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PubMed2002

Biomechanical evaluation of proximal humeral fracture fixation supplemented with calcium phosphate cement.

BACKGROUND: Proximal humeral fractures are common injuries, and numerous surgical methods have been described for their treatment. The biomechanical characteristics of various internal fixation devices that are used to treat these fractures have not been extensively studied, nor has the potential beneficial effect of calcium phosphate cement supplementation. METHODS: We used a cadaveric three-part proximal humeral osteotomy model to perform a biomechanical evaluation of three types of internal fixation devices: a cloverleaf plate, an angled blade-plate, and Kirschner wires. The effect of supplementing the fixation with SRS (Skeletal Repair System) calcium phosphate cement was evaluated as well. Eighteen pairs of fresh-frozen humeri were obtained, and the bone-mineral density of each specimen was measured. In each pair, one specimen was secured with internal fixation alone and the contralateral specimen was secured with internal fixation combined with calcium phosphate cement. The specimens were tested cyclically in abduction and in external rotation for 250 cycles to evaluate interfragmentary motion. The specimens were then loaded to failure in external rotation to measure torsional load to failure and torsional stiffness. RESULTS: Overall, there were no significant differences between the specimens treated with the blade and cloverleaf plates, whereas the specimens treated with Kirschner wires demonstrated more interfragmentary motion, less stiffness, and lower torque to failure. In general, supplementation with calcium phosphate cement led to significant improvements in the mechanical performance of all three forms of internal fixation as demonstrated by a significant decrease in interfragmentary motion, a significant increase in torque to failure, and a significant increase in torsional stiffness. The addition of calcium phosphate cement increased the stiffness of even the most osteoporotic specimens to levels that were higher than those of the most osteodense specimens that had been treated with internal fixation alone. CONCLUSION: The initial biomechanical properties of internal fixation as measured with use of a proximal humeral osteotomy model and three methods of fixation were significantly improved by the addition of calcium phosphate cement.

Aged↗
PubMed2004

Revision total hip arthroplasty with use of a cemented femoral component. Results at a mean of ten years.

BACKGROUND: Revision of the femoral component of a total hip replacement with use of cement has been associated with early mechanical failure due to aseptic loosening. The purpose of the present study was to determine the long-term survival after revision of the femoral component with cement and to identify factors that were predictive of failure. METHODS: The results of 129 revision total hip arthroplasties that had been performed with use of a cemented femoral stem were reviewed to determine component survival. Ninety-seven hips that had been followed for a minimum of five years were included in survival analysis and tests of significance. Harris hip scores were used to quantify clinical outcomes. Clinical and surgical factors were analyzed to determine whether they were predictive of failure. RESULTS: The mean Harris hip score improved from 52 points preoperatively to 71 points at the time of the most recent follow-up (p < 0.001). The ten-year survival rate was 91% with rerevision of the femoral component because of aseptic loosening as the end point and 71% with mechanical failure as the end point. Patients who were more than sixty years old had greater long-term component survival and less pain than younger patients did (p < 0.05). A good-quality postoperative cement mantle was associated with better long-term radiographic signs of fixation (p < 0.001). Poor femoral bone quality was associated with an increased rate of rerevision for aseptic loosening (p = 0.021). CONCLUSIONS: Revision with use of a cemented femoral component remains an option for selected patients, with an acceptable ten-year survival rate and fair radiographic evidence of fixation. Our patients had acceptable clinical outcomes at ten years, and few had notable pain. The best results may be achieved in older patients (those who are sixty years old or more) with adequate bone stock who are managed with modern cementing techniques.

Aged↗
PubMed1981

Rheology of acrylic bone cements.

The rheological properties of setting acrylic bone cements were examined with a rotational cone and plate viscometer. The cements were tested over two orders of magnitude of shear rate to determine the nature of any non-Newtonian flow behavior. All three cements behaved with moderate pseudoplasticity (i.e., shear thinning) during setting, suggesting the use of higher pressures during administration for better flow and penetration. The low viscosity brand was found to be nearly one-half as viscous as the conventional cements during the working time (i.e., 2-5 minutes). A series of sieving experiments were performed to determine the particle size distributions of the powder components. Statistical analysis (chi square) showed the cements to have different distributions, with the low viscosity brand containing a larger proportion of smaller polymer particles. This difference is thought to contribute to the lower viscosity of this cement.

