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The effect of etchant and cement age on the adhesion of resin composite to conventional and resin-modified glass-ionomer cements.

The effects of etching with maleic or phosphoric acid on the adhesion of resin composite to resin-modified glass-ionomer cement restorative materials were evaluated through a shear bond test. These effects were determined with both recently set and aged cement. For the three resin-modified materials tested, compared to no etching, the two etchants improved or did not affect the adhesion of resin composite, regardless of the age of the cement. For a chemically cured material, included in the study as a control, the same effects were observed, except that etching of the recently set cement with maleic acid was detrimental to adhesion.

Acid Etching, Dental↗

Adhesive cements and cementation.

Luting cements are a critical, but weak, link between fixed prostheses and their supporting tooth structures. Luting cements have relatively poor physical properties compared to bulk restorative filling materials, but they must fulfill an additional series of requirements such as low film thickness. As they have a wide variety of applications, no single material can be recommended for all clinical situations. This paper reviews the properties required of luting agents, the currently available material classes of luting agents and clinical cementation procedures, and makes suggestions for specific clinical situations.

Cementation↗

Optimal cement space for resin luting cements.

Stainless steel dies, simulating 0 to 80 microns of die spacing, were seated into a machined brass crown with Phosphacap, Panavia EX, and C & B Metabond. The seating discrepancy after 60 seconds was measured to determine the optimal cement space for best seating for each agent. The most complete seating for crowns luted with zinc phosphate cement was observed when at least 40 microns of cement space was provided. C & B Metabond and Panavia required 30 microns of die spacing.

Analysis of Variance↗

Improved cortical histology after cementation with a new MMA-DMA-IBMA bone cement: an animal study.

The histological response of bone to inert bone wax, conventional polymethylmethacrylate (PMMA), and a new formulation of bone cement, methylmethacrylate/n-decylmethacrylate/isobornylmethacrylate (MMA/DMA/IBMA) was investigated in canine tibial diaphysis. The new formulation of cement is characterized by a reduced exothermic temperature at curing and reduced leakage of chemicals to the adjacent bone. In comparison with bone wax, the MMA/DMA/IBMA bone cement did not differ significantly with respect to periosteal apposition and bone remodeling, although a tendency to inhibit the biological response was encountered. The MMA/DMA/IBMA was clearly superior to PMMA bone cement in respect to both bone necrosis and repair, as well as bone remodeling.

Animals↗

[Glass ionomer cements as orthodontic bracket adhesives. An in vitro study with 4 glass ionomer cements (GIC) and 2 conventional orthodontic bracket adhesives as the comparative group].

240 orthodontic brackets were bonded to buccal surfaces of bovine teeth. As bonding material we used four glass ionomer cements without etching and two normal orthodontic bracket bonding materials with etching of enamel. Brackets of group 1 were tested with a material testing machine for shear and tensile strength after ten minutes. Brackets of group 2, 3 and 4 were tested after one day, 28 days and 98 days, respectively. In the average the bonding strength of glass ionomer cements was 50% less than the bonding strength of the comparison group with etching. The fracture of the bonding took place to 80% between the mesh base and the glass ionomer cements. Defects of the enamel surface were never observed. The bonding between mesh-base and glass ionomer cements has to be improved before the use of this bonding material can be recommended for the use in a busy practice.

Animals↗

Rapid chondrolysis after an intra-articular leak of bone cement in treatment of a benign acetabular subchondral cyst: an unusual complication of percutaneous injection of acrylic cement.

Percutaneous injection of methylmethacrylate is now increasingly employed to treat bone lesions, both malignant and benign. However, the risks of this procedure are still to be fully established. In this report, we describe a case of rapid chondrolysis appearing after the intra-articular leakage of cement during injection of an acetabular subchondral cyst, resulting in hip replacement. Although the mechanism of such chondrolysis is unknown, this event suggests a chondrolytic effect of the acrylic cement. Thus, it is essential to systematically search for the presence of an intra-articular passage before injecting bone cement into a peri-articular cyst. This unusual complication highlights the need for rigorous evaluation of the benefits and risks of percutaneous injection of acrylic cement in the treatment of benign lesions, especially close to an articulation.

