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PubMed1995

Intravenous methylmethacrylate following cemented total hip arthroplasty.

Both cemented and noncemented techniques have been used for total hip arthroplasty (THA). Each technique has advantages and disadvantages. Among the disadvantages of cemented THA are several perioperative complications, such as intraoperative cardiac or respiratory failure and hypotension, called "cement implantation syndrome," and extrusion of cement beyond the confines of the medullary canal. Cement extrusion can be the result of overreaming of the femoral canal and cortical perforation. This is a worrisome finding, as the risk of subsequent femoral fracture at the site of perforation is increased. Extruded cement, however, does not always indicate a problem. Extruded cement located within the femoral venous system, intravenous methylmethacrylate, for example, is not associated with long-term complications. While uncommon, it is important to differentiate this finding from the more serious cortical perforation. We report four examples of intravenous methylmethacrylate following THA and describe the imaging features that allow differentiation of this entity from the more significant finding of cortical perforation.

Aged↗
PubMed2004

[Bilateral localized osteolysis after cemented total hip replacement].

The incidence of focal progressive osteolysis after THR is about 8% and 56%. Most often osteolysis is correlated with macrophage-induced osteoclastic bone resorption as a sequel of inflammatory reaction to wear particles. Recently these findings were published in respect to allergic reactions to implants, their alloying constituents, or bone cement. We report about a patient who developed bilateral localized osteolysis just below the cement mantle 5 years after cemented THR with a Müller straight stem. In the middle of the osteolysis small fragments of bone cement could be detected. Epicutaneous testing showed no reaction against cobalt, chromium, or nickel. Further epicutaneous testing in respect to ingredients of the bone cement were refused by the patient. Histological examination revealed a histiocytic reaction to wear particles and surrounding giant cells. To our knowledge, this is the first case of bilateral localized osteolysis after cemented total hip replacement. Taking all results of the current case into account, it is still unclear if a lymphocytic allergic contact reaction did contribute to the sequel of this case. Reports of immunologically induced incompatibility to components of bone cement, the development of extended testing procedures, and further scientific research should contribute to optimizing the care of patients.

Bone Cements↗
PubMed1982

Bond strength of orthodontic direct-bonding cement-bracket systems as studied in vitro.

Tensile bond strength and failure location were evaluated in vitro for three types of direct bonding cements (unfilled, low filled, and highly filled) with three types of brackets (polycarbonate, stainless steel, and ceramic) using natural teeth and plastic as substrates. An unfilled acrylic cement gave the highest values of bond strength for both the plastic and ceramic brackets, whereas a highly-filled diacrylate cement gave the highest bond strength for the metal brackets. Bond failures occurred at the bracket-cement interface with the stainless steel brackets with each cement, whereas failure locations occurred at the bracket-cement interface, within the cement, and within the bracket for the plastic and ceramic brackets. There were no significant differences in bond strength nor failure location between tooth and plastic substrates.

Dental Bonding↗
PubMed1985

Factors affecting in vitro bond strength of no-mix orthodontic cements.

The effects of cement thickness and time of exposure of primer to a stimulated oral environment on tensile bond strength were determined in vitro for three no-mix cements and a two-paste cement. Five shims produced increasing cement thicknesses, and a humidor at 37 degrees C simulated an oral environment. SY had the greatest tensile bond strength (0.92 kg/mm2), whereas UN and ML had similar strengths (0.60 kg/mm2 and 0.66 kg/mm2, respectively), when no shims were used. Generally, there was a decrease in tensile bond strength as thickness increased for all no-mix cements. The failure site was essentially at the cement-base interface. Failures within the cement were characterized by incomplete polymerization of the resin. There was a decrease in tensile bond strength which ranged from 11% to 24% after primed teeth were stored in a simulated oral environment for 1.0 minute for ML and 2.5 minutes for UN and SY. This decrease in strength was accompanied by an increase in percentage failure at the paste-primer interface.

Acrylic Resins↗
PubMed1978

Marginal microleakage in cemented complete crowns.

An in vivo study was developed to observe the penetration of 131INa around the margins of complete crown castings cemented with zinc phosphate cement with and without the application of different protective agents, with the following results. 1. Complete crowns cemented with zinc phosphate cement showed 131INa marginal leakage differences depending on the protective material used prior to cementation. 2. The best protective agent against marginal leakage according to this study was two layers of cavity varnish applied to the margins. 3. The amount of marginal leakage can be influenced by crown adaptation and the film thickness of the cement. 4. There were no differences between test periods of 1 hour or 21 days after cementation.

Anti-Infective Agents↗
PubMed1981

Influence of some factors on the fit of cemented crowns.

