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PubMed2000

Failure of total hip arthroplasty with Boneloc bone cement.

Early failure of Boneloc cemented total hip arthroplasty is well documented. However, information regarding the long term prognosis is scanty. The aim of this study was therefore to assess the long term failure rate of total hip replacement with Boneloc bone cement. Between January 1991 and March 1992, Boneloc bone cement (Polymers Recontructive A/S, Farum, Denmark) was used in 42 consecutive total hip replacements in 42 patients. The average age of the patients was 75 years. There were 25 women and 17 men. The diagnosis at operation was osteoarthritis in all cases. A cemented Muller Taperloc femoral stem was used with a cemented Muller acetabular cup (Biomet, Warsaw, USA). The follow-up time was 9 years. All patients underwent radiographic control the first postoperative year and annually after 1995. To date 21 patients have been revised for aseptic loosening at a mean of 5 years (range: one year to 8 years). Three other patients have definite radiographic evidence of loosening. The overall failure rate is therefore 24/42 = 57%. Our results confirm the previously reported poor results of Boneloc bone cement for hip arthroplasty and support the recommendation of indefinite follow-up for surviving prostheses. New prosthesis designs and new cements should have documentation, including laboratory tests and randomized clinical studies with radiostereometric evaluation. However, the ethical responsibility rests heavily on the shoulders of the clinician to make a correct analysis of the need for a new product before he begins to use it.

Aged↗
PubMed2002

Lung function and surface electromyography of intercostal muscles in cement mill workers.

Impairment of pulmonary function in cement mill workers has been previously reported without considering a variety of parameters that can help evaluate more thoroughly the effect of cement dust on the respiratory system. In addition, an integrated approach has not been considered to assert the involvement of respiratory muscles. Therefore, in the present study spirometry and surface electromyography (SEMG) of intercostal muscles were used for indicating pulmonary impairment. In this study, a group of 50, apparently healthy volunteers, male cement mill workers aged 20-60 years with exposure of 13 years on average, were randomly selected. They were matched with another group of 50 control healthy male subjects in terms of age, height, weight and socioeconomic status. Both groups met the standard exclusion criteria. Spirometry was performed on an electronic spirometer, while SEMG of intercostal muscles was performed by using a chart recorder. The results demonstrated statistically significant reduction in lung function parameters i.e., force vital capacity (FVC) (p < 0.0005); force expiratory volume in first second (FEV1) (p < 0.0005); peak expiratory flow (PEF) (p < 0.005); and maximum voluntary ventilation (MVV) (p < 0.0005) in cement mill workers, when compared with controls. However, the FEV1/FVC ratio was significantly higher (p < 0.025) in cement mill workers. Similarly, the parameters obtained from SEMG of intercostal muscles, i.e. number of peaks (NOP) (p < 0.0005); maximum peak amplitude (MPA) (p < 0.0005); peak to peak amplitude (PPA) (p < 0.0005); duration of response (DOR) (p < 0.0005) and maximum peak duration (MPD) (p < 0.0005), were significantly lower in cement mill workers than in controls. It is concluded that exposure to cement dust not only impairs lung function but also affects costal muscle performance, thus possibly indicating the decreased lung and thoracic compliance.

Adult↗
PubMed2002

Hematological changes in cement mill workers.

OBJECTIVES: Considering the hazards of exposure to cement dust, this study incorporated basic hematological parameters, erythrocyte sedimentation rate and the total leukocyte count. The idea was to identify a simple, readily available and cost effective screening test that could help in identifying the presence of disease, its severity, or both in cement mill workers potentially related to their work place. METHODS: This study was carried out in the Department of Physiology, Faculty of Health and Medical Sciences, Hamdard University, Karachi and the University of Karachi, Pakistan, during the time frame 1999-2000. In this study a group of 50, apparently healthy volunteers male cement mill workers were randomly selected with ages ranging from 20-60 years. They were matched with another group of 50, control healthy male subjects in terms of age, height, weight and socioeconomic status. Both groups met with exclusion criteria as per standard. The total leukocyte count was performed on an auto analyzer, (Symex-K-1000 CP-Analyzer, Japan) and the erythrocyte sedimentation rate was measured by Westergren tube method. Results were compared in a mean, and on the basis of, period of exposure in a cement mill. RESULTS: In the present study, the mean values of erythrocyte sedimentation rate (p<0.05) and total leukocyte count (p<0.02) significantly increased, but the parameters do not revealing statistically significant differences between 2 groups on the basis of duration of exposure in a cement mill. CONCLUSION: This study has shown that exposure to cement dust causes increased mean values of total leukocyte count and erythrocyte sedimentation rate. However, this change is not related to the duration of exposure in a cement mill.

