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At least 145 records · Page 8Linked to original sources

Silane coupling agents in stainless steel and polymethyl methacrylate systems.

Smooth stainless steel rods coated with silanes were embedded in acrylic resin dough. The strength of the bond between treated rods and polymerized resin was improved compared with that found in the untreated rods under all conditions of the tests. The strength increased with age when specimens were left in air; immersion in water lessened the increase in strength.

Acrylic Resins↗

Pulmonary embolism of polymethyl methacrylate during percutaneous vertebroplasty and kyphoplasty.

OBJECTIVE: The purpose of this study was to determine the frequency, radiographic findings, and clinical significance of a pulmonary embolism of cement occurring during percutaneous vertebroplasty or kyphoplasty as detected on conventional chest radiography. MATERIALS AND METHODS: Chest radiographs were obtained after 69 percutaneous vertebroplasty procedures in 64 patients. Chest radiographs were reviewed retrospectively for the presence of pulmonary emboli of cement, and findings were assessed. The frequency was calculated from the cases treated. Medical records were reviewed for procedure-related complications. RESULTS: The emboli of cement were noted radiographically in three (4.6%) of 65 procedures performed in our institution. All patients with cement emboli had multiple myeloma. The chest radiographic findings were multiple radiographically dense opacities with a tubular and branching shape that were scattered sporadically or distributed diffusely throughout the lungs. All patients with cement pulmonary embolism remained asymptomatic. A correlation of embolism of cement to lungs was found with paravertebral venous cement leak (p < 0.001) but not with the number of vertebral bodies treated (p = 0.185) or with the type of procedure performed-kyphoplasty versus vertebroplasty (p = 0.98). CONCLUSION: Pulmonary embolism of cement is seen in 4.6% of patients after percutaneous vertebroplasty or kyphoplasty. The characteristic radiographic findings should be recognized by radiologists.

Bone Cements↗

Impact strength of denture polymethyl methacrylate reinforced with continuous glass fibers or metal wire.

The impact strength of heat-cured acrylic resin test specimens that had been reinforced in various ways was compared in this study. Ten rectangular test specimens were fabricated for each test group. The strengtheners included 1.0-mm-diameter steel wire and continuous E-glass fibers. Both notched and unnotched test specimens were tested in a Charpy-type impact test. In a further analysis the concentration of glass fibers in the test specimens was determined and plotted against the impact strength of the test specimens. The results showed that, compared with the unreinforced specimens, both types of reinforcement increased the impact strength of the test specimens considerably (p < 0.001). There was no clear difference between the mean impact strength value of the test specimens reinforced with metal wire and that of the specimens reinforced with glass fiber. The correlation coefficient between the fiber concentration of the test specimens and their impact strength was 0.818 (p < 0.005). Specimens with fiber concentrations greater than 25 wt% yielded to the higher impact strength more readily than those with metal wire reinforcement did.

Dental Stress Analysis↗

In vivo characterization of indomethacin magnetic polymethyl methacrylate nanoparticles.

The in vivo magnet responsiveness and kinetics of distribution of indomethacin entrapped in a magnetic and plain carrier were characterized by rat tail model and periodic monitoring of drug concentration in various visceral organs after intraarterial and intravenous administration respectively. Up to 60 min post injection time 60-fold higher concentrations could be achieved in tail target segment which resulted in considerably reduced drug concentration in other organs as evinced by data from control rats. Following normal administration (no magnetic field applied) the drug concentration was higher in the liver and spleen where endocytosis and phagocytosis occur. The magnetic nanoparticle of indomethacin holds promise for selective targeting under magnetic field of 8000 Oe strength.

Animals↗

[Autoradiographic determinations of carbon-14-labeled monomers and residual monomers in the tissues of Wistar rats after implantation of cold-polymerizing polymethyl methacrylate (bone cement) (author's transl)].

Self-setting acrylics, named bone cement, are taken for the reconstruction of bone defects, for the fixation of endothesis and fractures. A disadvantage of these rapid-cure acrylic compounds is the toxicity of its monomer. Infraredspectrographic measurements showed an absolute content of 12,3 per cent monomer in an acrylic-resin-compound-implant. In order to perseive the incorporation of the diffused monomer after implantation of bone cement in rats, the monomer were marked with 14C (radioactive carbon). The autoradiographic examination revealed the excretion of the marked monomer in the urine and an accumulation in kidney, liver and lungs. The results were demonstrated.

Acrylic Resins↗

Hydrolysed microspheres from cross-linked polymethyl methacrylate (Hydrogel). A new embolic material for interventional neuroradiology.

Highly hydrophilic, perfectly smooth and spherical microspheres have been synthetized. These non-biodegradable microspheres absorb water in varying degrees and can be injected easily through microcatheters due to their slippery and compressible characteristics. The material was successfully used for embolization of 4 vascular intracranial tumours and 2 spinal vascular lesions in the cervical region, by superselective delivery. Histopathology confirmed absolute inertness of the microspheres.

Adult↗

[Addition of gentamicine to polymethyl methacrylate for therapy of infectious bone diseases. Expeimental in vivo tests].

In experimental in vivo tests the therapeutic effect of Gentamicin added to Palacos is detected in a standardized osteomyelitic infection caused by Staph. aureus haemolyticus. The number of germ populations is reduced significantly by the antibiotic which is released in a microbiologically active concentration. On the other hand the number of germ populations in control trials (without adding an antibiotic) is remaining on a high level. During the time of the tests the appearance of other bacterial is registrated.

Animals↗