Acetabulum↗

The performance of three vacuum-mixing cement guns--a comparison of the fatigue properties of simplex P cement.

We tested three commercially available cement-mixing systems (Howmedica, Summit and Stryker). After mixing the cement was allowed to cure in metal moulds under standard conditions. Sixty-nine cement blocks were produced. The fatigue behavior of the blocks was tested until failure. A wide scattering of results was observed in all the three systems. Uneven mixing of the polymer and monomer was observed in the Howmedica system. A significantly stronger cement (P=0.018) was produced with the Stryker system.

Bone Cements↗

Preparation and characterization of a novel bioactive bone cement: glass based nanoscale hydroxyapatite bone cement.

A novel type of glass-based nanoscale hydorxypatite (HAP) bioactive bone cement (designed as GBNHAPC) was synthesized by adding nanoscale hydroxyapatite (HAP) crystalline (20-40 nm), into the self-setting glass-based bone cement (GBC). The inhibition rate of nanoscale HAP and micron HAP on osteosarcoma U2-OS cells was examined. The effects of nanoscale HAP on the crystal phase, microstructure and compressive strength of GBNHAPC were studied respectively. It was concluded that nanoscale HAP could inhibit the cell proliferation, while micron HAP could not, and that nanoscale HAP could be dispersed in the cement evenly and the morphology did not change significantly after a longer immersion time. XRD and FTIR results show nanoscale HAP did not affect the setting reaction of the cement. Furthermore, GBNHAPC had a higher compressive strength (92 MPa) than GBC. It was believed that GBNHAPC might be a desirable biomaterial that could not only fill bone defects but also inhibit cancer cell growth.

Bone Cements↗

Shape optimal design of the stem of a cemented hip prosthesis to minimize stress concentration in the cement layer.

An optimal shape of the metal stem of a cemented total hip prosthesis minimizing stress concentration in the cement layer was searched for. A gradient projection method of numerical optimization and a finite element method of stress analysis were employed. A two-dimensional model of the femoral part of a total hip prosthesis was derived equivalent to a simplified three-dimensional axisymmetric model. The result of the stress analysis of the two-dimensional model compared favorably with that of the three-dimensional axisymmetric model. Using this two-dimensional model, an optimal shape of the stem, minimizing stress concentration in the cement layer, was obtained by a gradient projection method and the shape was checked again by the three-dimensional finite element analysis. The resulting optimal shape of the stem profile was in good agreement with conventional ones, except in the proximal region where a significant amount of stress reduction in the cement layer was achieved by tapering the stem to the limit that the stem still could withstand the increased stem stress.

Bone Cements↗

Tensile fatigue of 4-META cement bonding three base metal alloys to enamel and comparison to other resin cements.

The tensile median fatigue limits and fracture mode of 4-META cement were evaluated after bonding Ni-Cr, Ni-Cr-Be, and Co-Cr alloys to enamel. Alloy surfaces, 6 mm in diameter, were grit blasted with 50 microns Al2O3 and cemented to etched bovine enamel under a 2 kg load. Samples were cycled in tension to failure or 10(6) cycles at 5 Hz in Ringer's solution at 37 degrees C. Two-point strategy was used to determine median fatigue limits (S50). Fracture modes were evaluated by SEM on samples failing before 10(6) cycles. Results indicated differences between all sample groups where S50 (Ni-Cr-Be) > S50 (Co-Cr) > S50 (Ni-Cr). Failure analysis revealed mixed cohesive fractures near both interfaces with small areas of delamination within the cement. Comparison to reported median fatigue limits of two commercially available cements were discussed.

Acrylic Resins↗

Fifteen-year survivorship of a collarless, cemented, normalized femoral stem in primary hybrid total hip arthroplasty with a modified third-generation cement technique.

