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PubMed2006

Retention of zirconium oxide ceramic crowns with three types of cement.

STATEMENT OF PROBLEM: Information about the retentive strength of luting agents for zirconium oxide-based crowns is limited. It is unknown if this type of high-strength ceramic restoration requires adhesive cementation to enhance retention. PURPOSE: The purpose of this in vitro study was to determine the ability of selected luting agents to retain a representative zirconium oxide ceramic crown under clinically simulated conditions. MATERIAL AND METHODS: Recently extracted human molars were prepared with a flat occlusal surface, 20-degree taper, and approximately 4-mm axial length. The axial and occlusal surface areas were determined, and specimens were distributed equally by total surface area into 3 cementation groups (n=12). Zirconium oxide ceramic copings (Procera AllZirkon) with an occlusal bar to facilitate removal were fabricated using computer-aided design/computer-assisted manufacturing (CAD/CAM) technology. All copings were airborne-particle abraded with 50-mum Al(2)O(3) and then cleaned in an ultrasonic bath with isopropyl alcohol. Provisional cement was removed from the prepared teeth, followed by a pumice prophy. After trial insertion, the copings were cleaned with phosphoric acid, rinsed, dried, and dehydrated with isopropyl alcohol. They were then cemented with a seating force of 10 kg per tooth, using either a composite resin cement with adhesive agent (Panavia F 2.0 and ED Primer A & B [PAN]), a resin-modified glass ionomer cement (Rely X Luting [RXL]), or a self-adhesive modified composite resin (Rely X Unicem [RXU]). The cemented copings were thermal cycled at 5 degrees C and 55 degrees C for 5000 cycles with a 15 second dwell time, and then removed along the path of insertion using a universal testing machine at 0.5 mm/min. The removal force was recorded, and the stress of dislodgement was calculated using the surface area of each preparation. A 1-way analysis of variance was used to analyze the data (alpha=.05). The nature of failure was also recorded. RESULTS: Mean dislodgement stresses were 5.1, 6.1, and 5.0 MPa for PAN, RXL, and RXU, respectively. The 1-way analysis of variance revealed no differences in mean crown removal stress among the 3 cementation groups. The predominant mode of failure was cement remaining principally on the zirconium oxide copings in 46% of the specimens, followed by cement found on the tooth in 25.7% of the specimens. CONCLUSIONS: Within the limitations of this study, the 3 luting agents, with mean removal stresses ranging from 5.0 to 6.1 MPa were not significantly different. The use of a composite resin cement with a bonding agent did not yield higher coping retention compared to the other 2 cements tested.

Adhesiveness↗
PubMed2001

Application of zirconium-modified silica gel as a stationary phase in the ion-exclusion chromatography of carboxylic acids. I. Separation of benzenecarboxylic acids with tartaric acid as eluent and with UV-photometric detection.

The application of zirconium-modified silica gels (Zr-Silicas) as stationary phases for ion-exclusion chromatography with UV-photometric detection (IEC-PD) for mono-, di-, tri- and tetrabenzenecarboxylic acids (pyromellitic, trimellitic, hemimellitic, o-phthalic, salicylic and benzoic acids) and phenol was carried out using tartaric acid as the eluent. Zr-Silicas were prepared by the reaction of the silanol group on the surface of silica gel with zirconium tetrabutoxide [Zr(OCH2CH2CH2CH3)4] in ethanol solution. The effect of the amount of zirconium adsorbed on silica gel on chromatographic behavior of these benzenecarboxylic acids and phenol was investigated. As a result, Zr-Silica adsorbed on 20 mg zirconium g(-1) silica gel was the most suitable stationary phase in the IEC-PD for the simultaneous separation of these benzenecarboxylic acids and phenol. Excellent simultaneous separation and highly sensitive UV detection at 254 nm for these benzenecarboxylic acids and phenol were achieved in 20 min by the IEC-PD using the Zr-Silica column (250x4.6 mm I.D.) and a 10 mM tartaric acid at pH 2.5 as eluent.