Bone Cements↗
PubMed1994

Early failures among 14,009 cemented and 1,326 uncemented prostheses for primary coxarthrosis. The Norwegian Arthroplasty Register, 1987-1992.

In the Norwegian Arthroplasty Register, 15,335 primary total hip replacements (THR) in patients with primary arthrosis were followed for 0-5.4 years. The Kaplan-Meier estimate of cumulative failure (revision) after 4.5 years was 2.7 percent for cemented THR, compared to 6.5 percent for uncemented. In patients under 65 years the cumulative revisions for cemented and uncemented THR were 3.3 and 7.9 percent. For the acetabular components, the cumulative failures were 0.6 percent for cemented and 1.7 percent for uncemented, and for femoral components 1.7 and 3.9 percent after 4.5 years. Adjusting for age and sex using a Cox regression model, 2 times higher rates of failure were found comparing uncemented to cemented THR. The results for uncemented prostheses were more unfavorable in young patients. In men and women under 60, the revision rates were increased 6 and 3 times, respectively, for patients with uncemented THR compared to those with cemented THR. Restriction of the end-point to revision for aseptic loosening gave results similar to the over-all results. No difference between cemented and uncemented THR was seen for revisions due to infection, whereas the most unfavorable results for uncemented THR were seen when revisions due to causes other than infection and aseptic loosening were considered.

Adult↗
PubMedDate not supplied

Passivity of fit and marginal opening in screw- or cement-retained implant fixed partial denture designs.

The relationship of stress generation upon placement of cement-retained or screw-retained implant restorations has not been thoroughly investigated. Passivity of fit and marginal discrepancies of screw- and cement-retained implant fixed partial denture (FPD) designs were determined using a photoelastic model of a partially edentulous posterior mandibular arch with 3 screw-type implants. Buccal and lingual marginal openings, measured with a traveling microscope before cementation or screw tightening, revealed no statistical difference in adaptation between designs. Screw tightening caused a reduction in marginal opening (changes significant, P < .05). The opening with the cemented FPDs was similar before and after cementation. Photoelastic evaluation of the FPDs showed that cement-retained FPDs exhibited a more equitable stress distribution than did their screw-retained counterparts.

Cementation↗
PubMedDate not supplied

The effect of surface treatment on the shear bond strength of luting cement to a glass-infiltrated alumina ceramic.

PURPOSE: The aim of this study was to evaluate the effect of three different surface treatments on the bond strength of four different luting cements--three bis-GMA-based resin cements and a compomer cement--to In-Ceram. MATERIALS AND METHODS: Eight In-Ceram samples were used for each experimental group. The samples were randomly assigned three treatment conditions: (1) etching for 90 seconds with 5% hydrofluoric acid gel, (2) sandblasting (110-micron Al2O3), and (3) tribochemical silica coating. All samples were silanated following the surface treatment. The luting cements were bonded to In-Ceram specimens using Teflon tubes. All samples were thermocycled for 5,000 cycles altering between 5 and 55 degrees C with 30-second dwell times. The shear bond strength values were measured in a universal testing machine with a cross-head speed of 1 mm/min. Analysis of variance was used to analyze data. RESULTS: The mean bond strengths varied between 1.2 and 24.7 MPa. CONCLUSION: Shear bond strength of compomer cement following tribochemical silica coating was significantly lower in comparison to resin cements. Luting of In-Ceram with various resins provided varying degrees of bond strengths that were significantly increased by the tribochemical silica-coating system.

Aluminum Oxide↗
PubMedDate not supplied

Dimensional accuracy and retentive strength of a retrievable cement-retained implant-supported prosthesis.