In the study, cast gold crowns were cemented similar to methods used for patients. Conclusions were that: 1. Fresh cement painted with a camel brush in the part of the crown to be cemented promotes a better fit than when the crown is completely filled with cement. 2. Mechanical vibration of the crown at cementation promotes a better fit. 3. Venting the crown, an internal relief by acid etching, or a combination of both these procedures improve the seating of the crown during cementation. 4. The association of one or numerous variables used in this study considerably improves the fit of the cemented crown.

Acid Etching, Dental↗
PubMed1993

Polymeric calcium phosphate cements: setting reaction modifiers.

In this study, the effects of several additives on the setting behavior and mechanical properties of polymeric calcium phosphate cements were investigated. The cements were derived from a polycarboxylic acid (PCA) and a calcium phosphate cement (CPC) powder that consisted of equimolar amounts of tetracalcium phosphate (TTCP) and dicalcium phosphate (DCPA). Retardation of the setting reaction in the PCA-CPC cements was observed by adding tribasic sodium phosphate and fluorides such as stannous fluoride, zirconium(IV) fluoride and titanium(IV) fluoride. It was found that increasing the concentration of these additives decreased the mechanical strength of the cements. However, improvements in both setting and mechanical properties for the PCA-CPC cements were observed by the combined use of 8% (w/w) stannous fluoride and 10% (w/w) tartaric acid. The mechanical properties of the PCA-CPC cement also were improved by adding calcium acetate, calcium methacrylate, zirconium(IV) sulfate and phosphonoacetic acid.

Acetates↗
PubMed2004

Modelling the fibrous tissue layer in cemented hip replacements: experimental and finite element methods.

The long-term fixation of cemented femoral components may be jeopardised by the presence of a fibrous tissue layer at the bone-cement interface. This study used both experimental and finite element (FE) methods to investigate the load transfer characteristics of two types of cemented hip replacements (Lubinus SPII and Müller-Curved) with a fibrous tissue layer. The experimental part investigated six stems of each type, where these were implanted in composite femurs with a specially selected silicone elastomer modelling the soft interfacial layer. Two fibrous tissue conditions were examined: a layer covering the full cement mantle, representing a revision condition; and a layer covering the proximal portion of the cement mantle, representing a non-revised implant with partial debonding and fibrous tissue formation. The FE method was used to model the full fibrous tissue layer condition, for both implants. The layer was modelled as a homogeneous, linearly isotropic material. A cross-comparison was performed of the experimental and FE findings. Agreement between experimental and FE models was verified to be within 15%. Varying the stiffness parameter of the FE soft tissue layer had little influence on the cortical bone strains, though had considerable effect on the cement strains. Stress shielding occurred for both stems under both fibrous tissue conditions, with the greatest reduction around the calcar. However, the cortical bone strains were generally larger than those for the equivalent well-fixed stems. The fibrous tissue layer was not found to increase the general strain pattern of the cement mantle, though localised regions of high stress were detected.

Arthroplasty, Replacement, Hip↗
PubMed2003

Interfacial fracture toughness between bovine cortical bone and cements.

To evaluate the bonding strength of the interfaces within the cemented arthroplasty system, various mechanical tests have been used. Conventional push-out and pull-out tests cannot reveal the actual bonding property of the interface because of the significant influence of surface roughness on the measured adhesion and the failure to account for the mismatch of elastic modulus across the interface. An alternative fracture mechanics approach, which considers the mix of opening and shear modes of the crack tip loading associated with the testing system and the elastic mismatch of materials across the interface, was used to evaluate the bonding ability of various cements. The four-point bend interfacial delamination test by Charalambides et al. (J. Appl. Mech. 56 (1989) 77; Mech. Mater. 8 (1990) 269) was used to quantify the bonding ability of cements. This method is arguably more suitable since the applied loading mode is comparable to the nature of loading within the prosthetic system, which is primarily bending. The bovine bone specimens were polished to mirror finish to eliminate bonding by mechanical interlocking. The results revealed minimal bonding for the conventional bone cement (PMMA) whereas substantial bonding was evident for the glass-ionomer cements tested. However, only the conventional glass-ionomer cements showed evidence of bonding on testing, while the resin-modified glass-ionomer cement (poly-HEMA) did not. The latter appeared to debond before testing because of excessive expansion stresses associated with swelling in water.

Adhesiveness↗
PubMed2003

Shrinkage stresses in bone cement.