Adsorption↗
PubMed2003

A re-evaluation of the biokinetics of zirconium in humans.

There is much interest in understanding the biokinetics of zirconium in humans due to the potential radiological risk represented by the radionuclide 95Zr and by its daughter 95Nb. Despite the significance of zirconium, few data are available on the actual biokinetics of zirconium in humans. Accordingly the biokinetic model currently recommended by ICRP for this element is based mainly on data from animal experiments. In this study, the use of the stable isotopes 90Zr and 96Zr as tracers has enabled the conduct of 6 biokinetic investigations in 3 healthy volunteers. These studies have provided new valuable information about intestinal absorption and kinetics in blood plasma of zirconium and have been used for the set-up of a more realistic compartmental model with possible applications for dosimetric purposes.

Adult↗
PubMed2006

Remarkably stable chiral zirconium complexes for asymmetric Mannich-type reactions.

Isolable, air-stable, storable, and highly selective chiral zirconium catalysts for asymmetric Mannich-type reactions have been developed. The reactions of imines with silicon enolates proceeded smoothly using 1-10 mol % of the powdered zirconium catalyst to afford the corresponding adducts in high yields with high stereoselectivities. The catalyst could be recovered and reused without significant loss of activity. On the other hand, zirconium single crystals for X-ray analysis were obtained, and the crystals also showed high performance in the asymmetric Mannich-type reactions. Although NMR analyses of these zirconium catalysts showed different structures in dichloromethane, the formation of the same key intermediate from the different catalysts was indicated.

Magnetic Resonance Spectroscopy↗
PubMed2004

Catalytic activity of myoglobin immobilized on zirconium phosphonates.

The adsorption and catalytic activity of myoglobin (Mb) on zirconium phosphonates (a-zirconium benzenephosphonate (alpha-ZrBP), a-zirconium carboxyethanephosphonate (alpha-ZrCEP), and a novel layered zirconium fluoride aminooctyl-N,N-bis(methylphosphonate) (ZrC8)) were investigated. The maximum adsorption was reached after 16 h of contact and was greater on hydrophobic supports such as alpha-ZrBP and ZrC8 compared to hydrophilic supports such as alpha-ZrCEP. The equilibrium adsorption isotherms fitted the Langmuir equation, suggesting the presence of a monolayer of protein molecules on the support surfaces. The catalytic activities of free Mb and of the obtained biocomposites were studied in terms of the oxidation of two aromatic substrates, o-phenylenediamine and 2-methoxyphenol (guaiacol), by hydrogen peroxide. The oxidation catalyzed by immobilized myoglobin followed the Michaelis-Menten kinetics, similar to oxidation by free Mb. The kinetic parameters, kcat and KM, were significantly affected by the adsorption process. Mb/alpha-ZrCEP was the most efficient biocatalyst obtained, probably because of the hydrophilic nature of the support. The effect of immobilization on the stability of Mb toward inactivation by hydrogen peroxide was also investigated, and an increased resistance was found. The biocomposites obtained can be stored at 4 degrees C for months without a significant loss of catalytic activity.

Adsorption↗
PubMed1978

Bronchopulmonary cellular response to aluminum and zirconium salts.

