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At least 1,063 records · Page 59Linked to original sources
PubMed1999

Compressibility of two polyvinyl siloxane interocclusal record materials and its effect on mounted cast relationships.

STATEMENT OF PROBLEM: Addition silicones (polyvinyl siloxanes) are universally accepted as accurate and stable impression materials. They have also gained popularity as interocclusal record materials. However, it has not been defined if it is possible to work with polyvinyl siloxanes without changing the recorded maxillomandibular relations. PURPOSE: This study examined the compressibility of 2 addition silicones as interocclusal record materials, analyzing the changes of maxillomandibular relations at the condyle region when different compressive forces are used to stabilize articulated casts. MATERIAL AND METHODS: Sixteen interocclusal records, obtained from the same patient (8 of each polyvinyl siloxane, Blu-Mousse, Fast Set), were interposed between the patient casts in a new measuring system obtaining 48 curves of load versus maxillomandibular positional changes in 3 axes (x, y, z). These curves were compared with curves obtained with the casts in maximum intercuspation without interocclusal records (reference curves). Analysis of variance was used to compare maxillomandibular positional changes among the 3 groups (n = 48 each): Blu-Mousse, Fast Set, and control group or maximum intercuspation without interocclusal record. RESULTS: There was no significant change in maxillomandibular relations when forces up to 1 kgf were applied to stabilize the casts related by means of Blu-Mousse and Fast Set addition silicone interocclusal records. CONCLUSION: It is possible to use these polyvinyl siloxanes as interocclusal record materials without changing the recorded maxillomandibular relations.

Analysis of Variance↗
PubMed1999

Effect of sandblasting and silicoating on bond strength of polymer-glass composite to cast titanium.

STATEMENT OF PROBLEM: There is little information regarding the mechanical and chemical retention of polymer-glass composite to cast titanium. PURPOSE: This study examined whether sandblasting in conjunction with silicoating improves the bond strength of the polymer-glass composite to cast titanium. MATERIALS AND METHODS: Disk patterns (10 mm in diameter, 2.5 mm thick) were cast with commercially pure titanium (CP Ti) and Type IV gold alloy. Three pretreatments were applied: 50 microm Al(2)O(3) sandblasting (50 SB), 250 microm Al(2)O(3) sandblasting (250 SB), and 600-grit SiC paper polishing (600 SiC). After surface preparation, the Siloc system (silicoating) was applied on the disks. The 50 SB specimens without Siloc system were also prepared as controls. Then sticky tape with a circular hole (4.76 mm diameter) was placed onto the disk to define the bonding area. Artglass (polymer-glass) opaque, dentin, and enamel composites were applied using Teflon matrices and then light-polymerized. Shear bond strength (n = 8) was determined at a crosshead speed of 5 mm/min. Results were analyzed statistically with 2-way ANOVA and the Tukey-Kramer test (alpha=.05). RESULTS: The Siloc system significantly (P <.05) improved the mean shear bond strength of Artglass to both metals in the 50 SB specimens. Statistical differences (P <.05) in shear bond strength were found among surface treatments for the silicoated CP Ti specimens, in which 250 SB specimens yielded the greatest bond strength. The Type IV specimens treated with Siloc system showed no significant differences in shear bond strength between the 50 SB and the 250 SB specimens. CONCLUSION: Sandblasting with coarser alumina particles in conjunction with silicoating significantly enhanced bond strength of polymer-glass composite to cast titanium.

Analysis of Variance↗
PubMed1999

Procedure to prevent cast breakage during separation from elastomeric impressions.

This article describes a quick and simple procedure for removing dental stone casts from elastomeric impressions. Frequently, dental stone casts break at the time of separation because of the rigidity of the impression material. The materials used in this technique are inexpensive and easy to use. When this method is properly used, it simplifies the removal of the cast from the impression, decreasing the chance of fracture of the cast.

Dental Impression Materials↗
PubMed1997

Pantaloon spica cast: an effective method for postoperative immobilization after free graft hypospadias repair.