Shrinkage of bone cement is reported primarily as a consequence of polymerisation, however thermal shrinkage also occurs as a result of its exothermic reaction. It is proposed that the latter effect is important, since it occurs late in the curing cycle at a time when the cement has attained its mechanical properties as a solid, and that residual stresses result. Observations from experiments and literature reports suggest that residual stresses may be sufficient to initiate cracks at the interface between hip replacement stems and cement.A theoretical model has been developed to calculate interference stresses, using thick-walled cylinder theory, on the basis of thermal and total shrinkages. Thermal shrinkage values were calculated using the coefficient of linear thermal expansion of bone cement, while total shrinkages were measured. Moduli of elasticity values were measured for acrylic bone cements ranging from 2.1 to 2.7GPa, as were Poisson's ratio values ranging from 0.38 to 0.46. Theoretical calculation of stresses in a cement mantle, based on assumptions of thermal shrinkage alone, predicted circumferential stresses of 8.4-25.2MPa for cement curing temperatures in the range 60-140 degrees C. It is concluded that cracks observed around hip prosthesis stems in laboratory specimens of bone cement are due to shrinkage and that residual stresses are sufficient to cause crack initiation prior to functional loading.

Bone Cements↗
PubMed2001

Effect of mixing methods on the compressive strength of glass ionomer cements.

OBJECTIVE: The purpose of the study was to evaluate the effect of the mixing method on the compressive strength and porosity of dental glass ionomer cements. METHOD: Five glass ionomer cements were chosen for use in the study. Two were hand mixed and three were encapsulated. The latter were mixed either by shaking or rotating. Following mixing by rotation some samples were centrifuged before use. The 24h compressive strength was determined for each cement/mixing regime combination and fracture surfaces were examined using SEM. RESULTS: The mixing method had a significant effect on compressive strength (P<0.05). For the luting/lining cement, hand mixing produced a significantly greater compressive strength (P<0.05). For the restorative cement, there were only small differences between specimens mixed by different methods and hand mixing gave a significantly lower compressive strength than mixing by rotation followed by centrifuging (P<0.05). Porosity was incorporated in all samples and low values of compressive strength were associated with larger pores. SIGNIFICANCE: The strength of glass ionomer cements is affected by incorporated porosity and this is dependent on the method of mixing. For some cements hand mixing is favoured in order to reduce porosity and increase strength but this is not generally applicable to all cements.

Capsules↗
PubMed1996

Impacted particulate allograft for femoral revision total hip arthroplasty. In vitro mechanical stability and effects of cement pressurization.

The initial migration and micromotion of the revision femoral stem stabilized with morselized impacted cancellous allograft and bone-cement and the influence of cement pressurization on fixation of the cement/allograft composite to the host were examined with human cadaver femurs. The stability of the allograft/cemented reconstruction was found to be intermediate between those of conventional cemented and cementless stems. In most cases, the stability of the reconstruction was closer to that of cemented than to that of cementless stems. This may account for histologic findings of graft incorporation in experimental and retrieved specimens reported by other authors. Although increased cement pressurization led to greater penetration of cement into the graft bed, greater cement penetration did not increase fixation strength of the cement/allograft composite to the host.

Adult↗
PubMed1992

A 12-month clinical evaluation of a glass polyalkenoate cement for the direct bonding of orthodontic brackets.

Glass polyalkenoate (ionomer) cements have the unique properties to physicochemically bond to enamel and base metals, and to leach fluoride over prolonged periods. These cements are hybrids of silicate and polycarboxylate cements and, like the silicate cements, retain a cariostatic action on adjacent enamel. This article reports on a 12-month clinical trial of a glass ionomer cement for the direct bonding of orthodontic brackets compared with a standard composite bonding adhesive. This study shows a significant difference in failure rates of direct-bonded orthodontic brackets cemented with a thick mix of Fuji I glass polyalkenoate cement (20%) compared with System I+ composite bonding resin (5%).

Acrylic Resins↗
PubMed1997

Fluoride release and shear bond strengths of three light-cured glass ionomer cements.

Little is known about the release of fluoride from light-cured glass ionomer cements when used as orthodontic bonding agents. Fluoride release from three "hybrid" light-cured glass ionomer cements was measured during a 42-day period after initial curing in an in vitro test that simulated their use as orthodontic bonding agents. On day 48, the bonded teeth were exposed for 30 seconds to a stannous fluoride gel and checked for fluoride release during the following week. One cement (BL) released the most fluoride after initial cure and after an exposure to a stannous fluoride gel on day 48. The other two hybrid cements exhibited both significantly less fluoride release than material (BL) and resembled for most of the 55-day duration the composite resin control. After the 55-day duration, shear bond strengths of the composite resin control were significantly higher than the three light-cured glass ionomer cements. The light-cured glass ionomer cements in this study released fluoride after initial curing and after exposure to a topical fluoride gel. This property may help reduce or possibly even prevent enamel decalcifications seen around bracket bases. At present, the shear bond strengths of the light-cured glass ionomer cements tested appear to be too low for routine orthodontic bonding agents.

Analysis of Variance↗
PubMed2003

The relationship between cement fatigue damage and implant surface finish in proximal femoral prostheses.

