen and fibronectin were localized predominantly around the plump and teardrop-shaped cells. Type-IV collagen and laminin were localized predominantly in an area just beneath the teardrop-shaped cells at the surface of the tissue overlying the cement, suggesting that a basement-membrane-like tissue had formed in this area.

Animals↗
PubMed1986

Bone-cement interface: a histological study of aseptic loosening in twelve prosthetic implants.

The histology of bone-cement interfaces was studied by using new fixation techniques that preserve the cement, as well as sectioning the samples without decalcification. This permits histological study of the unaltered morphology, and the precise topographical distribution of fibrous tissue, bone necrosis and cellular anomalies in relation to the cement. Twelve cases of implant loosening over an average 7 year follow-up period were examined. By dynamic studies with sequential fluorescent bone labelling it was possible to evaluate precisely the extent of bone damage after the application of cement. The characteristic findings were: fibrous tissue at the bone-cement interface; bone necrosis or reduced remodelling in proximity to the cement; away from the cement, normal bone remodelling is clearly demonstrated by fluorescent labelling.

Bone Cements↗
PubMed1987

[Experiences, requirements and development of cement-free hip endoprostheses].

The main problem with endoprostheses, particularly the cementless type, is the transmission of stress from the implant to the bones and vice versa. Cement is a very good solution--at least on a short-term basis. However, the major aim in using cementless endoprostheses is to improve the long-term results as compared with those obtained when using cement. To date, this has not been possible either with more modern cementing techniques (pressurization) or with cementless endoprostheses based on the principle of bony ingrowth. The differences between cementless endoprostheses and those using cement are: the design, the nature of the implant surface, and the operative technique. Experience has shown that histologically, radiologically, and clinically (although not long-term), the results with cement-fixed acetabula are better than those with cementless prostheses. Cement-free shaft endoprostheses, on the other hand, have not yet achieved the consistently good results obtained in the femur shaft by means of pressurization. Under normal circumstances, use of a cementless acetabulum and a cement-fixed shaft is the procedure of choice. In patients under 60 years of age who are still active, as well as in repeat-arthroplasties involving substantial loss of bone, the completely cementless endoprosthesis is indicated.

Biomechanical Phenomena↗
PubMed1982

Strength of the cement-bone interface.

The fixation of total joint components to bone using acrylic bone cement is by the penetration of the cement into the microstructure of cancellous bone to achieve a mechanical interlock. It has been shown that the method of cement application and the preparation of the cancellous surface significantly affects both the tensile and shear strengths of the cement-bone interface. Doughy cement finger-packed on an uncleaned surface resulted in a very low interface strength compared to a low-viscosity cement made to penetrate a cleaned bone surface. Maximum strengths were achieved for cancellous bone cleaned by using either a high-intensity water lavage or a polyethylene brush and by facilitating penetration of the cement for distances of 5 to 10 mm into the bone.

Biomechanical Phenomena↗
PubMedDate not supplied

The effect of femoral stem cross-sectional geometry on cement stresses in total hip reconstruction.

A three-dimensional numerical stress analysis of a prosthesis-cement-proximal femur system was performed to reveal functional differences of total hip femoral component stems with varying cross-sectional shapes. The analysis was performed on stem cross-section shapes similar to many of the variations presently available in femoral components. The results indicate that the predicted levels of stress in the cement are often close to critical (i.e., failure) levels. The magnitude and mode (i.e., compression versus tension) of loading in the cement are significantly affected by the stem cross-sectional shape. Particular attention is paid to the stress in the cement within the proximal portion of the structure. High compression stresses in the cement are shown to result from prostheses with narrow medial surfaces and small area moments of inertia. High cement tensile stresses result from prostheses with small area moments of inertia. A large region of cement compression results from prosthesis cross-sections with relatively large anterior-posterior dimensions about their lateral aspect. Desirable stress distributions result from prostheses with broad medial surfaces and even broader lateral surfaces.

Biomechanical Phenomena↗
PubMed1980

Device and method for controlling cement thickness.

The ideal thickness of cement between the prosthesis and bone has not been accurately determined, but there is general agreement that the surgeon should be able to provide and accurately produce a certain thickness of cement between the prosthesis and the bone. Conventional cementing technique could allow the surgeon to ovepush the cup into direct contact with the bone producing a very thin cement coat or a void. We have developed a simple method of achieving a predictable thickness. We insert small spacers made of methylmethacrylate, which can be placed between the bone of the acetabulum and the acetabular component, preventing voids or thin areas in the cement coat. The device has been used in over 50 patients and has proven to be a simple and reliable method of allowing the surgeon to produce a predictable thickness of cement surrounding a joint replacement component. An additional benefit obtained from the use of these spacers is the ability to rigidly hold the acetabular component during polymerization of the acrylic without fear of overpushing. This allows better packing of the bone cement and prevents imperfections caused by the cup contacting the bone.