The purpose of this research project was to compare the fit of a retrievable cement-retained implant-supported framework to that of a traditional wax and cast, screw-retained framework and to test the strength of the cemented restoration. Ten telescopic frameworks were luted to gold cylinders with a bis-GMA resin cement. The control group consisted of 10 frameworks fabricated with traditional wax and casting techniques directly to the gold cylinders. Frameworks were analyzed for distortion in the z-axis using scanning electron microscopy and a single screw test. Results demonstrated that the retrievable cement-retained group had a decreased gap distance and improved angular distortion (statistical significance P < .01) compared to the control group. Retentive strength measurements for the cement-retained group with a direct pull-out test revealed a mean pull-out force of 65.7 kg. Three of the 5 samples surpassed the tensile strength of the gold retaining screws (76 kg). Cement-retained restorations demonstrated superior fit in the z-axis and angular distortion compared to traditional wax and cast screw-retained frameworks. Retentive tests support a simplified technique of clinically luting telescopic implant-supported frameworks with adequate retentive strength.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1999

[Color differences between a resin cement and try-in paste].

OBJECTIVE: This study was to measure the color coincidence and difference of resin cement and its try-in paste. METHODS: 3 shades of a resin cement and its try-in paste were measured and analyzed by CIE L*a*b* on a reflection spectrophotometer. RESULTS: For shade 200, vulue of delta E* was less 1.4 in comparison between try-in paste and self-cured resin. CONCLUSION: The try-in paste of shade 200 matched the self-cured resin cement very well, but the try-in paste was lighter and more yellow than the light-cured resin cement. The resin cement of shade 100 was darker and more yellow than try-in paste; resin cement of shade 300 was lighter and more yellow than try-in paste.

Color↗
PubMed2003

Bond strength of glass-ionomer cements to caries-affected dentin.

PURPOSE: The aim of this study was to assess the tensile bond strength of a resin-modified glass-ionomer cement (a: Fuji II LC) and three traditional glass-ionomer cements (b: Ketac-fil; c: Ketac Molar; d: Fuji IX) to caries-affected dentin. MATERIALS AND METHODS: Forty human permanent molars with occlusal caries in dentin were selected, embedded in polyester resin, and ground until the carious dentin was exposed. Infected dentin was removed with curettes according to the atraumatic restorative technique (ART), and the tooth surface was smoothed with SiC paper. A bonding site, limited to 3 mm in diameter, was treated with polyacrylic acid for 10 s. After surface treatment, an inverted glass-ionomer cone was prepared for each specimen, using a split bisected Teflon matrix. The cones were immediately protected with a thin layer of nail varnish or bonding agent. Specimens were stored in distilled water at 37 degrees C for 24 h, and then bond strength to failure was tested. RESULTS: The mean (SD) bond strengths in MPa were: a: 8.33 (2.35); b: 2.46 (1.60); c: 0.83 (1.18), and d: 1.45 (1.70). The data were analyzed using ANOVA and Tukey statistical tests. Fuji II LC, a resin-modified glass-ionomer cement, showed higher bond strength values and was statistically superior to the other groups, containing traditional glass ionomer cements (p < 0.05). CONCLUSION: Findings showed that the traditional glass-ionomer cements tested in this study had lower mean bond strength values to caries-affected dentin than did the resin-modified glass-ionomer cement.

Acid Etching, Dental↗
PubMedDate not supplied

Bond strength between polymer resin-based cement and porcelain-dentin surfaces: influence of polymerization mode and early cyclic loading.

PURPOSE: The objective of this study was to verify the influence of resin cement polymerization mode and early cyclic loading on the bond strength of porcelain-dentin specimens. MATERIALS AND METHODS: Two cementation systems, Choice/One-Step and RelyX ARC/Single Bond, were tested. Porcelain truncated cones were bonded into cavities prepared in sections of bovine root dentin. Each system was tested with the resin cement in dual-cure and self-cure mode (with and without photoactivation, respectively). Half of the specimens were load cycled 15 minutes after cement mixing (60 N, 20 times). The other half were not submitted to mechanical loading (control). After 24-hour storage in distilled water (37 degrees C), the extrusion shear test was performed. Data were analyzed by three-way ANOVA. RESULTS: With both systems, some specimens built with the cement in self-cure mode debonded during cyclic loading (RelyX ARC/Single Bond 47%; Choice/One-Step 13%). No significant system effects were detected. Mean bond strength under the dual-cure mode (13.4 MPa, SD 3.6) was significantly higher than the corresponding mean for the self-cured specimens (5.7 MPa, SD 2.6). No reduction in bond strength was observed for the specimens that survived the early cyclic loading. CONCLUSION: Resin cements in dual-cure mode presented higher bond strengths than self-cured materials. Early load cycling caused debonding of some self-cured specimens. However, the bond strength of the survivor specimens was not affected by load cycling.