The bronchopulmonary cellular immunological response to repeated intratracheal inoculation of aluminum chlorhydrate, sodium zirconium lactate, and zirconium aluminum glycine was examined in rabbits. Results of a dose-response experiment using 0.1, 1.0, and 10.0-mg intratracheal inoculations of each metallic salt demonstrated significant bronchopulmonary histopathology in the 10.0-mg dose-response groups only. Acute lesions were histologically characterized by an inflammatory response centered around respiratory bronchioles. Although epithelioid cell formation was evident in 10.0 mg of aluminum salt (aluminum chlorhydrate and zirconium aluminum glycine) -injected animals, no well-defined granulomas characterized by an orderly arrangement of epithelioid cells, lymphocytes, and giant cells were evident in any of the experimental groups employed. All three metallic salts induced "activated" bronchopulmonary macrophages as determined by an in vitro phagocytic assay. This activation was likely nonimmunological since no measurable differences were observed in metallic salt-induced delayed skin reactivity or migration inhibition factor production between inoculated and uninoculated rabbits. The above observations suggest that aluminum and zirconium salts administered in comparatively high dosage via the respiratory tract route can induce respiratory bronchiolitis and activation of alveolar macrophages in the absence of demonstrable delayed hypersensitivity.

Aluminum↗
PubMed1987

IgM antibody production in mice intraperitoneally injected with zirconium oxychloride.

The effect of zirconium (Zr) on the humoral immune response was studied by measuring the level of IgM-plaque forming cells (IgM-PFC) against sheep red blood cells (SRBC) in the spleen of C57 BL mice intraperitoneally injected with zirconium oxychloride. Two experiments, a single injection of zirconium oxychloride of 1/5, 1/10, 1/50, and 1/100 of the LD50 for intraperitoneal injection and continuous injection of 1/20, 1/40, and 1/80 of the LD50 every other day for two or four weeks in mice, were carried out. In the case of a single injection zirconium oxychloride was intraperitoneally injected on days -1, 0, +1, +2, and +3 in relation to SRBC immunisation. The following conclusions may be drawn from this study: (1) Zr was shown to have an adjuvant like activity in relation to the humoral immune response, at least to IgM antibody production; (2) this effect was recognised not only with a single injection with Zr but also after continuous injection; (3) a single injection of Zr was more effective when the mice were treated with Zr 24 hours before or after SRBC immunisation; and (4) with regard to an injected dose of Zr, it was shown that a lower dose (1/50, 1/100 of the LD50 for a single injection and 1/40, 1/80 of the LD50 for continuous injection) led to a more enhanced level of IgM-PFC than a higher dose (1/5, 1/10 of the LD50 for a single injection, and 1/20 of the LD50 for continuous injection).

Animals↗
PubMed2005

Total hip replacement with a zirconium oxide ceramic femoral head: a randomised roentgen stereophotogrammetric study.

We investigated the wear characteristics and clinical performance of four different total hip joint articulations in 114 patients. Wear and migration was measured by roentgenstereophotogrammetric analysis at five years or at the last follow-up. The mean annual wear was 0.11 mm for a stainless steel/Enduron articulation, 0.34 mm for stainless steel/Hylamer cup, 0.17 mm for zirconium oxide ceramic/Enduron and 0.40 mm for zirconium oxide ceramic/Hylamer. The difference between the groups was significant (p < 0.008) except for stainless steel/Hylamer vs zirconium oxide ceramic/Hylamer (p = 0.26). At present, 12 patients have undergone a revision procedure, four at five years and eight thereafter. No patient who received a stainless steel/Enduron articulation at their primary replacement required revision. Conflicting results have been reported about the performance of the zirconium oxide ceramic femoral head, but our findings suggest that it should not be used with a polymethylmethacrylate acetabular component. Hylamer has already been withdrawn from the market.

Aged↗
PubMed1978

Determination of zirconium in natural water by spectrophotometry following the concentration step with yield tracer.

Zirconium in natural water samples was determined spectrophotometrically after concentration using95Zr as a yield tracer. Acidified sample (1l) with a known amount of 95Zr was evaporated to dryness, treated with hydrofluoric and nitric acids, and then with nitric and perchloric acids, and evaporated nearly to dryness. The residue was taken up with 2 M perchloric acid and zirconium in the solution was extracted with 0.1 M thenoyltrifluoroacetone (TTA) in benzene. The TTA complex solution was converted to hydrochloric acid solution. After the recovery yield was estimated by measuring the radioactivity of 95Zr in the final solution, zirconium was then determined by spectrophotometry with Arsenazo III. Zirconium contents in lake and hot and cold spring samples from Nikko and Shiobara districts were found to be 0.29-2.8 microgram/l by this method.

