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PubMed1989

[Experimental study on the influence of various dental luting cements on the crown elevation during cementation].

Cementing manipulation is an important final step in adapting crown prosthesis to various oral environments. Preventing elevation of full cast crowns during cementation and improving adaptability of the margin after cementation are especially critical. The purpose of this article is twofold: 1) To clarify the relationship between the viscosity of dental cement and the extent of crown elevation, with special attention to viscosity changes occurring in various cement materials during the hardening process. 2) To study the effects on cemented-crown elevation of the space created between the abutment tooth and the crown, which may be partly related to dental cement behavior during cementation. A total of 4 cement materials was used: Elite Cement 100 as a zinc-phosphate cement, Super Bond C & B and Chemiace as MMA-resin cements containing 4-META, and Panavia EX as a phosphoricester cement. Viscosity was measured by means of MR-3 Soliquidmeter with a cone and plate system (Reheology Engineering). A brass material was processed to experimental crowns cemented to abutment teeth of brass. Crown elevation was measured by comparator (Measurescope Model II, Nikon). In addition, effects of the resistance of dental cement during cementation on crown elevation were studied for the sake of a comprehensive understanding of the elevation phenomenon. 1. Changes in dental-cement viscosity during the hardening process 1) Elite Cement 100 demonstrated the highest initial steady flow coefficient of viscosity. It was followed by Super Bond C & B, Chemiace, and Panavia EX, in that order. The t-test revealed significant differences among these cement materials (significance taken to be 1%). 2) As experimental temperature increased, the viscosity of all tested cement materials increased with progressive hardening. 3) With the passing of time, changes in torque, which represents a change pattern in viscosity, indicated that the tested cement materials have different viscosity-change patterns during the initial setting period. 4) From a clinical viewpoint, Super Bond C & B and Elite Cement 100 had very limited working time, whereas Chemiace and Panavia EX had relatively long working time. 2. Elevation after cementation of experimental crowns 1) For Elite Cement 100, mean elevation was 334microns, for Super Bond C & B 281 microns, for Chemiace 164microns, and for Panavia EX 130microns. The t-test revealed significant differences among these cement materials (significance taken to be 1%). 2) In all the cement materials tested, with a reliability of 99%, sequential correlation was observed between crown elevation and steady flow coefficient of viscosity.(ABSTRACT TRUNCATED AT 400 WORDS)

Cementation↗
PubMed1996

Retention of metal ceramic crowns cemented with resin cements: effects of preparation taper and height.

This study investigated the effect of varying crown preparation taper and height on the retention of metal ceramic crowns cemented with resin cements. In part 1, 32 extracted molars were divided into four groups. All groups received complete-veneer crown preparations, two with a 12-degree wall angle and two with a 35-degree wall angle. Crowns were cemented with zinc phosphate and dentin-bonded resin cements. After 24 hour water storage at 37 degrees C, the crowns were separated in tension. Crowns cemented with zinc phosphate were cleaned and recemented with another dentin-bonded resin cement and after similar storage, the crowns were separated. Mean separation forces of resin-cemented crowns were higher than those of crowns cemented with zinc phosphate cement. Mean separation force of 35-degree crowns cemented with one dentin-bonded resin cement was found to be significantly higher than for the 12-degree crowns cemented with zinc phosphate cement. In part II, 32 extracted molars were divided into two groups of complete-veneer crown preparations (group I preparations were 3 mm high and group II were 5 mm high). Crowns for all teeth were cast and cemented with zinc phosphate. After 48 hours' water storage at 37 degrees C, the crowns were separated in tension. Crowns and teeth were then cleaned and each group was subdivided into 2 equal subgroups. In one subgroup of teeth with 3 mm and in one with 5 mm high preparations, the crowns were recemented with one of the two resin cement systems and the other two subgroups were recemented with the other resin cement. After 48-hour water storage, the crowns were separated. Mean separation forces of the resin-cemented crowns were greater than those of crowns cemented with zinc phosphate. Also, mean separation force of 3 mm crowns cemented with one resin cement was significantly greater than the 5 mm crowns cemented with zinc phosphate. Cohesive dentin fracture on separation was observed with some resin-cemented crowns but never with crowns cemented with zinc phosphate.