Analysis of Variance↗
PubMedDate not supplied

Influence of timing of coronal preparation on retention of cemented cast posts and cores.

PURPOSE: This study investigated the effect of coronal preparation by high-speed handpiece on the retention of cemented cast posts and cores. MATERIALS AND METHODS: Cast posts and cores were fabricated for 90 extracted single-rooted human teeth cemented with zinc-phosphate cement and randomly divided into six groups of 15 specimens each. The six groups were matched randomly two by two, such that one of each of the matched groups was subjected to a 4-minute period of high-speed preparation of the cores. Castings from the first pair (1 and 2) were subjected to an axially directed removal force using a universal testing machine 15 minutes from the start of cement mixing; castings from the second (3 and 4) and third (5 and 6) pairs were tested at 1 hour and 24 hours, respectively, having been stored in water at 37 degrees C for the waiting periods. The forces required for dislodgment of posts from their prepared spaces were recorded. Data were statistically analyzed using two- and one-way ANOVA and the Student's t test. RESULTS: The results showed increased mean retentive strengths of posts as the time to testing increased for both unprepared and prepared groups. Significantly higher mean retentive strengths of posts were recorded for unprepared compared to prepared groups tested at 15 minutes and 1 hour after cementation. CONCLUSION: High-speed preparation had a significant negative effect on the retentive strengths of posts tested at 15 minutes and 1 hour after cementation, but not on those tested at 24 hours.

Analysis of Variance↗
PubMedDate not supplied

Shear resistance of silver- and stainless steel-reinforced glass-ionomer cements bonded to enamel and dentin.

The shear bond strength to human dentin and enamel was evaluated for four glass-ionomer cements: an experimental stainless steel-reinforced glass-ionomer cement, two commercially available silver-reinforced cements, and a conventional glass-ionomer cement. Bonded specimens were stored in distilled water for 7 days during which time they were subjected to thermocycling in water baths at 5 degrees C and 55 degrees C for a 1-minute dwell time per bath and 1500 cycles. Specimens were then shear tested. The experimental stainless steel-reinforced glass-ionomer cement had a significantly higher bond strength to enamel (P < .01) and dentin (P < .05) than did the commercially available cements.

Analysis of Variance↗
PubMed2004

Contained femoral defects: biomechanical analysis of pin augmentation in cement.

Although in the proximal tibia the need for pin augmentation of cemented giant cell tumor defects depends on whether the defect is contained, there is controversy regarding the role for pins in the distal femur. The current study investigated whether Steinmann pin augmentation offers biomechanical advantages in cement reconstruction of contained defects of the lateral femoral condyle. Twelve pairs of human femurs were used. They were tested either with the bone intact, with a standardized contained defect in the lateral condyle, with a defect repaired with cement alone, and with a defect repaired with pins in the cement. Intact specimens had significantly higher load to failure than specimens with a defect. In the repaired specimens there were no significant differences in stiffness, peak load to failure, and energy to failure between the specimens repaired with just cement or augmented with pins. This study did not show any significant biomechanical advantage of this configuration of Steinmann pin reinforcement in cement for contained defects of the lateral femoral condyle.

Biomechanical Phenomena↗
PubMedDate not supplied

Correlation between microleakage and cement thickness in three Class II inlay ceramic systems.

