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PubMed2005

Static immersion and irritation tests of dental metal-ceramic alloys.

The expansion of the European Union is bringing new types of metal-ceramic alloys to the market, i.e. alloys probably unknown in Western-European dentistry. The aim of this study was to investigate recent developments and "classic" alloy compositions (one iron and two cobalt alloys, unalloyed titanium and an experimental titanium-zirconium alloy, and one gold alloy containing copper and zinc). The alloys and titanium were subject to static immersion in a 0.1 mol l(-1) solution of saline lactic acid before and after oxidation, hence simulating the temperature cycles for the application of ceramic to metal. The greatest amounts of released metal ions were found in the electrolytes of the oxidized gold alloy and of a cobalt alloy not exposed to high-temperature oxidation. Corrosion of the titanium and alloy surfaces was related to the condition of the specimen. The irritation potentials of some metal ions found in the electrolyte were investigated by performing the hen's egg test-chorio-allantoic membrane (HET-CAM) procedure with 1 mmol l(-1) solutions of Ce(3+), Co(2+), Cu(2+), Zn(2+), Fe(2+), and Ti(4+) ions. The irritation potential of the electrolyte of the oxidized gold alloy with a high concentration of metal elements was also investigated. Of these solutions, only the 1 mmol l(-1) Cu(2+) solution was graded as slightly irritating.

Animals↗
PubMed2003

Colorimetric evaluation of the influence of five different restorative materials on the color of veneered densely sintered alumina.

PURPOSE: Since the introduction of densely sintered alumina ceramic material in prosthetic dentistry for the fabrication of all-ceramic crowns, no scientific data have been presented on the color of these restorations in combination with different restorative materials. The purpose of this in vitro study was to evaluate the influence of five different restorative materials used for implant abutments or posts and cores on the color of veneered densely sintered alumina. MATERIALS AND METHODS: Sixty discs, 0.6 mm in thickness and 10 mm in diameter, were made out of densely sintered alumina ceramic material (Procera, Nobel Biocare, Gothenburg, Sweden) and veneered using feldspathic porcelain (AllCeram, Ducera, Rosbach, Germany) for a total thickness of 2 mm. Ten of the discs were evaluated colorimetrically using the CIE, L*, a*, b* system (control group). In addition, 50 discs, 3 mm in thickness and identical diameter, were fabricated using the following restorative materials (five different materials used on 10 specimens each): (1) high-precious gold alloy, (2) aluminum-oxide ceramic material, (3) titanium metal alloy, (4) yttrium-stabilized zirconium dioxide ceramic material, and (5) glass-ceramic material. The 50 veneered densely sintered alumina specimens were bonded to the 50 restorative specimens using an autopolymerizing luting composite. L*, a*, b* color coordinates were measured 10 times for each veneered densely sintered alumina specimen. Color differences were calculated using the equation DeltaE = [(DeltaL*)2 + (Deltaa*)2 + (Deltab*)2] 1/2. DeltaE values correspond to differences between the control group and each of the five materials groups. RESULTS: Mean color differences (DeltaE) and SDs for each group were as follows: DeltaE (1) = 1.42 +/- 0.5, DeltaE (2) = 1.53 +/- 0.5, DeltaE (3) = 1.55 +/- 0.4, DeltaE (4) = 1.95 +/- 0.5, DeltaE (5) = 1.23 +/- 0.3. All restorative materials induced changes to the densely sintered alumina color relative to the original color. One-way analysis of variance (ANOVA) tests showed statistically significant differences in DeltaE between the groups; however, the Student-Newman-Keuls test revealed that the only statistically significant difference was between groups 4 and 5. Color differences between the groups were not visually perceivable (DeltaE < 2). CLINICAL SIGNIFICANCE: Within the limits of this in vitro study, veneered densely sintered alumina adhesively fixed with dentine-like cement, successfully masks the shade of different metal or ceramic restorative materials.

Aluminum Oxide↗
PubMed2005

Compact monochromatic flash x-ray generator utilizing a disk-cathode molybdenum tube.

The high-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -50 to -70 kV by a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing gap switches in the surge generator with a trigger device. The x-ray tube is a demountable diode, and the turbo molecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean molybdenum Kalpha lines are produced using a 20 microm-thick zirconium filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. At a charging voltage of -70 kV, the instantaneous tube voltage and current were 120 kV and 1.0 kA, respectively. The x-ray pulse widths were approximately 70 ns, and the generator produced instantaneous number of Kalpha photons was approximately 3 x 10(7) photons/cm2 per pulse at 0.5 m from the source of 3.0 mm in diameter.