Analysis of Variance↗
PubMed1999

Retention of adhesive cement on the tooth surface after crown cementation.

STATEMENT OF PROBLEM: Adhesive cements increase crown retention, but it is unknown if traces of cement remain undetected on the tooth surface after clinical removal of excess cement, which could exacerbate plaque retention. PURPOSE: This study measured the surface area, volume, mean depth, and maximum depth of a resin composite and a compomer luting cement left adherent on the tooth surface after removal of excess cement, as judged clinically. METHODS AND MATERIAL: Four groups of specimens (n = 48) were prepared for full coverage crowns: group AC bonding alloy with chamfer finish line, group G gold alloy with chamfer finish line, group PC porcelain with a chamfer finish line, and group PS porcelain with a shoulder finish line. Two profiles of the mesial and distal surfaces of the teeth were carried out: (1) tooth with crown seated but not cemented and (2) tooth with the crown cemented in place. Two cements and 2 methods of cement removal were studied. RESULTS: A 4-way analysis of variance for cement, crown type, method of removal, and tooth surface morphology showed that significantly greater volumes and mean depth, but not surface areas, of resin composite cement remained adherent than compomer cement (P<.05). Among crown types, significant differences were found for cement volume (group G>AC, G>PC, G>PS), cement surface area (group AC>PC, G>PC, G>PS), and maximum cement depth (group G>AC). There was no significant difference between the 2 methods of cement removal. Significantly larger surface areas and maximum depths of cement were retained on the anatomically grooved mesial surface of the maxillary first premolars than on the ungrooved distal surface. CONCLUSION: Subclinical cement retention occurred after crown cementation, which was influenced by cement, crown type, and tooth surface morphology but not method of cement removal.

Adhesives↗
PubMed1999

Comparison of fixation of the femoral component without cement and fixation with use of a bone-vacuum cementing technique for the prevention of fat embolism during total hip arthroplasty. A prospective, randomized clinical trial.

BACKGROUND: Acute hypotension, hypoxemia, cardiac arrest, and sudden death are well recognized complications during total hip arthroplasty, and they have been attributed to embolization of fat and bone marrow. An increase in intramedullary pressure in the femur is the most important pathogenic factor for the development of embolic events. Intravasation of fat, bone marrow, and bone debris during the implantation of a femoral component, and the embolization of these elements through the venous system located along the linea aspera and through the metaphyseal vessels, have been demonstrated experimentally and clinically. The purpose of the present study was to compare the effects of fixation of the femoral component without cement with those of fixation with a bone-vacuum cementing technique on the severity of embolic phenomena and cardiopulmonary impairment during total hip arthroplasty. Fixation with a conventional cementing technique was also evaluated as a control. METHODS: Sixty patients (sixty hips) were entered into a prospective, randomized clinical trial. The patients were assigned to one of three groups. Group 1 consisted of twenty patients who had the femoral component inserted without cement, Group 2 comprised twenty patients who had the component inserted with a conventional cementing technique, and Group 3 included twenty patients who had fixation with the so-called bone-vacuum cementing technique. In the hips in Group 3, a suction of -800 millibars (-80,000 pascals) was applied to a proximal drainage cannula placed along the linea aspera and a distal drainage cannula placed in the diaphysis in order to produce a vacuum in the medullary cavity of the femur during the application of cement and the insertion of the stem. Transesophageal echocardiography and hemodynamic and blood-gas analysis were performed during the operation. RESULTS: Severe embolic events (defined as a cascade of fine echogenic particles of less than five millimeters in diameter) were observed in seventeen (85 percent) of the twenty patients during insertion of the stem with use of a conventional cementing technique but in none of the patients who had the stem inserted without cement (p < 0.05). Insertion of the femoral component with the bone-vacuum cementing technique prevented embolic phenomena in all but one patient (5 percent). Arterial oxygen saturation decreased significantly (p < 0.05) from a mean of 99.5 to 92.9 percent after insertion of the stem with a conventional cementing technique, but only slight changes were observed in the patients who had fixation of the component without cement and in those who were managed with the bone-vacuum cementing technique. Intraoperative pulmonary shunt values increased a mean of 24 percent (p < 0.05) when the femoral component was inserted with a conventional cementing technique, but with the numbers available we did not detect a significant change in those values when the component was fixed without cement or when it was inserted with use of the bone-vacuum cementing technique. CONCLUSIONS: The present study showed that severe embolic events and intraoperative pulmonary impairment are common when a femoral component is fixed with use of a conventional cementing technique. The results clearly demonstrated a low risk of embolism during total hip arthroplasty when the femoral component was fixed without cement and when it was fixed with the bone-vacuum cementing technique. The ability of a patient to withstand an embolic event should be considered before fixation of the femoral component with use of a conventional cementing technique is planned.