The majority of cemented femoral hip replacements fail as a consequence of loosening. One design feature that may affect loosening rates is implant surface finish. To determine whether or not surface finish effects fatigue damage accumulation in a bone cement mantle, we developed an experimental model of the implanted proximal femur that allows visualisation of damage growth in the cement layer. Five matte surface and five polished surface stems were tested. Pre-load damage and damage after two million cycles was measured. Levels of pre-load (shrinkage) damage were the same for both matte and polished stems; furthermore damage for matte vs. polished stems was not significantly different after two million cycles. This was due to the large variability in damage accumulation rates. Finite element analysis showed that the stress is higher for the polished (assumed debonded) stem, and therefore we must conclude that either the magnitude of the stress increase is not enough to appreciably increase the damage accumulation rate or, alternatively, the polished stem does not debond immediately from the cement. Significantly (P=0.05) more damage was initiated in the lateral cement compared to the medial cement for both kinds of surface finish. It was concluded that, despite the higher cement stresses with debonded stems, polished prostheses do not provoke the damage accumulation failure scenario.

Arthroplasty, Replacement, Hip↗
PubMed2000

Physical properties of resinous cements: an in vitro study.

The flow rate capacity, hydrolytic degradation and radiopacity of three resin-based cements were tested and compared with zinc phosphate cement, when used in accordance with the manufacturer's instructions. There are no significant differences among the cements with regard to the flow rate. The zinc phosphate cement showed superior hydrolytic degradation compared with the other cements tested. The cements presented different radiopacities and the zinc phosphate cement was the most radiopaque. The results suggest that the development of resin-based materials associated with adhesive procedures can increase the effectiveness of indirect restorations.

Analysis of Variance↗
PubMed2001

In vitro fatigue resistance of glass ionomer cements used in post-and-core applications.

STATEMENT OF PROBLEM: New glass ionomer cements exhibit better mechanical properties than their older counterparts. However, there is concern about their use as a core material in post-and-core applications. PURPOSE: This in vitro study evaluated the fatigue resistance of 2 new glass ionomer cements, Shofu Hi-Dense and Fuji IX GP, and compared their mechanical behavior as a core material under masticatory load with a silver-reinforced glass ionomer (ESPE Ketac-Silver) and a silver amalgam (Cavex Avaloy LC). MATERIAL AND METHODS: A total of 100 commercial plastic teeth were divided into 4 groups of 25 specimens each. Titanium posts were placed in the prepared root canals, and cores were built up in amalgam, silver-reinforced glass ionomer cement, and the 2 new glass ionomer cements. The post-and-core specimens were prepared for full cast metal crowns, which were fabricated and cemented with glass ionomer cement. Twenty specimens from each group were placed in a mastication simulator and cyclically loaded with a 400 N force for 1.5 million cycles. The 5 remaining specimens were used as controls. The specimens were sectioned and observed macroscopically and microscopically to determine the number of defects (alterations) in each material. Observed defects were verified with the Kruskal-Wallis test, and the 4 core materials were ranked with the Tukey multiple comparisons test. RESULTS: The mean rank sum values of the defects were as follows: Cavex Avaloy LC Amalgam (16.75), Fuji IX GP (38.50), Shofu Hi-Dense (39.53), and ESPE Ketac-Silver (67.22). The amalgam alloy was significantly different (P< .05) from the others. CONCLUSION: Under the conditions of this study, the 2 new glass ionomer cements used as core materials showed a higher number of defects than amalgam. These results suggest that their fatigue resistance may be inadequate for post-and-core applications.

Cermet Cements↗
PubMed2004

Durability of the cemented femoral stem in patients 60 to 80 years old.

The importance of surface roughness and durability of fixation of the cemented femoral stem were examined. Three cohorts of patients approximately 60 to 80 years old, had cemented total hip replacements: Charnley (1978-1983) with first-generation cement technique consisting of canal-plugging and digital packing; Omnifit (1986-1991), and Ranawat-Burstein (R-B) Interlok (1992-1994) with modified third-generation cement technique. Kaplan-Meier survivorships, using failure for all causes (best case) were 90% +/- 5.1% at 20 years for the Charnley 95.1%+/- 3.4% at 15 years for the Omnifit and 99.5% +/- 0.5% at 9 years for the R-B Interlok prosthesis. Log rank test with paired data showed no significant differences between the groups for mechanical failure as an end point. Comparisons of survivorship curves for failure from all causes showed significant differences between the Charnley compared with the Omnifit and Interlok series respectively, with no significant differences between the Omnifit and R-B Interlok series. The cemented femoral stem, with a good cement mantle and surface roughness ranging from 30 to 150 microinches, did not show any significant differences in mechanical failure. Other variables such as stem centralization and low polyethylene wear need additional evaluation in survivorship of cemented total hip replacements.

Adult↗