Adult↗
PubMed2004

Stabilization effects of surplus soft clay with cement and GBF slag.

Utilization of industrial waste and surplus construction soft clay as construction material was recommended, and many attempts at geotechnical waste utilization were undertaken. This study aimed at the application of cement and a kind of industrial wastes, i.e. granulated blast furnace slag, on stabilization of surplus soft clay. The results showed that the cement and slag can successfully stabilize Ariake clays even though this high organic clay fails to be stabilized by lime and cement. Addition of slag in cement for stabilization induces higher strength than cement alone for longer curing time. The application of the cement with slag is more suitable than cement alone for stabilization because of economical consideration.

Aluminum Silicates↗
PubMed2004

Reuse of fresh water sludge in cement making.

With the increasing demand for high quality water, a large quantity of chemical agent must be added in the water purification process, which in turn generates enormous amount of fresh water sludge. Of all the options for sludge disposal, sludge reuse has been considered most economical and environmentally sound. This study evaluated the possibility of incorporating fresh water sludge in the making of Portland cement through the sintering process. The goal was to search for the optimal condition to maximize the replacement of clay with the fresh water sludge. Characteristics of fresh water sludge were collected and analyzed. The analysis showed that water source and water treatment process dominate th characteristics, particularly the chemical composition of the fresh water sludge. The fresh water sludge was mixed with the cement clay in various percentages, from 0% to 100%, as raw material for cement-making. The effects of its addition on the sintering condition and the quality of cement were evaluated. The analysis of the clinkers showed that the addition of the fresh water sludge did not change the phase form and the f-CaO content of the cement. The compressive strength of the masonry increased with the increasing addition of fresh water sludge. All cement products made from various replacement ratios met the Chinese National Standard of first degree Portland cement.

Aluminum Silicates↗
PubMed2005

Interfacial strength of cement lines in human cortical bone.

In human cortical bone, cement lines (or reversal lines) separate osteons from the interstitial bone tissue, which consists of remnants of primary lamellar bone or fragments of remodeled osteons. There have been experimental evidences of the cement line involvement in the failure process of bone such as fatigue and damage. However, there are almost no experimental data on interfacial properties of cement lines in human cortical bone. The objective of this study is to design and assemble a precision and computer controlled osteon pushout microtesting system, and to experimentally determine the interfacial strength of cement lines in human cortical bone by performing osteon pushout tests. Thirty specimens were prepared from humeral diaphyses of four human subjects. Twenty specimens were tested under the condition of a small hole in the supporting plate, in which the cement line debonding occurred. The cement line interfacial strength ranged from 5.38 MPa to 10.85 MPa with an average of 7.31 +/- 1.73 MPa. On the other hand, ten specimens were tested under the condition of a large hole in the supporting plate, in which the shear failure inside osteons was observed. The specimens tested under the condition of the large hole resulted in an average shear strength of 73.71 +/- 15.06 MPa, ranging from 45.97 MPa to 93.74 MPa. Therefore, our results suggest that the cement line interface between osteon and interstitial bone tissue is weaker than that between bone tissue lamellae.

Biomechanical Phenomena↗
PubMed1975

Xenopus laevis cement gland as an experimental model for embryonic differentiation. I. In vitro stimulation of differentiation by ammonium chloride.