Animals↗
PubMed1974

Active insolubilized antibiotics based on cellulose-metal chelates.

Cellulose was converted into a more reactive form by chelation with the transition metals titanium(III), iron(III), tin(IV), vanadium(III), and zirconium(IV). The remaining unsubstituted ligands of the transition metal ions were found to be amenable to replacement by electron-donating groups of antibiotic molecules. Ampicillin, gentamicin, kanamycin, neomycin, paromomycin, polymyxin B, and streptomycin were used as antibacterial antibiotics, and amphotericin B and natamycin were used as antifungal antibiotics. Antibacterial activity of the products was tested against two gram-positive and two gram-negative bacteria, and antifungal activity was tested against four fungi. That the antibacterial antibiotics had complexed with the cellulose-metal chelates was demonstrated in that the product cellulose-metal-antibiotic chelates exhibited antibiotic activities whereas the metal chelates of cellulose themselves were inactive. Of 140 tests conducted, cellulose-metal-antibiotic chelates were active in 102 cases. Since the antibiotic derivatives were water insoluble and in fact retain some of the antibacterial activities of the parent compounds, the chelation method provides a facile way of rendering cellulose surfaces, etc., resistant to microbial attack over and above that degree of protection afforded by noncovalent adsorption of the antibiotic to cellulose itself. The underlying principles of the chelation reactions involved are discussed in detail.

Anti-Bacterial Agents↗
PubMed1972

A simple assay of intrinsic factor-vitamin B12 complex employing the binding intrinsic factor antibody.

The reaction between binding intrinsic factor antibody and intrinsic factor-vitamin B(12) complex has been studied. Initially in the zone of antibody excess, the relationship between the amount of antigen present and the amount of antigen-antibody complex adsorbed onto zirconium phosphate gel was linear. With increasing amounts of antigen, the curve departed from linearity and reached a plateau. The linear portion of the reaction forms the basis of a simple and reproducible assay for quantitating intrinsic factor to which vitamin B(12) has already been bound. The assay provides a method for studying the fate of intrinsic factor-vitamin B(12) complex during digestion and absorption. In two normal subjects given radioactive vitamin B(12) orally, aspiration of ileal contents showed that only 50 to 70% of the radioactivity was bound to intrinsic factor at that level.

Adsorption↗
PubMed1996

Non-fibrous inorganic particles in bronchoalveolar lavage fluid of pottery workers.

AIM: To study the actual exposure of pottery workers to silica particles, as their risk of silicosis is potentially high because of the presence of inhalable crystalline silica particles in the workplace. METHODS: Nine pottery workers underwent bronchoalveolar lavage. The recovered fluid was analysed for cytological and mineralogical content by analytical transmission electron microscopy. The data were compared with those obtained from a control group composed of seven patients with sarcoidosis and six patients with haemoptysis. RESULTS: Cytological results showed a similar profile in exposed workers and controls, whereas in patients with sarcoidosis a lymphocytic alveolitis was found. Microanalysis of the particulate identified the presence of silicates, CRSs, and metals. Pottery workers had higher numbers of total particles and CRSs, and had a higher silicate/metal ratio. In five workers, the presence of zirconium silicate was also detected. Patients with sarcoidosis had the lowest number of particles, and an inverted silicate/metal ratio. CONCLUSION: Microanalysis by transmission electron microscope can provide useful information to assess occupational exposure to dusts.

Adult↗
PubMed2026

A Phase I and Biodistribution Study of Ifabotuzumab, a Humanized Agonistic EphA3-Targeted Antibody, in Patients with Recurrent Glioblastoma.