Acetabulum↗
PubMedDate not supplied

Antibacterial action of dental cements: an in vitro study.

The antibacterial activity of seven commercially available dental cements (Eugespad, Dentical, Dycal, Expaliner, PR. Scell, PR. Base Cement, PR. Lining Cement) against 1) bacterial species implicated in carious lesions or in dental plaque (Actinomyces israelii ATCC 10048, Actinomyces viscosus ATCC 19246, Streptococcus mutans ATCC 25175, Streptococcus sanguis ATCC 10557) and 2) bacterial samples of stimulated saliva was studied, in vitro, using a modification of the method of McComb and Ericson (1987). Dycal and Expaliner did not affect bacteria whereas the other dental cements displayed some antibacterial properties. Eugespad was the most active followed by PR. Base Cement + PR. Scell + Dentical and by PR. Lining Cement. Associated with mechanical and biocompatibility properties, these differences could be taken into account when choosing a dental cement for clinical use.

Actinomyces↗
PubMed1995

Primary cemented total hip arthroplasty: five to twelve year clinical and radiographic follow-up.

A retrospective clinical and roentgenographic study was completed on 131 primary cemented total hip arthroplasties with a minimum of five years follow-up (mean, seven years; range, five to twelve years). Second generation cement technique including plugging of the medullary canal, cement gun filling, and pressurization of the canal was used. Acetabular cement was also pressurized. The total mechanical failure rate of the acetabular components was 18.4% compared to that of the femoral components which was 3.1%. There was a significantly higher incidence of acetabular component failure in rheumatoid arthritis patients (38.9%) compared to a preoperative diagnosis of primary osteoarthritis (14.1%) (p = 0.013). Yet there were no rheumatoid arthritis patients in the femoral component revision group. There were no differences in revision rates for metal-backed versus nonmetal-backed cups (p = 0.113). The average thickness of the proximal medial cement mantle was 2.8 millimeters in the loosening group and 5.4 millimeters in the nonloosening group (p = 0.333). All failures occurred in those patients whose proximal medial cement mantle was less than five millimeters. The authors strongly endorse the use of hybrid total hip arthroplasty and emphasize the need for meticulous surgical technique especially in obtaining a cement mantle of sufficient thickness in the proximal medial aspect of the femur.

Adult↗
PubMed1995

Methotrexate loaded acrylic cement in the management of skeletal metastases. Biomechanical, biological, and systemic effect.

Skeletal metastases occur commonly, and frequently are complicated by the development of an impending or pathologic fracture. In the majority of instances, these patients are best treated by internal stabilization, frequently supplemented by methylmethacrylate, to relieve pain and maintain the patient's mobility. The underlying tumor may continue to grow, and if this occurs the progressive lysis may result in loosening and subsequent failure of the implant. To prevent additional local growth, postoperative radiotherapy is recommended, and many patients also receive endocrine or chemotherapy, but the adjuvant therapy is not always successful in preventing progressive local tumor induced osteolysis. It is possible that the addition of chemotherapeutic agents to the methylmethacrylate may inhibit local growth. This study was performed to determine the biomechanical, biologic, and systemic effects of adding methotrexate to methylmethacrylate. The results show that the addition of methotrexate in as much as a concentration of 2 g methotrexate per 40 g cement did not significantly alter the biomechanical characteristics of the bone cement. The incorporated methotrexate was released continuously from the loaded bone cement, and in the amount and concentration used did not have any toxic effects on the host animal. The methotrexate did not appear to be affected by the heat of polymerization and had a significant systemic effect. There was a significant reduction in pulmonary metastases with methotrexate loaded cement as compared with unloaded cement, the effect being dependent on the concentration of methotrexate in the cement. The results of these studies indicate that methotrexate loaded cement may have an important role to play as part of the orthopaedic management of impending and pathologic fractures.

Animals↗
PubMed1995

Custom-made molds that prevent cement extrusion through bone defects.

The success of a hip arthroplasty using a cemented femoral component relies in part on the quality of the cement technique, and is enhanced by obtaining a uniform, well-pressurized cement mantle around the prosthesis. For that reason, cortical bone defects in the femur pose technical difficulties for the surgeon planning a cemented femoral component. In this article, a new technique is presented that is used to prevent cement extrusion through defects in the femoral cortex when pressurizing the cement mantle around the prosthesis. Custom-molded polymethylmethacrylate (bone cement) plugs may be fashioned during operation to fill temporarily defects of almost any size.