Ectoblastic cells explanted from the animal pole of young Xenopus laevis gastrulae have been cultured in vitro. When these cells were cultured for five days in standard salt solutions they formed atypical epidermis. When they were first submitted for 6 h to Holtfreter solution containing ammonium chloride and then transferred for five days in standard Barth's solution they underwent differentiation into typical cement gland tissue. The optimum concentration of ammonium chloride was 10 mM. Below and above this concentration the resulting cement glands had a smaller volume. The optimum duration for the initial stimulation with 10 mM ammonium chloride in Holtfreter solution was 6 h. Shorter stimulation times produced only small cement glands. Longer initial incubations in ammonium chloride resulted in progressive dissociation of the explants. To obtain the best differentiation into cement gland it appeared that the pH of the ammonium chloride solution should be between 7-5 and 7-7. When the stimulation is performed under these optimum conditions the cement gland measured after five days of culture accounts for 80-90 percent of the explanted tissue. This means that all or almost all of the competent superficial layer of the ectoblastic cells underwent differentiation into cement gland. No other differentiated tissue was observed in the explants. The cement gland is a very simple organ containing only one single cell type. The gland obtained under the described in vitro conditions is therefore proposed as an experimental model for biochemical studies on early embryonic differentiation.

Ammonium Chloride↗
PubMed1979

Experimental reaming of the proximal femur and acrylic cement implantation: vascular and histologic effects.

The technique of microangiography and correlated histology was used, in experiments on the proximal femora of mature mongrel dogs, to study the effects of simple medullary reaming and of reaming followed by insertion of acrylic cement. The hip joints were not disturbed. A segment of Steinmann pin, representing the stem of a hip prosthesis, was inserted into the cement as it was polymerizing. The most significant results, after reaming alone, were devascularization and apparent necrosis of large areas of the cortex of the subtrochanteric femoral diaphysis. Full recovery was observed in 6 months. However, when acrylic cement was introduced following the reaming, extensive necrosis of the inner layers of the diaphyseal cortex was still present after a year, when the observations were terminated. The presence of necrosis of bone was judged by the lack of visible osteocytes in the lacunae. After the devascularization caused by filling the diaphyseal medulla with acrylic cement, the apparently necrotic cortex was revitalized without osteoclasia. That is in contrast to the results in another study in which osteoclasia and osteoneogenesis were required to restore cortex with empty cell lacunae. This raises the question of dormant osteonecrosis in contrast to total osteonecrosis. These studies show, in thin histologic preparations, acrylic bone cement in situ in the tissues. A fibrous membrane was found at the cement-bone interface in most areas. It was thicker in the diaphysis than in the metaphysis. The physiologic effects of acrylic cement implantation are considered to be likely factors in the loosening which is observed clinically when the femoral components of hip prostheses are under protracted stress.

Acrylic Resins↗
PubMed1985

[Burns related to the use of cement. Apropos of 4 cases].

Four patients suffering from cement burns are reported. Lesions consist of sharp-edged necrotic ulcerations, leaving hypertrophic scars after a normal course of six weeks to two months. Patch-tests are constantly negative in all patients. Quick-setting cement, and in particular ready mixed cement, is usually responsible for such lesions. Additional factors include prolonged contact with cement, pressure and/or occlusion. Cement burns are therefore considered to be alkaline burns. An increased use of premixed cement by non-occupational users play an important role in the actual frequency of such lesions. Mandatory preventive measures are needed; correct use of cement, adequate protective garments, cleaning and drying of the skin after work, etc.

Adult↗
PubMed1984

Femoral cement pressurization during total hip arthroplasty. The role of different femoral stems with reference to stem size and shape.

Aseptic loosening is the most common cause of femoral component failure following total hip arthroplasty (THA). Improvements have been made in cementing technique, but little attention has been directed toward the effect of different femoral components on bone cement pressurization. The effect of three different femoral stem sizes in one femoral canal and of eight different femoral stem designs on bone cement extrusion pressures was investigated on autopsy specimens. In a given femur significant increases in bone cement pressurization were achieved about the distal two-thirds of the femoral component in progressing from a small to a medium to a large stem. Similarly, femoral stems with rounded, rectangular cross sections generated greater bone cement pressurization about the distal two-thirds of the stems than stems trapezoidal and diamond-shaped in cross section due to their increased stem volume. The results of this study favor the use of the largest femoral component stem, preferably one with a rounded, rectangular cross section, that will fit comfortably in a given femoral canal and still allow a surrounding cement envelope such that bone cement pressurization will be enhanced with implant introduction.