Fresh Water↗
PubMed1999

Intermittent loading of teeth restored using quartz fiber, carbon-quartz fiber, and zirconium dioxide ceramic root canal posts.

PURPOSE: The purpose of the investigation was to compare the performances of teeth restored with quartz fiber, carbon-quartz fiber, and zirconium-dioxide posts covered with all-ceramic crowns when subjected to a cyclic loading test performed in a wet environment. MATERIALS AND METHODS: Forty single-rooted human lower premolars having similar dimensions were endodontically treated and mounted in acrylic resin blocks with a simulated periodontal ligament. The teeth were divided into three experimental groups and one control group. Post holes 8 mm long were prepared in the roots of the experimental groups in which quartz fiber, carbon-quartz fiber, and zirconium dioxide posts were cemented. In the control group, no posts were used. The crown buildup was made with composite resin. The teeth were covered with all-ceramic crowns and intermittently loaded at an angle of 45 degrees to the long axis of the tooth at a frequency of two loads per second. RESULTS: Only one failure (root fracture + post fracture) was observed in each of the fiber post groups, while in the zirconium dioxide post group, six failures were observed (one crown fracture and 5 root fractures + post fractures). The Kaplan-Meier analysis of the three experimental groups showed that the survival rate of zirconium dioxide posts was significantly lower than that of both types of fiber post. All the experimental groups showed a survival rate higher than that of the control group. CONCLUSION: Fiber posts reduced to a minimum the risk of root fractures of teeth restored with composite cores and Empress crowns under the present experimental conditions (intermittent loading in a wet environment).

Aluminum Silicates↗
PubMed1965

Zirconium granuloma following treatment of rhus dermatitis.

Zirconium granuloma of the skin, initially seen following the use of zirconium deodorants, continues to occur secondary to the treatment of plant dermatitis with compounds containing zirconium. In our patient the reaction appeared eight weeks after initial use of the agent and has persisted for 18 months without therapy. Intradermal injection of minute amounts of a soluble zirconium compound resulted in production of a lesion that was identical clinically and histologically with the primary lesion at the end of four weeks. Although this disorder involves the skin primarily, the slight elevation in gamma-globulin level observed may be a reflection of its systemic pathogenesis.

Adolescent↗
PubMed2004

Zirconate coupling agent for bonding resin luting cement to pure zirconium.

PURPOSE: To evaluate the shear bond strengths of two dual-cured resin luting cements to pure zirconium and the effect of zirconate coupling agent on the bond strength. METHODS: The two different-shaped pure zirconium specimens (99.9%) were untreated or treated with one of the four primers including zirconate coupler and then cemented together with one of the two dual-cured resin luting cements. Half of the specimens were stored in water at 37 degrees C for 24 hours and the other half thermocycled 20,000 times before shear bond strength testing. RESULTS: Regardless of the resin luting cement and thermocycling, specimens treated with the mixture of zirconate coupler and resin bonding agent showed the highest shear bond strength among the five treatments. Surface treatment with the mixture of zirconate coupler and resin bonding agent showed significantly greater shear bond strength compared with other treatments at 20,000 thermocycles. The application by the mixture of zirconate coupler and resin bonding agent on the pure zirconium metal surface appears to be effective for bonding between zirconium and dual-cured resin luting cements.

Aluminum Silicates↗
PubMedDate not supplied

Clinical success of zirconium oxide posts with resin composite or glass-ceramic cores in endodontically treated teeth: a 4-year retrospective study.