Aged↗
PubMed2001

Cement-cement interface strength: influence of time to apposition.

Cement-cement interfaces were created under simulated operating-room conditions. In order to analyze the effect of time to apposition on interface strength, two cement surfaces were brought together 1, 2, 4, and 6 min after 1 min of mixing and 45 s of waiting. Cement-cement interface strength was evaluated with the use of a three-point bending to failure test. Scanning electron microscopy (SEM) images of the failed interface were obtained. The mean interface strength decreased when the cement-cement interface was time delayed. Compared to bulk cement, interface strength in time-delayed groups decreased 8% after 1-min delay (p=.037), 18% after 2-min delay (p=.0004), 20% after 4-min delay (p=.0005), and 42% after 6-min delay (p<.0001). No statistically significant differences in interface strength were found between the 2- and 4-min delayed groups (p=.73). SEM images revealed that after 6-min delay, up to 50% of the cement surface can remain unbonded, explaining the decrease in strength of the cement-cement interface as a function of time to apposition. This laboratory study indicates that time to apposition plays a critical role in cement-cement interface strength. If any cementing technique involves the joining of two cement surfaces, it is recommended that the two cement surfaces be mated together within 5 min and 45 s after the start of mixing (1 min mixing; 45 s waiting; 4 min delay), in order to obtain a strong cement-cement interface bond. Delay beyond this can result in substantial reduction in the strength of the cement-cement interface bond.

Adhesiveness↗
PubMed1998

Retention of three endodontic posts cemented with five dental cements.

STATEMENT OF PROBLEM: The retention of a post is believed to be a major factor in restoration survival. Therefore the cement with the greatest in vitro retention property should give the best performance for a restoration. PURPOSE: This study compared retentive values of three posts (Flexi-Post, AccessPost, and ParaPost) cemented with five cements (Flexi-Flow, zinc phosphate, Advance, Duet, and Ketac-Cem) plus a control group that consisted of a Flexi-Post No. 2 dowel without cement. MATERIAL AND METHODS: A total of 160 recently extracted human single-rooted teeth with crowns removed at the cementoenamel junction were divided into 16 groups of 10 samples. Post holes were prepared according to manufacturers' instructions. Posts were then cemented with one of the five cements. Each sample was placed into a specialized jig and on a tensile testing machine with crosshead speed of 0.638 cm/minute, applied until failure. A two-way analysis of variance and Newman-Keuls multiple range comparison tests were performed for all cemented groups. A one-way analysis of variance and a Student-Newman-Keuls multiple range comparison test were performed only for the groups with the Flexi-Post dowel, this included the no cement condition, with significant results if p < 0.05. RESULTS: Flexi-Post dowel with Flexi-Flow Natural cement obtained the highest retentive value (303.91 pounds). ParaPost dowel with Duet cement exhibited the lowest retention value (21.23 pounds). The Flexi-Post dowel demonstrated higher mean retention than AccessPost or ParaPost dowels, AccessPost dowel was higher than ParaPost dowel. Flexi-Flow cement had the highest overall mean retention followed, in decreasing order, by zinc phosphate, Advance, Ketac-Cem, and Duet cements. CONCLUSIONS: Flexi-Post dowel was the most retentive post studied with values ranging from 303.91 pounds with Flexi-Flow Natural cements to 150.93 pounds without cement. Flexi-Flow cements had a higher overall mean retention than other cements studied.