PURPOSE: To conduct a phase I and biodistribution study of the EphA3 antibody ifabotuzumab and zirconium-89-labeled ifabotuzumab (89Zr-ifabotuzumab) in patients with glioblastoma (GBM). PATIENTS AND METHODS: This multisite study was conducted in adults with recurrent GBM whose tumors were measurable according to Response Assessment in Neuro-Oncology (RANO) criteria and whose Eastern Cooperative Oncology Group performance status was 0 to 1. Patients underwent a biodistribution study with PET scans with 89Zr-ifabotuzumab, followed by three infusions of ifabotuzumab at either 3.5 or 5.25 mg/kg before undergoing a second study with 89Zr-ifabotuzumab PET scans. Resected patient diagnostic tumor samples were collected for multiplex immunofluorescence and spatial transcriptomics analyses. RESULTS: Twelve patients were recruited, of which six were treated with 3.5 mg/kg and six with 5.25 mg/kg of ifabotuzumab. 89Zr-ifabotuzumab and associated PET scanning were well tolerated, as was ifabotuzumab. There were no objective responses, but one patient had prolonged stable disease. In addition, two patients showed changes in peritumor edema that were suggestive of modulation of tumor vasculature. 89Zr-ifabotuzumab scans showed highly specific tumor uptake in all patients concordant with disease sites on MRI and PET imaging, without evidence of nonspecific binding. Spatial transcriptomics and immunofluorescence analyses of the patient's archival tissue specimens showed that EphA3 was expressed in the tumor microenvironment in all patients and tumor cells with different transcriptional states. CONCLUSIONS: Targeting EphA3 with ifabotuzumab in patients with GBM is safe and attractive, showing chronologic stable expression across both tumor compartments (particularly in cells with a mesenchymal phenotype) and nontumor compartments (particularly the vascular compartment) with evidence of target modulation.

Humans↗
PubMedDate not supplied

Immunodiffusion and immunohistochemical investigations on the reactivity of oxide ceramic middle-ear implants.

Oxide ceramic materials (partial and total ossicular replacement prostheses) have been implants of preference for the reconstruction of the ossicular chain because of their excellent biocompatibility. The reaction on the surface of the implants takes place at three biodynamic levels according to the model of Stern's bilayer. We investigated the adsorption of proteins, which is determined by the cellular reaction and degradation to the surface using radial immunodiffusion and immunohistochemical methods. First, ceramic implants of aluminum oxide, hydroxyapatite, glass ceramic and zirconium oxide have individual actual (i.e. biological) surfaces. With a perthometer and the contact-free laser Focodyn method we determined each actual (i.e. biological) surface of the various ceramic implants mentioned above. Using radial immunodiffusion, the adsorption of albumin, glycoprotein, plasminogen, fibronectin, IgA, IgG and IgM shows characteristic rates of adsorption to the respective ceramic surfaces in correlating to the actual surface. A cross-check with fluorescent antibodies confirmed the protein adsorption. The individual surface adsorption of the proteins remains characteristic and is the basis for the recording of cellular reactions after implantation.

Adsorption↗
PubMed2004

Light transmission of posts and cores used for the anterior esthetic region.

Restoration of endodontically treated teeth is a routine procedure in everyday clinical practice. Placement of posts and cores is often required for replacement of the missing coronal aspect of teeth. Use of traditional post-and-core systems (gold and titanium) in conjunction with all-ceramic restorations results in poor esthetics because of the reflection and lack of light transmission. For a highly esthetic outcome, there is a need to use a material that transmits and refracts light in much the same manner as a natural tooth. The purpose of this study was to clinically evaluate the light transmission of a (1) ceramic post (Celay), (2) polyester post reinforced with zirconium fibers (Snowlight), and (3) zirconia post (Cosmopost), in comparison with a cast-metal post and core covered with opaque porcelain (control). The light transmission of these systems when used in conjunction with IPS Empress all-ceramic crowns was evaluated.

Aluminum Silicates↗
PubMed1998

Vascular cell attachment and procoagulant activity on metal alloys.

The attachment and growth of vascular smooth muscle cells on biomaterials used as components of devices implanted in the vascular space may influence the biocompatibility of such materials. The nature of the materials may affect the attachment and/or the activation of these cells' procoagulant responses. Therefore, the main objective of this study was to measure the strength of adhesion of these vascular cells to potential biomaterials (titanium, zirconium alloys, and stainless steel) by exposing them to a range of shear stresses (50-300 dyn cm(-2)) in a parallel plate flow chamber. The procoagulant responses of the cells were evaluated by measuring the tissue factor (TF) activity promoted by the different materials under flow conditions. The materials supported distinctly different levels of initial cell adhesion in static culture. However, the fraction of adherent cells did not decline significantly with incrementally increasing shear stress within the range tested. TF expression, as measured by factor Xa (FXa) production. was material-dependent. For example, cells cultured on Ti1313 exhibited more FXa production (13.2 nM 10(-5) cells) than Ti1313(DH) (8.5 nM 10(-5) cells) or stainless steel (2 nM 10(-5) cells). Thus, our studies indicate that the level of adhesion, strength of attachment and the expression of procoagulant activity of adherent vascular cells depend strongly on the nature of the underlying biomaterial.