PURPOSE: This study retrospectively evaluated zirconium oxide posts with either direct resin composite cores or indirect glass-ceramic cores after several years of clinical service. MATERIALS AND METHODS: One hundred forty-five endodontically treated teeth in 88 patients were restored with zirconium oxide posts; 87 teeth were restored with direct composite cores, and 58 were restored with Empress cores prior to crowning. Seventy-nine posts with direct composite cores in 52 patients and 34 posts with glass-ceramic cores in 19 patients were reevaluated clinically and radiographically after a mean clinical service of 57.7 months and 46.3 months, respectively. RESULTS: Periodontal probing depths remained on a healthy clinical level, and esthetics were judged excellent for the majority of teeth in both groups. In the group with direct composite cores, no failures were observed in the 79 posts that were reevaluated. In the group with indirect glass-ceramic cores, three failures were observed after 42, 43, and 55 months of clinical service. All failures were due to loss of retention. In a best-case scenario posts that could not be reevaluated were considered successful, and in a worst-case scenario they were considered failures; respective success rates were 100% and 91% in the direct group and 95% and 53% in the indirect group. CONCLUSION: The observed clinical success of zirconium oxide posts with direct composite cores suggests that this method of post-and-core reconstruction is clinically promising. Zirconium oxide posts with indirect glass-ceramic cores displayed a significantly higher failure rate and a high dropout rate that precludes valid conclusions.

Adolescent↗
PubMedDate not supplied

Precision of a CAD/CAM technique for the production of zirconium dioxide copings.

PURPOSE: The precision of a computer-aided design/manufacturing (CAD/CAM) system to manufacture zirconium dioxide copings with a predetermined internal space was investigated. MATERIALS AND METHODS: Two master models were produced in acrylic resin. One was directly scanned by the Decim Reader. The Decim Producer then manufactured 10 copings from prefabricated zirconium dioxide blocks. Five copings were prepared, aiming for an internal space to the master of 45 microm. The other five copings were prepared for an internal space of 90 microm. The second test model was used to try in the copings produced. The obtained internal space of the ceramic copings was evaluated by separate measurements of the master models and inner surfaces of the copings. The master models were measured at predetermined points with an optical instrument. The zirconium dioxide copings were measured with a contact instrument at the corresponding sites measured in the masters. RESULTS: The first group of copings had a mean internal space to the scanned master of 41 microm and of 53 microm to the try-in master. In general, the internal space along the axial walls of the masters was smaller than that along the occlusal walls. The second group had a mean internal space of 82 microm to the scanned master and of 90 microm to the try-in master. CONCLUSION: The aimed-for internal space of the copings was achieved by the manufacturer. The CAD/CAM technique tested provided high precision in the manufacture of zirconium dioxide copings.

Computer-Aided Design↗
PubMed1982

In vitro adsorption of oxalic acid and glyoxylic acid onto activated charcoal, resins and hydrous zirconium oxide.

Patients suffering from primary hyperoxaluria show elevated plasma concentrations of oxalic acid and glyoxylic acid. The in vitro adsorption of these compounds into activated charcoal, a series of neutral and ion exchange resins and onto hydrous zirconium oxide has been investigated. Hydrous zirconium oxide was the most effective sorbent studied for the removal of both oxalic acid and glyoxylic acid. In batch experiments, the zirconium oxide was capable of binding 5.5 mu mol oxalic acid and 8 mu mol glyoxylic acid per gram sorbent using 0.5 gram sorbent and 50 ml of solutions with initial concentrations of 100 mu mol . L-1 and an ionic composition resembling that of plasma. Recirculation of 2 L of the same solutions through 12 gram of a mixture of hydrous zirconium oxide and alumina for 6 hours at a flow rate of 12 ml . min-1, resulted in a final concentration of 70 mu mol . L-1 of oxalic acid and 50 mu mol . L-/ of glyoxylic acid.

Adsorption↗
PubMed2002

Single crystal structure determination of a new zirconium N-ethylpyridinium phosphonate: Zr(O(3)PCH(2)CH(2)NC(5)H(5))(F(-))(3).