Analysis of Variance↗
PubMed1998

Surface roughness of debonded straight-tapered stems in cemented THA reduces subsidence but not cement damage.

Although stress analyses have shown that the mechanical endurance of cemented femoral THA reconstructions is served by stems that firmly bond to their cement mantles, retrieval studies suggest that this may be difficult to achieve. Clinical studies with roentgen stereophotogrammetric analyses have shown that stems may gradually debond from their cement mantle. Accepting the fact that stem debonding is unavoidable, stem subsidence and cement stresses can be reduced by increasing stem-cement friction, as indicated by finite element stress analyses. Hence, it can be hypothesized that debonded stems with high surface roughness values would damage the cement mantle to a lesser extent as compared to polished ones. To confirm this hypothesis, tapered stems with polished and rough surface finishes were implanted in cement mantles and cyclically loaded for 1.7 million times. It was investigated how surface roughness affected the damage in the cement mantle, and how it was related to prosthetic subsidence. The polished taper subsided considerably more than the rough one (630 vs. 270 microm at the end of the experiments). In addition, it was found that the polished taper displayed step-wise subsidence, which is probably due to the interaction of stick-slip processes at the interface, associated with creep of the acrylic cement. The rough taper subsided monotonously. Scanning Electron Microscopic (SEM) analysis of the taper-cement structures showed that the rough taper was completely debonded from the cement mantle, creating a gap at the interface, and that many large cement cracks and particles were created. Around the polished taper, only a few cracks were found and the taper-cement interface seemed undamaged. It was concluded that an increased surface roughness does not necessarily lead to a reduction in cement damage. On the contrary, compared to polished ones, debonded rough stems may produce more cement cracks and acrylic cement debris, and provide routes to transport these wear products. Hence, after failure of the stem-cement interface, straight-tapered stems with an increased surface roughness accelerate the failure process due to inferior fail-safe features. Consequently, in vivo subsidence patterns at the stem-cement interface should be considered in combination with the surface finish of the implant. An amount of post-operative subsidence of a rough stem may be much more damaging for the reconstruction than the same amount for a polished stem.

Bone Cements↗
PubMed1996

[An original procedure for cement diaphyseal extraction. The segmental cement extraction system or SEG-CES].

PURPOSE OF THE STUDY: We report our first eleven uses of a new cement mantle extraction system. The basis of this technique relies on a cement bone interface with a lower strength compared to the old cement-new cement interface. MATERIAL AND METHODS: The first stage of the procedure consists in a specific preparation of the inner surface of the old cement, mantle. It should be clean and dry after being abraded with a stainless steel wire brush. Then a thin cement syringe filled with low Viscosity PMMA cement, is injected in the old mantle in a retrograde fashion. A threaded rod with nuts is centered within the cement sheath to the bottom and held until the injected cement has fully polymerised. Then the threaded rod is unscrewed from the femur; nuts are established along the entire length of the cement column. To prevent trochanteric fracture occurring upon cement extraction, its is important to clear away sufficient bone from the lateral aspect of the canal. A series of extraction rods are then used to sequentially remove the cement mantle. The removal rod is screwed back into the threaded channel at a distance of every one to three nuts, and then attached to the slap hammer via a quick release connection. Cement extraction is performed using deliberate slaps of the slap hammer. The last segment is drilled with the use of a distal plug drill centering sleeve. After having inserted the plug removal rod, the last segment is extracted. We used this technique eleven times in 8 hips for 5 loosening of femoral component and 3 revisions hip arthroplasties without loosening and 2 revisions knee arthroplasties without loosening (an extraction system for the femur and the tibia). RESULTS: For the 5 loosening cases extraction was easy. In 2 cases, cement mantle was removed as a single "en bloc" piece. In the 3 other cases, the extraction was segmental only in the distal third of the cement mantle. Without loosening, the extraction was completely segmental. In all cases, cement mantles were successfully removed. There was no fracture and no loss of bone stock. There was only one "fissuration" alpha the great trochanter and we only made one distal window. All hip arthroplasties were replaced and arthrodesis were performed after removal of the knee arthroplasties. DISCUSSION: The cement-assisted mantle removal technique appears to be a simple, quick and effective methods for cement mantle removal. Perforation and diaphyseal window can be avoided by the technique even when loosening does not exist. However, it is necessary to establish a thorough preoperating plan in order to eliminate contraindications such as too narrow or too curved sheath. CONCLUSION: It appears that this new procedure will facilitate future reoperations which are reputed to be difficult and dangerous.