Cadaver↗
PubMed1988

Improved cementation in total hip replacement.

Insufficient cementation has been suggested to be the most common cause of loosening of the femoral component after total hip arthroplasty. A clinical and radiographic study of 129 consecutive, primary total hip replacements was performed 5 years after surgery, in order to evaluate the significance of femoral plugging, special attention being focused on cementation and radiographic loosening. A polyethylene medullary plug was used in 78 hips which were compared with 51 non-plugged hips with respect to the clinical course and radiographic appearance. The cement mantle around the femoral component was thicker, and the packing of cement significantly improved when the plug was used. The frequency of radiographic loosening was smaller in the plugged group but with no statistical significance. There was no difference in clinical results between the compared groups. Our results indicate that medullary plugging improves the cementation and in particular prevents insufficient cementation of the femoral component.

Adult↗
PubMed1980

Frozen-slab technique for mixing zinc phosphate cement for cast restorations.

The technique for handling zinc phosphate cement can be altered to achieve enhanced properties of the cement. The compressive strength of the material can be decreased. The film thickness can be maintained within acceptable limits, and the possibility of pulpal damage can be kept low by maintaining temperature changes in the cement similar to those obtained from a room temperature-slab technique. The technique advocated by this report is as follows: 1. Store the aluminum slab with vinyl covering in a freezer at -15 degrees C to -20 degrees C in a plastic bag to prevent ice formation on the surface. 2. Remove the slab when ready to mix. 3. Quickly wipe the slab clean. 4. Dispense twice as much powder and liquid as recommended on the slab. 5. Start timer. 6. Slowly incorporate the powder into the liquid over a large area of the slab for 2 minutes. 7. Allow the mix to remain on the slab. 8. The instrument for placing the cement can be placed under the slab. The casting can be placed on a corner of the slab. 9. At 10 minutes, place the cement into the casting(s) and seat. 10. Remove excess cement. 11. Clean the slab by rinsing in water and gently wiping. 12. Dry the slab, place it in the plastic bag, and return it to the freezer.

Aluminum↗
PubMed1990

Deformation of crowns during cementation.

Deformation of crowns during cementation was investigated by a simple loading system of defined crowns with silicone fluids as cements. Deformation of the crowns was measured by long stain gauges that encircled the cervical margins. Die spacing was simulated by etching the die. Venting was simulated by removing a small screw. Deformation of the crowns was decreased by decreasing the viscosity of fluid, increasing the thickness of the crowns, and venting. Etching the die decreased the seating times of the crowns, but did not alter the level of deformation. Terminal cementation with zinc phosphate cement confirmed the presence of crown deformation during cementation. The results have consequences for bonded and all-ceramic crowns, and explain several clinical phenomena. It is suggested that low viscosity cements, low seating forces, and die spacing be used to decrease the deformation of crowns during seating. The importance of passive fitting of the crown to the tooth is stressed.

Acid Etching, Dental↗
PubMed1991

An investigation of dental luting cement solubility as a function of the marginal gap.

The purpose of this study was to investigate the rate of type I zinc phosphate cement solubility as it relates to the degree of marginal opening. Standardized test samples were constructed that would simulate clinically relevant marginal gaps of 25, 50, 75, and 150 microns and their subsequent cement lines. The study was divided into two phases. Phase 1 evaluated the effects of simple diffusion on cement solubility in a static environment, whereas phase 2 investigated the effects of convective forces on cement dissolution in a dynamic environment. Both the phase 1 and phase 2 studies demonstrated no significant difference in the rate of cement dissolution for the 25-, 50-, and 75-micron test groups. The 150-micron test groups for both studies, however, demonstrated an increase in the rate of cement dissolution. The results of the phase 1 and phase 2 studies should not be compared because different methodologies were used.

Analysis of Variance↗
PubMed1994

The effect of dowel lubrication on retention of resin-cemented dowels.