This prospective review aimed to evaluate 15-year survivorship of the collarless, third-generation cemented, normalized, Omnifit (Osteonics, Allendale, NJ) femoral stem in hybrid total hip arthroplasty (THA). Between January 1986 and June 1990, a single surgeon prospectively implanted 250 consecutive hybrid THAs (215 patients) using a modified third-generation cement technique in selected patients. A Harris-Galante (I or II) (Zimmer, Warsaw, IN) cementless shell with modular polyethylene (4150 resin) liners gamma-sterilized in air were implanted. Kaplan-Meier survivorship of the femoral or acetabular component with mechanical failure (revision for aseptic loosening) as the end-point was 100% +/- 0% at 15 years. Wear couple exchange and bone grafting was performed in 1 case (0.4%) for progressive acetabular osteolysis. This report supports femoral component centralization and good cement mantle to ensure durability of the collarless, cemented, normalized femoral stem with a surface roughness of 30-40 microinches.

Aged↗

Prechilling and vacuum mixing not suitable for all bone cements. Handling characteristics and exotherms of bone cements.

Nine bone cements were tested for handling characteristics, intrusion, doughing time, setting time, and exothermic temperature. Comparative studies were made of manual mixing and vacuum mixing of cement components stored at room temperature or chilled to 5 degrees C. Vacuum mixing of cement packages stored at room temperature was inapplicable except for the low-viscosity brands, as the cements became too viscous to mold test specimens. Prechilling and vacuum mixing prolonged the setting time and preserved a lower viscosity during the handling period. Palacos R and Palacos G were most suitable for this method, whereas a considerable increase in exothermic temperature was experienced with the other brands. The method might, however, be considered for Zimmer and Cerafix also, as the exotherm was of the same magnitude as for Palacos brands.

Bone Cements↗

A novel transducer for the measurement of cement-prosthesis interface forces in cemented orthopaedic devices.

When a cemented orthopaedic device is being investigated there is a need to estimate the forces at the cement-prosthesis interface. For this reason a miniature transducer was developed that could be included inside the surface of most prostheses. A load cell (based on a piezoelectric sensor) and the required accessories and amplification were custom designed and built. The present work describes the validation that was performed on the piezo sensors alone, when mounted on a simplified structure, and when applied to a hip stem.Linearity, repeatability, reproducibility, and sensibility to shear and axial eccentric loads were tested, yielding satisfactory results. The repeatability on the same sensor was found to be good while reproducibility between sensors was lower. Thus, each sensor was calibrated separately with a second order relationship. Sensitivity to shear and eccentric loads was very low. The overall accuracy of the load cell (including non-linearity, and signal drift) was of the order of about 1%.A hip stem instrumented with four such sensors was successfully implanted in a composite femur, yielding meaningful readouts.Thus, this type of sensor can readily be used to assess the cement-prosthesis interface forces in cemented devices.

Biomechanical Phenomena↗

Distal cement mantle thickness with a triangular distal centralizer inserted into the stem tip in cemented total hip arthroplasty.

Fifty-seven hips undergoing a primary cemented total hip arthroplasty with use of a triangular distal centralizer inserted into the stem tip were investigated, with a special focus on distal cement mantle thickness. The subjects were 43 women and 3 men. When evaluated on conventional anteroposterior and lateral radiographs, the relative incidence of thin cement mantles in zones 3 or 5 owing to the distal centralizer was 15.8% (9 hips). Unsatisfactory findings were that the distal centralizer and distal part of the stem shifted to the cortex in 7 hips and bent or failed at the inserted site in 2 hips. There is risk of generating a thin cement mantle with use of the triangular centralizer and its insertion into the stem tip.

Adult↗

[Migration analysis of cemented Müller polyethylene acetabular cups versus cement-free Zweymüller screw-attached acetabular cups].