PURPOSE: We used a postoperative dressing of silicone foam in conjunction with a pantaloon spica cast to optimize the chances for successful graft take in hypospadias repairs with grafts. We compared the results to those of inpatient bed restriction. MATERIALS AND METHODS: A total of 15 patients underwent graft urethroplasty, and application of a penile silicone foam dressing and fiberglass pantaloon spica cast. Patients were discharged home the following morning. RESULTS: Two fistulas developed. Results are no different from those of our previously reported cases which required 6 or 7 days of hospitalization. CONCLUSIONS: We believe that the pantaloon spica cast provides necessary immobilization for facilitating imbibition and inosculation, which are required for graft survival. Also, the spica cast allows early discharge home, obviating the need for prolonged hospitalization and bed rest.

Bandages↗
PubMed1984

Identification of fungal casts in a patient with renal candidiasis.

Since the treatment of fungal infections with amphotericin B may result in significant nephrotoxicity, better methods for discriminating between life-threatening and more benign fungal infections are needed. Recently numerous fungal casts were identified in the urine of a patient who had undergone renal allograft transplantation. The recognition of fungal casts permitted an unequivocal diagnosis of systemic fungal infection. Successive examinations of the patient's urinary sediment provided an excellent monitor of the response to treatment. The cytologic features of fungal casts are described. Since systemic fungal infections often involve the kidney, screening for fungal casts may have significant clinical applicability.

Adult↗
PubMed1997

Transmission electron microscopic investigation of high-palladium dental casting alloys.

OBJECTIVE: The purpose of this study was to use transmission electron microscopy to examine four representative high-palladium alloys and gain insight into possible strengthening mechanisms. METHODS: Castings of two Pd-Cu-Ga alloys and two Pd-Ga alloys were thinned by jet polishing and ion milling, followed by plasma cleaning, to yield foil specimens. Multiple specimens were prepared for each alloy. Bright-field images, dark-field images and selected-area electron diffraction patterns for the alloys in the as-cast condition, after simulated porcelain-firing heat treatment, and after annealing at 980 degrees C were analyzed by standard transmission electron microscope (TEM) techniques. The overall compositions of the ultrastructures for the specimen foils were determined by conventional standardless energy-dispersive spectroscopic analyses with the TEM, and mean values of the elemental compositions were compared to the nominal alloy compositions provided by the manufacturers. RESULTS: There was generally good agreement (differences less than 2 wt%) between the overall ultrastructure composition and each nominal alloy composition, except for Protocol from which in may have been lost during casting or formed intermetallic compounds that were not detected by TEM. The same fine-scale tweed structure within parallel bands of approximately 100-200 nm width was observed for all four alloys in the as-cast condition and after simulated porcelain-firing heat treatment. The persistence of the ultrastructure in the specimens of the two Pd-Cu-Ga alloys annealed at 980 degrees C and quenched in ice water indicated very rapid formation from the palladium solid solution. The presence of ¿100¿ and ¿110¿ forbidden reflections for the <001> zone suggested that the tweed structure is ordered, although further research is necessary to establish this conclusion. SIGNIFICANCE: The presence of a similar tweed structure in both the Pd-Cu-Ga alloys and the Pd-Ga alloys of substantially lower hardness shows that some other strengthening mechanism accounts for the high hardness and strength generally observed for Pd-Cu-Ga alloys.

Copper↗
PubMed2002

Mutation analysis of the calpastatin gene (CAST) in patients with Alzheimer's disease.

The calpains, a family of calcium-dependent cysteine proteinases, and calpastatin, their endogenous inhibitor protein, are involved in the proteolysis of amyloid precursor protein, which is thought to be abnormal in patients with Alzheimer's disease (AD). Specific inhibitors of calpains attenuate amyloid beta peptide-induced neuronal death. We hypothesized that some AD patients have functionally deficient mutation(s) of the CAST gene encoding calpastatin, and we screened 40 Japanese patients with AD for mutations in the coding region of CAST. Nine polymorphisms, -82A/G, IVS7-96A/G, 669A/G, 1223C/G (Ser408Cys), IVS20-10C/T, IVS21-65G/A, IVS22+31T/C, IVS24+38Ins/DelA, and IVS25-32A/G, were identified. The 669A allele causes skipping of exon 11, leading to the loss of 13 residues. Comparisons between 101 patients and 90 controls revealed no significant association between CAST polymorphisms and risk for AD, indicating that genomic variations of CAST are not likely to be substantially involved in the etiology of AD.