The objectives of this study include comparing the cement thickness and microleakage of Class II ceramic inlays built with three ceramic systems and verifying whether there was a correlation between those two variables. The ceramic systems used include: 1) Heat-pressed (IPS-Empress); 2) CAD-CAM (CEREC 2) and 3) Sintered (Colorlogic). Standardized MOD Class II inlay cavities with one proximal box extending below and the other extending above the cement-enamel junction (CEJ) were prepared in 30 extracted human molars and randomly assigned to three groups. The ceramic inlays were constructed according to manufacturer's instructions and cemented using a dual-cure resin cement (Variolink II). All teeth were mechanically cycled (100,000 cycles, 78N) and thermocycled (700 cycles, 5 degrees C-55 degrees C). After immersion in silver nitrate, the inlays were sectioned mesial-distally and evaluated with an optical microscope (40x). The cement thickness obtained by the Colorlogic system (enamel: 113 +/- 25 microm; dentin: 118 +/- 23 microm) was significantly higher than that obtained by CEREC (enamel: 78 +/- 14 microm; dentin: 87 +/- 13 microm) and Empress (enamel: 65 +/- 15 microm; dentin: 89 +/- 14 microm). Regarding dye penetration, there was no statistical difference among the three ceramic systems in enamel. At the dentin margins, the Colorlogic system resulted in a significantly higher penetration depth compared to CEREC and Empress, which had similar average values. No correlation was found between cement thickness and microleakage either in enamel or dentin for any of the ceramic systems.

Aluminum Silicates↗
PubMedDate not supplied

A study of the physical and chemical properties of four resin composite luting cements.

PURPOSE: This study evaluated the surface microhardness and flexural and compressive strengths of five luting cements and compared the degree of conversion of dual and autopolymerized forms of four resin-based luting cements. MATERIALS AND METHODS: Four resin composite luting cements-Panavia F, Variolink 2, RelyX Unicem Applicap, and RelyX ARC-and a polycarboxylate cement (Durelon, control group) were used in three-point bending, compression, and Vickers hardness tests following water storage for 1 week. Resin composite cements were additionally investigated with both dual and autopolymerization techniques under Fourier transformed infrared spectroscopy. Differences were analyzed using one-way ANOVA. RESULTS: The highest flexural strengths were obtained with Variolink 2 (90 MPa, SD 22), whereas the lowest were observed with Durelon (28 MPa, SD 4). RelyX Unicem showed the highest hardness values (44 HV, SD 5), whereas Variolink 2 gave the lowest (32 HV, SD 6). The highest compressive strengths were obtained with RelyX Unicem (145 MPa, SD 32), whereas the lowest were observed with Durelon (41 MPa, SD 17). For both dual and autopolymerized groups, RelyX ARC showed the highest degrees of conversion (81% and 61%, respectively) and RelyX Unicem had the lowest (56% and 26%, respectively). CONCLUSION: Resin composite luting cements of similar chemical characterizations differed in their physical properties, and polymerization method influenced their degree of conversion.

Analysis of Variance↗
PubMed2004

Effect of ceramic surface treatment on the microtensile bond strength between a resin cement and an alumina-based ceramic.

PURPOSE: The objective of this study was to test the following hypothesis: the silica coating on ceramic surface increases the bond strength of resin cement to a ceramic. MATERIALS AND METHODS: In-Ceram Alumina blocks were made and the ceramic surface was treated: G1--sand-blasting with 110-microm aluminum oxide particles; G2--Rocatec System: tribochemical silica coating (Rocatec-Pre powder + Rocatec-Plus powder + Rocatec-Sil); G3--CoJet System: silica coating (CoJet-Sand) + ESPE-Sil. The ceramic blocks were cemented to composite blocks with Panavia F resin cement (under a load of 750 g/1 min). The cemented blocks were stored in distilled water at 37 degrees C for 7 days and sectioned along the x and y axes with a diamond disk. Samples with an adhesive area of ca 0.8 mm2 (n = 45) were obtained. The samples were attached to an adapted device for the microtensile test, which was performed in a universal testing machine (EMIC) at a crosshead speed of 1 mm/min. RESULTS: The obtained results were submitted to ANOVA and Tukey's test. Mean values of tensile strength (MPa) and standard deviation values were: (G1) 16.8+/-3.2; (G2) 30.6+/-4.5; (G3) 33.0+/-5.0. G2 and G3 presented greater tensile strength than G1. There was no significant difference between G2 and G3. All the failures took place at the ceramic/resin cement interface. CONCLUSION: The silica coating (Rocatec or CoJet systems) of the ceramic surface increased the bond strength between the Panavia F resin cement and alumina-based ceramic.