Bone Cements↗
PubMedDate not supplied

Retention of paraposts cemented with dentin-bonded resin cements.

The main purpose of this study was to assess the retention of Paraposts cemented with dentin-bonded resin cements in single-rooted teeth with elliptical canals. Forty-two mandibular premolars and canines were used in this study. The crowns of these teeth were removed 1 mm above the cementoenamel junction and the root canals instrumented to a depth of 8 mm to receive size 5 Paraposts. Prepared teeth were divided into six equal groups. Each group was assigned to a different cementation system at random. The six cementation systems used were: Fleck's Cement, Universal Post Cementation Kit, Prisma Universal Bond 3/Biomer, Scotchbond 2/Resiment, All-Bond 2/All-Bond C & B Cement, and Scotchbond Multi-Purpose/Resiment. Following post cementation, the teeth were stored in water at 37 degrees C for 24 hours, after which the posts were subjected to uniaxial tensile force on a testing machine until post separation occurred. Paraposts cemented with Prisma Universal Bone 3/Biomer or with Scotchbond Multi-Purpose/Resiment had significantly greater separation forces than posts cemented with any of the other cementation systems. Adhesive failure of the posts occurred in all of the specimens of the resin cement groups, whereas cohesive failure of the cement occurred in the majority of the specimens of the zinc phosphate cement group. The effects of thermocycling and post length (5 mm versus 8 mm) on the retention of Paraposts cemented with dentin-bonded resin cements were also investigated. Neither thermocycling nor post length had a significant effect on post separation force.

Analysis of Variance↗
PubMed2002

Comparison of microleakage of three acid-base luting cements versus one resin-bonded cement for Class V direct composite inlays.

STATEMENT OF PROBLEM: Demineralized dentin beneath set cement may adversely affect microleakage under fixed restorations. PURPOSE: Microleakage of direct composite inlays cemented with acid-base cements and a methyl methacrylate resin cement were evaluated to determine their effect on the integrity of the underlying hybridized dentin. MATERIALS AND METHODS: Sixty Class V box preparations (3 mm x 3 mm x 1.5 mm) were precisely prepared in previously frozen bovine teeth with one margin in enamel and another margin in dentin. Direct composite inlays (EPIC-TMPT) for each preparation were divided into 4 groups of 15 specimens each and cemented with 3 acid-base cements (control group): Elite, Ketac-Cem, Hy-Bond Carbo-Cem, and 1 adhesive resin cement: C&B Metabond. All specimens were stored in distilled water for 24 hours at 37 degrees C before immersion in 0.5% basic fuchsin for 24 hours. The dye penetration was measured on the sectioned specimens at the tooth-cement interface of enamel and cementum margins and recorded with graded criteria under light microscopy (Olympus Vanox-T) at original magnification x 50, 100, and 200. A Kruskal-Wallis and the Mann-Whitney test at P<.05 were used to analyze leakage score. RESULTS: All cementum margins of the 3 acid-base cements tested demonstrated significantly higher leakage scores than cementum margins for inlays cemented with the resin cement tested(P<.01). No leakage along the tooth-cement interface was found for inlays retained with the adhesive resin cement. CONCLUSIONS: Within the limitations of this study, the 3 acid-base cements tested exhibited greater microleakage at the cementum margins than did the adhesive resin cement that was tested.