OBJECTIVE: Is the cementless Zweymüller hip cup superior to the cemented Müller cup? METHOD: This article presents a radiographic analysis of 25 cemented Müller acetabular cups versus 22 cementless Zweymüller cups using the Einbildröntgenanalyse (EBRA), a software tool for radiographic measurement of acetabular cup migration. In addition, we determined the effects of the cup anteversion and inclination, the polyethylene wear, the lateral bone coverage of the acetabular cup, the position of the center of rotation, and individual factors on the incidence of cup migration. RESULTS: The incidence of cup migration was 64% in the cementless group and 48% in the cemented group after a mean follow-up of 6 years. The average migration rate was 0.33 mm/a for cementless Zweymüller cups and 0.38 mm/a for cemented Müller cups. Cup anteversion and inclination showed no effect on the incidence of cup migration. The combination metal-polyethylene (0.17 mm per year) demonstrated a significantly higher wear rate in comparison to the ceramic-polyethylene combination (0.11 mm per year). Incompletely lateral covered cups demonstrated a significantly higher incidence of cup migration. Cranial or medial deviations of the center of rotation up to 5 mm are tolerable, in contrast to caudal or lateral deviations that lead to a significantly higher incidence of cup migration. CONCLUSION: The superiority of the cementless Zweymüller cup was not observed. We recommend a complete lateral bone coverage of the hip cup. Cranial and medial deviations of the center of rotation up to 5 mm are tolerable. In the present study the polyethylene wear of the ceramic-polyethylene combination was significantly less as compared with the metal-polyethylene combination.

Acetabulum↗

Bone cement ossiculoplasty: incus to stapes versus malleus to stapes cement bridge.

OBJECTIVE: In this study, our purpose was to evaluate results of our experience with bone cement repair of ossicular discontinuity between the incus and stapes and between the malleus and stapes. METHODS: Medical records of patients who underwent surgery for chronic otitis media between March 2000 and December 2002 were evaluated retrospectively. Fifty-seven patients who underwent bone cement ossiculoplasty and had appropriate follow-up data were included in the study. Bone cement reconstruction of the ossicular chain was performed 1) from incus to stapes (I-S) in the absence of long arm or lenticular process of the incus and 2) from malleus to stapes (M-S) in the absence of the incus. The clinical data of the patients were evaluated by otoscopic examination and audiometry. RESULTS: The graft take rate was 84.1%. I-S procedure was performed in 42 and M-S in 8 patients. Pre- and postoperative PTAs of all patients were compared, which showed a significant improvement in air PTA (p < 0.001) while bone PTA did not change (p > 0.05). In I-S and M-S groups, successful hearing restoration could be achieved in 78.6.1% and 87.5% of the patients, respectively. Hearing results of different aural pathologies (chronic otitis media and conductive hearing loss) and surgeries (tympanotomy and tympanoplasty with or without mastoidectomy) were not significantly different (p > 0.05). CONCLUSION: Bone cement ossiculoplasty offers cost effective and significant improvement in conductive hearing loss.

Adult↗

Total hip replacement with insertion of an acetabular component without cement and a femoral component with cement. Four to seven-year results.

One hundred and fifty-three so-called hybrid total hip replacements were performed in 142 patients from 1985 to 1987 at Rush-Presbyterian-St. Luke's Medical Center. A hemispherical porous-coated acetabular component was inserted without cement and was fixed with screws, and a femoral stem was inserted with the use of so-called third-generation cementing techniques. The average age of the patients at the time of the operation was sixty-seven years (range, thirty-nine to eighty-five years). The average preoperative Harris hip score was 46 points (range, 9 to 73 points). One hundred and eleven patients (120 hips) were available for clinical review; 100 of these patients (109 hips) had a complete set of radiographs available. The average Harris hip score was 86 points (range, 29 to 100 points) at the time of follow-up (average duration, sixty-two months; range, forty-eight to eighty-five months). There was progressive migration of one cup (1 per cent); another cup migrated one centimeter in the first two years after the operation, with no additional migration evident after that time. The remaining acetabular components were stable. Two femoral components (2 per cent) were determined to be definitely loose. The remaining femoral components were stable. This population of patients had a good result after so-called hybrid total hip replacement with insertion of a porous-coated acetabular component without cement and a femoral component with cement for the reconstruction of a painful hip.

Adult↗