Analysis of Variance↗
PubMedDate not supplied

Assessing the tooth-restoration interface wear resistance of two cementation techniques: effect of a surface sealant.

This study compared (1) the tooth-restoration interface width of conventional and "resin coating" cementation techniques, (2) the toothbrushing wear resistance of the two interfaces and (3) this study evaluated the influence of a restoration surface sealing on toothbrush wear resistance on both cementation technique interfaces. Mid-coronal buccal surfaces of 40 bovine teeth were ground to obtain a flat enamel surface. For each specimen, a 3 mm x 4 mm x 3 mm dimension rectangular cavity was prepared. The teeth were divided into four groups. Two groups (RC) received a "resin coating" (ED Primer + Tetric Flow) prior to cementation. The remaining two groups (NC) served as non-coated groups. All teeth were restored with composite inlays (Z250) fabricated by the indirect method and were cemented with dual cure resin cement (Panavia F). After finishing the margins, one group from each of the cementation techniques (RC+S and NC+S) had the tooth-restoration interface protected with a restoration surface sealant (Biscover). The specimens were subjected to 100,000 brushing abrasion cycles. The tooth-restoration width was obtained using a Hommel Tester T 1000-basic profilometer and Turbo Datawin NT 1.34 Software (microm). The interface wear (vertical loss/microm and area/microm2) was calculated with Image Tool 3.0 Software. Data were analyzed with Student t-test, one-way analysis of variance and Tukey test (alpha=0.05). Mean interface width for the NC group was 67 microm and 72 microm for the RC group. The student t-test showed no significant differences between groups (p=0.53). ANOVA showed significant differences (p<0.01) in vertical loss among groups (NC: 49.30 microm; NC+S: 7.90 microm; RC: 27.15 microm; RC+S: 4.74 microm). Also, ANOVA showed significant differences (p<0.01) in worn areas among groups (NC: 2,008 microm2; NC+S: 128 microm2; RC: 1,580 microm2 and RC+S: 88 microm2). No differences were found in tooth-restoration interface width and worn area between conventional and "resin coating" techniques. "Resin coating" interface presented reduced vertical loss. Restoration surface sealing provided reduced wear in tooth-restoration interface for both techniques.

Acrylates↗
PubMed2006

[Retention of fiber posts dependent on different resin cements].

Tooth-coloured adhesive inserted fiber posts are used to restore endodontically treated teeth. In this investigation, the tensile bond strength of two different fiber posts systems (ER DentinPost and DT Light Post) in combination with five different resin cements was tested. The posts were inserted into artificial root canals in bovine dentin using Clearfil Core, RelyX Unicem, Panavia 21ex, Panavia F2.0 und Calibra. Titan posts (ER-Kopfstift), inserted with zincphosphate cement served as control group. ER DentinPost inserted with Clearfil Core had significantly higher tensile bond strengths than in combination with Panavia F2.0 (221.70 +/- 17.99 N) or Calibra (212.37 +/- 45.20 N). DT Light Post in combination with Calibra (338.20 +/- 46.40 N), Panavia F2.0 (321.69 +/- 40.11 N) and Panavia 21ex (290.41 +/- 55.28 N) showed significantly higher tensile bond strengths compared to adhesive cementation with RelyX Unicem (211.57 +/- 32.35 N) and Clearfil Core (131.67 +/- 51.72 N). The tensile bond strength of the control group was in the upper third of the values (315.43 +/- 51.38 N). Optical analysis of the post surface after decementation demonstrated in all cases adhesive-cohesive mixed fractures. The adhesion of resin cement to the fiber posts and resin cement to root canal dentin is influenced by different factors. The combination of fiber post systems with the type of resin cement has a great influence on the tensile bond strength.

Animals↗