Threaded dowels were cemented into prepared canals of extracted human teeth by use of unfilled Bis-GMA resin cement. One half the dowels were lubricated before cementation, unscrewed partially, and reseated to original length after cement had set, to assure retrievability. There was no significant difference in mean tensile force required to dislodge the dowels cemented with or without prior lubrication. Lubrication of dowels makes them predictably and easily retrievable with no short-term effect on tensile strength of the cemented lubricated dowels. Long-term effects of the lubricant on the resin are unknown.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1989

Interaction of dental cements with the complement system.

The relative complement-activating properties of several dental cements were investigated. After the cements were incubated with fresh human serum as a source of complement, the percent of the electrophoretic conversion was assessed by means of the C3 crossed-immunoelectrophoresis technique. It was determined that the ZnO-containing cements--which include zinc phosphate, zinc polycarboxylate, zinc oxide eugenol, and zinc hexyl vanillate--each caused C3 conversion, indicative of complement activation. Glass-ionomer cement, which does not contain ZnO, did not activate the complement system. In dose-response studies, ZnO at relatively low concentrations was effective in causing C3 conversion, while at higher concentrations ZnO appeared to block C3 conversion. Supernatants from ZnO suspensions also caused C3 conversion. Cement particle size, as well as soluble degradative products containing ZnO or Zn++, were suggested as possible factors contributing to the differential effects of the dental cements on complement activation and/or function.

Complement Activation↗
PubMed1993

A comparison of the shear bond strengths to a resin composite of two conventional and two resin-modified glass polyalkenoate (ionomer) cements.

The inability of resin composite to bond directly to dentine has compromised the clinical success of this restorative material. This problem may be overcome by the so-called laminate technique in which glass polyalkenoate cement is placed upon dentine and then covered with a resin composite. The cement both adheres to dentine and affords micromechanical attachment to the composite. The introduction of the resin-modified glass polyalkenoate cements (RMCs) offers the potential for chemical union between cement and composite. This investigation examined the shear bond strengths of P-50 resin composite to four glass polyalkenoate lining materials, with and without the application of an intermediate bonding agent (Scotchbond 2). Two of the cements were RMCs (Vitrebond, XR-Ionomer) and the others were conventional base materials (Baseline, Ketac-Bond). The bond between P-50 and Vitrebond with or without Scotchbond 2 was significantly (P < 0.01) stronger and more consistent (P < 0.05) than that observed for all other materials. The treatment of the conventional materials and XR-Ionomer with Scotchbond 2 significantly (P < 0.01) improved the bond strengths to P-50. It is concluded that Vitrebond formed the most favourable cement-resin composite bond and that the other materials studied should be used in conjunction with an effective intermediate bonding agent, such as Scotchbond 2.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2005

Antibacterial properties of 4 orthodontic cements.

BACKGROUND: White spot lesions are observed in nearly 50% of patients undergoing orthodontic treatment. Long-lasting antibacterial properties of orthodontic cements can reduce this phenomenon. METHODS: The antibacterial properties of 4 orthodontic cements were evaluated by direct contact test (DCT) and agar diffusion test (ADT). With the DCT technique, octet specimens of glass ionomer (CX-Plus; Shofu, Kyoto, Japan), reinforced glass ionomer (GC Fuji ORTHO LC; GC Corporation, Tokyo, Japan), and 2 composite (Transbond XT and Transbond Plus; 3M Unitek, Monrovia, Calif) orthodontic cements were placed on the sidewalls of wells of a 96-microtiter plate. Streptococcus mutans cells (ca. 1 x 10(6) ) were placed on the surface of each specimen for 1 hour at 37 degrees C. Then, fresh media was added to each well, and bacterial growth was monitored for 16 hours with a temperature-controlled spectrophotometer. This was repeated on specimens aged in phosphate-buffered saline for 1 day, 1 week, and 1 month. The ADT was performed by placing specimens in wells punched in agar plates. RESULTS: Measurement of the halo in bacterial lawn after 48 hours showed that only the glass ionomer cement (CX-Plus) produced an inhibition zone (1.2 mm around the sample). Results at the DCT showed that only the reinforced glass ionomer cement (GC Fuji ORTHO LC) exhibited potent antibacterial activity, which lasted 1 week and diminished over the next 3 weeks. CONCLUSIONS: The reinforced glass ionomer cement possessed the most potent and long-lasting antibacterial activity.

Acrylic Resins↗