Alloys↗
PubMed2005

Synthesis and thermal behaviour of nanostructured ZrO2 powders obtained under hydrothermal conditions.

Nanocrystalline zircone (ZrO2) powders were synthesized from zirconium oxyacetate aqueous solution treated up to 240 degrees C under autogeneous pressure. Depending on experimental conditions, colloidal particles of 26-150 nm are formed by aggregation of zirconia crystallites. The effect of some experimental conditions over the colloidal particle size or zirconia phase composition was studied. The powder sintering behaviour is also presented.

Colloids↗
PubMed2006

Patterning of ZrO2 precursor through a gas-generated self-assembly route.

We designed a gas-generated self-assembly route for patterning of ZrO2 precursor films from an aqueous peroxozirconium solution. Molecular oxygen generated during the decomposition of zirconium complex selectively aggregated on the hydrophobic surface of self-assembled monolayers, which was photo-modified to be a template. This gas layer prevented the solution from attaching to the substrate, so as the deposition of zirconia precursor occurred almost entirely on the hydrophilic sites. In comparison, only isolated islands of deposits were observed on hydrophobic sites, which may be attributed to contamination or adsorption of colloids during the preparation of samples. The resolution of pattern was well improved by using such a gas-generated process. In addition, this approach can be also extended to prepare other micropatterns.

Adsorption↗
PubMed1997

Radio-opaque agents in bone cement increase bone resorption.

A heavy infiltrate of foreign-body macrophages is commonly seen in the fibrous membrane which surrounds an aseptically loose cemented implant. This is in response to particles of polymethylmethacrylate (PMMA) bone cement and other biomaterials. We have previously shown that monocytes and macrophages responding to particles of bone cement are capable of differentiating into osteoclastic cells which resorb bone. To determine whether the radio-opaque additives barium sulphate (BaSO4) and zirconium dioxide (ZrO2) influence this process, particles of PMMA with and without these agents were added to mouse monocytes and cocultured with osteoblast-like cells on bone slices. Osteoclast differentiation, as shown by the presence of the osteoclast-associated enzyme tartrate-resistant acid phosphatase (TRAP) and lacunar bone resorption, was observed in all cocultures. The addition of PMMA alone to these cocultures caused no increase in TRAP expression or bone resorption relative to control cocultures. Adding PMMA particles containing BaSO4 or ZrO2, however, caused an increase in TRAP expression and a highly significant increase in bone resorption. Particles containing BaSO4 were associated with 50% more bone resorption than those containing ZrO2. Our results suggest that radio-opaque agents in bone cement may contribute to the bone resorption of aseptic loosening by enhancing macrophage-osteoclast differentiation, and that PMMA containing BaSO4 is likely to be associated with more osteolysis than that containing ZrO2.

Acid Phosphatase↗
PubMed2001

The effects of particulate bone cements at the bone-implant interface.

We used a rat model in vivo to study the effects of particulate bone cements at the bone-implant interface. A ceramic pin was implanted into the tibiae of 48 rats. Three types of particle of clinically relevant size were produced from one bone-cement base without radio-opacifier, with zirconium dioxide (ZrO2) and with barium sulphate (BaSO4). The rats were randomly assigned to four groups to receive one of the three bone cements or normal saline with 2% v/v Sprague-Dawley serum as the control. A total of 10(9) particles was injected into the knee at 8, 10 and 12 weeks after the original surgery. The animals were killed at 14 weeks and the tibiae processed for histomorphometry. The area of fibrous tissue and the gap between the implant and bone were measured using image analysis. All three types of particle were associated with a larger area of bone resorption than the control. Only in the case of the BaSO4-containing cement did this reach statistical significance (p = 0.01). Particles of bone cement appear to promote osteolysis at the bone-implant interface and this effect is most marked when BaSO4 is used as the radiopaque agent.

Animals↗
PubMed1996

Evaluating the antagonistic wear of restorative materials when placed against human enamel.