Animals↗
PubMed2005

Bone-cement interface of the glenoid component: stress analysis for varying cement thickness.

BACKGROUND: Although shoulder arthroplasty is an accepted treatment for osteoarthritis, loosening of the glenoid component, which mainly occurs at the bone-cement interface, remains a major concern. Presently, the mechanical effect of the cement mantel thickness on the bone-cement interface is still unclear. METHODS: Finite element analysis of a prosthetic scapula was used to evaluate the effect of cement thickness on stresses and micromotions at the bone-cement interface. The glenoid component was all-polyethylene, keeled and flat back. Cement mantel thickness was gradually increased from 0.5 to 2.0 mm. Two glenohumeral contact forces were applied: concentric and eccentric. Two extreme cases were considered for the bone-cement interface: bonded and debonded. FINDINGS: Within cement, stress increased as cement thickness decreased, reaching the fatigue limit below 1.0 mm. Bone stress was below its ultimate strength and was minimum between 1.0 and 1.5mm. Interface stress was close to the interface strength, and also minimum between 1.0 and 1.5 mm. Both the decentring of the load and the debonding of the interface increased the stress. INTERPRETATION: A cement thinning weakens the cement, but also the bone-cement interface, along the back-keel edges. Conversely, a cement thickening rigidifies the cemented implant, consequently increasing interfacial stresses and micromotions. To avoid both excessive cement fatigue and interface failure, an ideal cement thickness has been identified between 1.0 and 1.5 mm.

Bone Cements↗
PubMed1997

Factors affecting cement strains near the tip of a cemented femoral component.

A generic three-dimensional finite-element model of the upper half of the femur containing a cemented femoral stem of a total hip arthroplasty was developed to study those factors influencing cement strains near the tip of a cemented femoral component. This generic model was verified through another three-dimensional finite-element model that had been created based on the precise geometry of a cadaver femur implanted with a contemporary cemented femoral component. This cadaveric femoral reconstruction had been created with strain gauges embedded in the cement mantle and was then loaded under conditions simulating single leg stance and stairclimbing. By use of the cement strains measured experimentally in the cadaver femur, and comparison of them with those obtained from the finite-element model of that cadaver femur, it was possible to establish proper material properties, boundary conditions, and loading conditions for the generic model. The generic model was then modified parametrically to determine those factors that influence the strains occurring within the cement mantle near the tip of a cemented femoral component. These models suggest that the single factor that most adversely influenced peak strains at or near the tip of the prosthesis was a thin cement mantle. This effect was present both when the cement mantle was reduced in thickness and when a similar effect occurred by virtue of a varus or valgus placement of the stem. Factors that decreased the peak cement strains near the tip of the femoral stem included a more flexible stem and thicker cement mantles. This effect of a more flexible stem could be obtained by changing the modulus of the metal implant by uniformly reducing the thickness of the stem, or by tapering the stem within the same bone geometry. Thicker cement mantles reduced both the axial and the shear strains occurring at the tip of the prosthesis. The presence or absence of a hole in the tip of the prosthesis per se, as for a centralizer, had no significant effect on the peak cement strains seen around the tip of the prosthesis; however, truncating the tip of the prosthesis from a hemisphere to a flat profile, which resulted in a sharp corner at the tip of the prosthesis, produced a 35% increase in cement strains at the tip as a result of a stress concentration effect. Thus, the common way of modifying the tip to have a hole for a centralizer, which involved truncating the tip, increased the cement strains occurring near the tip of the prosthesis.

Bone Cements↗
PubMed2005

Surface pretreatment for prolonged survival of cemented tibial prosthesis components: full- vs. surface-cementation technique.