Bone Cements↗
PubMed1995

The case for cementing all femoral components in total hip replacement.

Two important new observations underlie the recommendation that it is advisable to cement all femoral components of total hip replacement (THR). First, it is now clear that improved cementing techniques have remarkably extended the durability of the cemented fermoral fixation and markedly reduced the incidence of lysis. Second, the incidence of femoral lysis around all noncemented femoral components that have been reported with minimum 5-year follow-up is high, increasing and alarming. With good cementing in primary THR, the incidence of femoral revision for aseptic loosening at 15 to 18 years after the initial operation is only 2% to 3%, even in those 50 years of age and younger. Moreover, lysis is rare. Similarly, with improved femoral cementing, femoral revision is also far more effective. The juxtaposition of the excellent results with improved cementing and the high and rising lysis rates around noncemented femoral components clearly mandate the use of contemporary cementing procedures for all femoral components, regardless of the age or sex of the patient, the diagnosis and whether the procedure is a primary or revision one.

Bone Cements↗
PubMed1993

Bond strength of resin cements to microfilled composites.

The in vitro bond strengths of three resin cements and a light-cured and a laboratory-processed micro-filled composite were measured. Effects of two surface treatments, and three bond enhancers were analyzed. Resin cements were bonded to sandblasted composite substrates, stored at 37 degrees C in 100% humidity overnight, and debonded in tension. An analysis of variance revealed significant differences among bond strengths. Overall, the composite substrate had the largest effect on bond strength, followed by bond enhancer, cement and, finally, surface treatment. Mean bond strengths ranged from 0.9 to 13.6 MPa. A combination of Concept, Dual Cement, phosphoric acid and Silane produced the lowest mean bond strength (0.9 MPa), while EOS, Dual Cement, hydrofluoric acid, and Heliobond produced the highest recorded mean bond strength (13.6 MPa). In general, the highest bonds were produced using the light-cured composite (EOS), the acrylic monomer (Special Bond II) or the dimethacrylate monomer (Heliobond), the adhesive cement (CR Inlay Cement), and surface treatment with hydrofluoric acid (Comp-Etch). Most of the bond failures (86%) with the laboratory-cured microfilled composite were adhesive. With the light-cured composite, 69% of the failures were mixed adhesive-cohesive types.

Acid Etching, Dental↗
PubMed1993

The rationale for cemented total hip arthroplasty.

Long-term follow-up of early Charnley cemented THAs demonstrates excellent survival (Table 1). New techniques in cementing have improved the quality of the femoral cement fixation and have shown consistently good performance at 10-year follow-up. Noncemented designs have not yet demonstrated similar long-term results. Recent reports reveal osteolysis in noncemented prostheses, which is observed earlier than in cemented designs. This implies a greater role for polyethylene debris in the etiology of osteolysis. Polyethylene debris is produced not only at the articulation but also at the nonarticular metal-polyethylene interface in modular metal-backed acetabular components. This results in the production of additional plastic debris. Metal backing has not demonstrated any clinical improvement in the long-term performance of cemented acetabular components. Furthermore, it may be detrimental due to decreased polyethylene thickness, increased stress within the polyethylene, and an increased rate of polyethylene wear of both the articular and nonarticular surfaces. Multiple reports have demonstrated that titanium alloy is not an acceptable articulating surface because it has a poor resistance to abrasion. It can result in severe metallosis in the periarticular tissues, leading to progressive osteolysis and early failure of the arthroplasty. Caution is suggested in the widespread application of polymodular femoral components because the production of metallic debris may prove excessive. Cemented THA remains the gold standard by which other methods of fixation must be assessed. The enviable long-term results with early cementing techniques and the Charnley prosthesis will be difficult to match, even with developing technology.

Acetabulum↗
PubMed1996

[Bone cements and their uses in orthopedics and rheumatology. GRIBOI. Groupe de Recherche interdisciplinaire sur les Biomatériaux ostéo-articulaires injectables].

Acrylic cement has been used for total hip arthroplasty fixation for several years. Use of new cements for bony injections or for treatment of fractures is often misunderstood, in spite (or because?) of numerous paper in non-medical magazines. Acrylic cement continues to be the reference for bony cements. Most hip arthroplasties are still cemented, with good results in most cases, even after ten years. Other applications of acrylic cement are reported here, especially for percutaneous injection in metastatic vertebral lesions. New kind of cements are now available, especially pastes of carbonated apatite, and beta tricalcium phosphate-monocalcium phosphate monohydrate water mixtures. With this new family of injectable biomaterials we can hope the development of mini-invasive therapies for bone lesions, and first results appear to be very attractive. However continuous improvements of these materials and rigorous clinical evaluations are need.

Bone Cements↗