Several clinical and laboratory studies have reported data on the nature of tooth wear against restorative materials (that is, amalgam, gold, glass ceramic and various composite resin systems). Several antagonistic substrates are known to cause various in vitro wear rates when placed in opposition to enamel. In this study, the authors evaluated 10 commercially available posterior composite resin systems and a gold alloy control. The findings showed that posterior composite resins containing zirconium silicate or quartz fillers caused greater antagonistic enamel wear than did microfilled or barium silicate-filled composite resins.

Analysis of Variance↗
PubMed2006

In vitro evaluation of the retention of zirconia-based ceramic posts luted with glass ionomer and resin cements.

The retention of zirconia-based ceramic posts (CosmoPost system) luted with glass ionomer and resin cements was evaluated. Thirty-two extracted, caries-free, unrestored teeth were selected and stored in chlorhexidine and water solution. The teeth were endodontically treated and randomly assigned to two groups (n=16). Each tooth was decoronated and prepared to a depth of 10.0 mm from root surface to receive a 1.4 mm diameter zirconium dioxide post. Each group had posts cemented with either glass ionomer cement (Fuji I) or resin cement (Variolink II). The post/teeth specimens were embedded in resin blocks and subjected to tensile testing. The tensile force required to dislodge the cemented posts in a tensile testing machine was recorded. The mean stress values of both groups were analyzed for statistical differences using ANOVA and Student's t-test. Significance level was set at 5%. Mean peak forces at failure (N) and standard deviation for the tested cements were the following: Fuji I = 121.8 (+/-17.4) and Variolink II = 228.1 (+/-36.8). Posts luted with the resin cement presented statistically significant higher tensile bond strength than those retained with glass ionomer (p<0.05). It may be concluded that zirconia posts cemented with resin-based cement (Variolink II) failed at statistically significant higher values compared to those cemented with glass ionomer cement (Fuji I). Regardless of the cement type, the posts failed adhesively at the cement/post interface when subjected to a tensile force.

Acid Etching, Dental↗
PubMed2000

Metal-oxide nanoparticles for the reinforcement of dental restorative resins.

Metal oxide nanoparticles were synthesized from tantalum ethoxide and zirconium isopropoxide and subsequently surface grafted with vinyl silane and silyl methacrylate coupling agents. The nanoparticles were then dispersed into a commercial dental resin, and the composite was photocured into rigid three-point bend and fracture toughness specimens. The optically transparent/translucent cured composites demonstrated strength, toughness, and elastic modulus inferior to the unfilled material. Therefore, modifications in surface functionalization are being made to improve coupling and reduce interparticle associations.

Biocompatible Materials↗
PubMed2004

Different titanium surface treatment influences human mandibular osteoblast response.

BACKGROUND: Six titanium disks with six different surface treatments were examined: SS: smooth (polished) surface; TPS: plasma spray; C100: sand blasting by aluminum oxide (Al2O3) diameter 100 microm and acid etching; C150: sand blasting by Al2O3 diameter 150 microm and acid etching; B60: sand blasting by zirconium oxide (ZrO2) diameter 60 microm and acid etching; and B120: sand blasting by ZrO2 diameter 120 microm and acid etching. METHODS: The surface characteristics were determined by scanning electron microscopy (SEM) observation and a roughness tester. Raman spectroscopy was used to determine the presence of residual substances on the samples. Cells were seeded onto the disk and after 24 hours, 6 days, and 12 days were observed under SEM and growth curves generated with a cell counter. Some samples were used to determine alkaline phosphatase activity (ALP), using a colorimetric assay. RESULTS: SEM observation revealed drastic differences in surface microtopography, with a higher cell density on sand-blasted and acid-etched (SLA) samples than SS and TPS, and more regularly aligned cells on B60 and B120 surfaces than on the others. The growth curves showed a greater adhesion of cells on the etched/blasted surfaces compared to the SS and TPS surfaces. The number of cells increased on all the SLA samples, especially B60, throughout the experiment. At the same time, there was considerable ALP activity on the B60 sample, while it remained at extremely low levels on SS and TPS surfaces. Raman analyses revealed Al2O3 debris on C100 and C150, partly explaining the poorer performances of these two surface treatments, since this substance was shown to be toxic for cultured osteoblasts. CONCLUSIONS: Surface treatments influence the growth and the metabolic activity of cultured osteoblasts, and B60 seems to be the most favorable surface inducing a more pronounced proliferation of cells together with a high differentiation degree.

Acid Etching, Dental↗