BACKGROUND: One of few persisting problems of cemented total knee arthroplasty (TKA) is aseptic loosening of tibial component due to degradation of the interface between bone cement and metallic tibial shaft component, particularly for surface cemented tibial components. Surface cementation technique has important clinical meaning in case of revision and for avoidance of stress shielding. Degradation of the interface between bone cement and bone may be a secondary effect due to excessive crack formation in bone cement starting at the opposite metallic surface. METHODS: This study was done to prove crack formation in the bone cement near the metallic surface when this is not coated. We propose a newly developed coating process by PVD layering with SiOx to avoid that crack formation in the bone cement. A biomechanical model for vibration fatigue test was done to simulate the physiological and biomechanical conditions of the human knee joint and to prove excessive crack formation. RESULTS: It was found that coated tibial components showed a highly significant reduction of cement cracking near the interface metal/bone cement (p < 0.01) and a significant reduction of gap formation in the interface metal-to-bone cement (p < 0.05). CONCLUSION: Coating dramatically reduces hydrolytic- and stress-related crack formation at the prosthesis interface metal/bone cement. This leads to a more homogenous load transfer into the cement mantle which should reduce the frequency of loosening in the interfaces metal/bone cement/bone. With surface coating of the tibial component it should become possible that surface cemented TKAs reveal similar loosening rates as TKAs both surface and stem cemented. This would be an important clinical advantage since it is believed that surface cementing reduces metaphyseal bone loss in case of revision and stress shielding for better bone health.

Adhesiveness↗
PubMed2003

Tibial component fixation with cement: full- versus surface-cementation techniques.

Despite excellent outcomes with cemented tibial components in total knee arthroplasty, it still is debated whether the tibial stem should be cemented and what the optimal tibial stem design should be. Proponents of full cementation of the tibial stem and component state that better short-term and long-term component fixation is achieved when full cementation is used. Advocates for surface cementation contend that sufficient implant stability is achieved without the increased bone loss that occurs at revision and the stress shielding thought to be linked with cemented stems. This biomechanical cadaver study compared initial fixation and cement penetration depth in fully cemented versus surface cemented tibial trays with two different stem geometries (cruciate and I-beam) and compared two stem designs (cruciate and I-beam) fixed with surface cementation. Under an eccentric load, simulating three times body weight for 6000 cycles, there seems to be no difference in the micromotion of either tibial component implanted with surface or full cementation. Additionally, no difference in the average depth of cement penetration was detected between fixation techniques or stem types. The initial fixation stability of the surface cement technique seems correlated to the depth of cement penetration into proximal tibial surface. The current data support other studies which indicate that stability of surface-cemented tibial components may be related to the depth of cement penetration.

Adult↗
PubMed1987

A study of intrusion characteristics of low viscosity cement Simplex-P and Palacos cements in a bovine cancellous bone model.

Aseptic loosening is the most common long-term complication of cemented total hip arthroplasties (THA). The functional longevity of these implants depends on the bone-cement interface. The influence of cement injection pressure, type of cement, ambient temperature, chilling of the monomer, and centrifugation of cement-on-cement intrusion depth was investigated in specimens of bovine cancellous bone. In order to validate the bovine model for comparative purposes relative to use in man, a linear relationship between human and bovine cancellous bone was first demonstrated for various porosities and cement intrusion depth. Three cements (Low Viscosity Cement [LVC], Simplex-P, and Palacos) were intruded at three different pressures (20, 40, and 60 PSI) at the same ambient temperature and relative humidity into commercially prepared plugs of bovine cancellous bone. Cement intrusion depth was proportional to injection pressure for all three cements, but was significantly different for each cement at a given pressure. At 20, 40, and 60 PSI, Palacos had a cement intrusion depth of 1.4, 2.4, and 2.8 mm respectively, while the figures for Simplex-P were 2.2, 4.2, and 5.0 mm, and for LVC were 8.0, 12.0, and 14.6 mm. Ambient temperature had an inverse relationship with cement intrusion depth for all three cements given the same experimental conditions. Chilling the monomer increased the intrusion of Simplex-P to 5.8, 8.2, and 12.7 mm at 20, 40, and 60 PSI injection pressure respectively. Simplex-P intrusion depth was not modified by cement centrifugation at any of the three injection pressures tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