Aged↗
PubMed1986

Treatment of nonunited scaphoid fractures by pulsed electromagnetic field and cast.

Thirty-five of 44 nonunited scaphoid fractures that were at least 6 months old healed in a mean time of 4.3 months during pulsed electromagnetic field (PEMF) treatment using external coils and a thumb spica cast. The mean time from the onset of the fracture to treatment was 40 months. No concurrent operation was performed. Follow-up time averaged 8.4 months. Eight of nine fractures with avascular necrosis healed. Five of eight fractures in the proximal third healed. Twelve (75%) of 16 patients treated in short-arm thumb spica casts and PEMF healed versus 22 (92%) of 24 patients treated initially in long-arm thumb spica casts and PEMF. We have found PEMF to be a reliable alternative method of treating nonunited scaphoid fractures. Because of the low risk, simplicity of use, and reliability, we recommend its consideration in the treatment of undisplaced, nonunited fractures without carpal instability less than 5 years after the injury. Treatment should initially begin with a long-arm cast.

Adolescent↗
PubMed1996

Three-dimensional dental cast analyzing system using laser scanning.

The purpose of this article is to introduce the outline of our newly developed three-dimensional dental cast analyzing system with laser scanning, and its preliminary clinical applications. The system is composed of a measuring device with a slit-ray laser projector and two sets of coupled charged devised video cameras, an image processing unit, a 16-bit personal computer as a controller, and an engineering workstation as a post processor. The dental cast is projected and scanned with a slit-ray laser beam. The raster coordinates of the target are determined with an image processor. Triangulation is applied to determine the location of each point. Generation of three-dimensional graphics of the dental cast takes approximately 40 minutes. About 90,000 sets of X, Y, Z coordinates are stored in the main memory of the microcomputer. The measurement error is less than 0.05 mm. Besides the conventional linear and angular measurements of the dental cast, we are also able to demonstrate the size of the palatal surface area and the volume of the oral cavity. The advantage of this system is that it facilitates the otherwise complicated and time-consuming mock surgery necessary for treatment planning in orthognathic surgery.

Computer Graphics↗
PubMed1996

Simple or repeated induction of superovulation: a study on ovulation rates and microvessel corrosion casts in ovaries of golden hamsters.

Repeatedly stimulated ovaries are reported to decrease the ovulation rate. One cause among others might be that the microvascular bed has been insufficiently developed. Therefore, 30-day-old golden hamsters were superovulated either once or repeatedly. At the light microscopic level, the ovulation rate in serially sectioned ovaries was indirectly determined by the occurrence of corpora lutea and of abnormal follicle rupture with oocyte release into the cortical stroma (IOR). For the study with scanning electron microscopy (SEM), the microvascular bed of the ovaries was cast with a polyester resin, and the corrosion casts of mature follicles observed. The histological sections of once-stimulated ovaries showed a large number of corpora lutea and IOR follicles. This indicated hyperovulation. In corrosion casts of once-stimulated ovaries, large-sized antral follicles with two layers of a dense capillary meshwork were observed. Capillary sprouts were aligned around the antrum 0 to 12 h after administration of human chorionic gonadotrophin (hCG), and these radiated towards the center of the antrum after 12 to 36 h had elapsed. The ovulation site was recognized at the follicle apex by three similarly sized structures which were either a sinusoid, an oocyte replica, or an opening. Repeatedly stimulated ovaries produced a low number of corpora lutea and almost no IOR follicles. This was judged as hypoovulation. The microvessels of mature follicles were reduced in number and incompletely cast. Widespread resin leakages were conspicuous in the follicle wall 36 h after hCG injection, but the capillary sprouts radiated towards the center of the antrum. No ovulation site was detectable. It is concluded, that capillary sprouts are induced before luteinization. The ovulation site is indicated by particular changes in its microvascular bed. An insufficiently developed microvascular bed may be responsible for hypoovulation in repeatedly stimulated ovaries.