We describe the structure of a new zirconium N-ethylpyridinium phosphonate, Zr(O(3)PCH(2)CH(2)NC(5)H(5))(F(-))(3), that has been determined by single-crystal X-ray analysis (monoclinic, P2(1)/c (No. 14), a = 12.3634(12) A, b = 9.3090(17) A, c = 9.8077(13) A, beta = 112.819(8) degrees, V = 1040.4(3) A(3), Z = 4). This structure is unlike any other reported zirconium phosphonate. Octahedral coordination about zirconium is completed by three oxygen atoms of three different phosphonate groups and three fluoride ligands. The structure is composed of corrugated infinite layers of these Zr octahedra that corner share their three oxygen atoms with the phosphonate tetrahedra. The appended cationic pyridinium groups lie between the inorganic sheets and are charge-balanced by the [Zr(O(3)P-)(3)F(3)](-) octahedra. This structure represents a new example of the structure-directing influence of cationic organic ligands on the zirconium phosphonate framework.

Journal Article↗
PubMed2003

Structural motifs in (t-butoxy) zirconium phosphinates, arsinates, and phosphates.

Reaction of zirconium tetrakis(tert-butoxide) (1) with dicylohexylphosphinic acid in toluene leads to the dinuclear compound [Zr(mu,mu'-O(2)P(cycl-C(6)H(11))(2))(O-t-Bu)(3)](2) (2) in which the zirconium is pentacoordinated. An analogous reaction using diphenylphosphinic acid in tetrahydrofuran also leads to a dinuclear complex [Zr(mu,mu'-O(2)PPh(2))(THF)((O-t-Bu)(3)](2).C(6)H(5)CH(3) (3.C(6)H(5)CH(3)), in which zirconium is hexacoordinated. A novel exchange of tert-butoxy and phenoxy groups occurs when 1 is treated with diphenyl phosphate [(PhO)(2)PO(2)H] leading to the isolation of the exchange product [Zr(mu,mu'-O(2)P(O-t-Bu)(OPh))(mu-OPh)(O-t-Bu)(2)](2) (4). In contrast to the above, trinuclear zirconium compounds Zr(3(mu,mu'-O(2)AsMe(2))(2)(mu2,mu'-O(2)AsMe(2))(O-t-Bu)(7)(mu-O-t-Bu)(2) (5) and Zr(3(mu,mu'-O(2)P(O-t-Bu)(2))(5)(O-t-Bu)(7).(1)/(2)C(6)H(5)CH(3) (6.(1)/(2)C(6)H(5)CH(3)) have been isolated from the reaction of 1 with cacodylic acid and di-tert-butyl phosphate, respectively. The X-ray structures of 2, 3, 5, and 6 have been determined; although the X-ray structural analysis of 4 could not be satisfactorily finished, it reveals the disposition of the substituents. The solution state NMR data suggest that these compounds undergo structural changes in solution. Possible relationships among the various structures are discussed.

Journal Article↗
PubMed2005

Zirconium arene-phosphonates: chemical and structural characterization of 2-naphthyl- and 2-anthracenylphosphonate systems.

Several new zirconium phosphonates incorporating naphthalene and anthracene ring systems and having the general formula Zr(O3PR)1(O3PR')1 [R and R' = -C10H7, -C14H9, -OC4H9, and -OC2H5] have been synthesized. These compounds were chemically characterized using thermal gravimetric analysis (percentage of organic content), infrared spectroscopy (presence of the desired organic functional groups), and solid-state 31P NMR (phosphorus environments), while the structural parameters were determined using X-ray powder diffraction (interlayer d spacings). The d spacings of the zirconium bis(phosphonates) correlate well with a simple predictive model based on the effective length of the organic functional group. The zirconium mixed phosphonates examined are single-phase structures with random mixtures of the organic moieties within the interlayer and possess d spacings that are between those of the two parent zirconium bis(phosphonates).

Journal Article↗