Animals↗
PubMed2003

Botulinum toxin with and without casting in ambulant children with spastic diplegia: a clinical and functional assessment.

This study compared clinical and functional outcomes after treatment with botulinum toxin A (BTX-A) and BTX-A with casting in children with dynamic equinus foot. Ten children (seven males, three females; mean age 6 years 4 months, SD 2 years 7 months; range 4 to 11 years) with mild spastic diplegia and independent walking were divided into two groups: group 1, BTX-A and group 2, BTX-A plus casting. BTX-A was injected in the triceps surae bilaterally at multiple sites while the children were sedated with mask anaesthesia. Dysport toxin was used, 15 to 20 IU/kg in each muscle. Immediately after injection an ankle-foot orthosis was applied to children in group 1 and a cast to children in group 2. Clinical assessment using the Ashworth scale, Gross Motor Function Measure (GMFM), range of movement measurement, and gait analysis was performed before treatment and 1, 4, and 12 months after treatment. Spasticity decreased significantly at 1-month examination in both groups (p = 0.002), at 4-month examinations (Wilcoxon test p = 0.003), and 12 month (p = 0.052) examinations in group 2. GMFM highlighted a significant improvement in group 2 at the 4-month examination (p = 0.052 for standing,p = 0.007 for walking). Gait analysis showed a significant increase in the walking speed in group 2 (p = 0.04). No change was detected in ankle kinematics and kinetics or in muscular activity during the gait cycle. We confirmed that BTX-A reduces spasticity and improves functional performance in standing and walking; association with casting provides more marked and enduring results.

Ankle↗
PubMed2005

Long-range ordered thin films of block copolymers prepared by zone-casting and their thermal conversion into ordered nanostructured carbon.

Large-scale alignment of lamellae in thin films of diblock copolymers containing polyacrylonitrile and poly(n-butyl acrylate) was achieved by casting copolymer solution on a silicon substrate moved away at a constant speed from the casting nozzle (zone-casting). Grazing incidence small-angle X-ray scattering revealed that the lamellae, which were perpendicular to the substrate, were also aligned over macroscopic scale in the direction perpendicular to the casting direction. Such long-range ordered block copolymer films were then converted by pyrolysis into nanostructured carbons, with excellent preservation of lamellar morphology and orientation.

Acrylates↗
PubMed2005

Study of the casting of sulfonated polyimide ionomer membranes: structural evolution and influence on transport properties.

A casting process has been studied for charged polymers: the sulfonated polyimide ionomer membrane. The formation of the membrane has been followed by X-ray reflectivity as a function of temperature. The effect of equivalent weight has been also investigated. The thickness loss presents two regimes: the first one is linear vs time indicating that the models developed for noncharged polymer may be suitable for ionomers in the early period of drying. The second one corresponds to the loss of X-ray reflectivity signal. Moreover, the X-ray reflectivity signal seems to be correlated to the characteristic time of the sample drying. In complement, we have studied the influence of casting on the properties of the dried ionomer membranes. The transport coefficients of N(CH(3))(4)(+) ions confined in two kinds of membranes that were differently cast were measured. The results show that shearing the ionomer solution during casting may lead to an enhancement of the anisotropy of structure and of transport. Moreover, we have studied the effect of both interfaces on the ion transport properties through the dried membranes.

Journal Article↗
PubMed1993

Tensile properties of free films cast from aqueous ethylcellulose dispersions.

Free films of two commercially available formulations of aqueous ethylcellulose dispersion differing only in plasticizer content (Sure-lease/E-7-7050 without silica and E-7-7060 containing dibutyl sebacate and glyceryl tricaprylate/caprate as plasticizers, respectively) were cast and coalesced at temperatures ranging between 30 and 70 degrees C. Mechanical properties of these films were measured using tensile stress analysis. Three mechanical parameters, namely, tensile strength, work of failure, and elastic modulus, were computed from the load-time profiles of these films. The results showed that the tensile strength and elastic modulus values of the films cast from both formulations increased with the corresponding increase in coalescence temperature up to 60 degrees C, beyond which no significant differences were observed. In the case of work of failure, however, the difference between the two formulations was observed above 60 degrees C. The films cast from Surelease/E-7-7050 formulation without silica (dibutyl sebacate as the plasticizer) were relatively softer than those from Surelease/E-7-7060 formulation (glyceryl tricaprylate/caprate as the plasticizer). At coalescence temperatures above 50 degrees C, the films cast from both formulations exhibited temperature-dependent plastic deformation.

Cellulose↗
PubMed2002

Effect of heat treatment with the mould on the super-elastic property of Ti-Ni alloy castings for dental application.

Tensile property of Ti-50.85Ni (mol %) alloy castings was investigated quantitatively in relation to the thermal behavior accompanied with phase transformation to evaluate the effect of heat treatment after casting with the mould in air. The heat treatment temperature was 713 or 773 K, and the period was 0.9, 1.8, or 3.6 ks. Apparent proof stress of the castings decreased with increasing period of heat treatment, and the decrease was larger with the treatment at 773 K. Residual strain also decreased by the heat treatment, however, it was low with the treatment for relatively short period, i.e. 713 K-0.9 and 1.8 ks, and 773 K-0.9 ks treatments. From the thermal behavior measured by differential scanning calorimetry (DSC), the ascent in the transformation temperatures and the increase in the thermal peak height appeared to influence the changes in the tensile property. These changes by heat treatment were believed to be effective to utilize more flexibility, less stress and less permanent deformation in dental castings.

Journal Article↗
PubMed1993

Dental anomalies--are adhesive castings the solution?

Adhesive cast restorations placed without tooth preparation were used to restore the teeth of patients affected by either amelogenesis or dentinogenesis imperfecta. Twelve patients aged between 7 and 18 years were treated and in total 64 cast restorations were placed. At the time of cementation, the vertical dimension was increased by the thickness of restorative material placed on the functioning surfaces of the restored teeth. Full occlusion was restored for all individuals, with only one casting being lost. The castings have been placed for intervals between 10 and 54 months.

Acrylic Resins↗
PubMed1991

The design of CAST (Computer-Aided Speechreading Training).

The underlying theoretical assumptions, goals, design, and implementation of a Computer-Aided Speechreading Training system (CAST) are described as a case study in program design. This computerized speechreading assessment and training system simulates face-to-face intervention and is designed to be one component of a comprehensive aural rehabilitation program for preretirement adults with acquired mild-to-moderate hearing loss. The interactive, automated course consists of eight training lessons, each focusing on a particular viseme that is practiced by a modified discourse tracking method using viseme-specific texts. Three basic speechreading skills are emphasized: visual speech perception, use of linguistic redundancy, and use of feedback between message sender and receiver. These skills are evaluated separately by means of CAST tracking rate, receiver strategy, and inferred error type. Four example case assessments are provided to illustrate the potential applications of CAST as a standardizable rehabilitative tool. An independent program evaluation is provided in a companion paper (Gagné, Dinon, & Parsons, 1991). Comparisons between CAST, face-to-face tracking procedures, and natural discourse are presented and discussed with reference to theoretical and clinical issues in speechreading and program evaluation.

Computer-Assisted Instruction↗
PubMed1999

Local variations of the chemistry in as-cast gamma-TiAl (TiBx) alloys and its consequence for thermomechanical treatments

The first part of the paper presents an accompanying investigation to a thermomechanical processing route of gamma-TiAl turbine blades. By means of scanning electron microscopy and energy dispersive X-ray (EDX) analysis, the chemical homogeneity and the microstructures of gamma-TiAl as-cast ingots, work pieces and the final turbine blades are determined. We find that the local Al-content in as-cast ingots can vary by more than 1.5 at.%. Large chemical inhomogeneities present in as-cast ingots can only be eliminated to a certain degree by subsequent thermomechanical processing. An additional aim of the study is to assess the influence of a thermomechanical processing on the morphology of titanium boride precipitates and the alpha2-Ti3Al-phase. The second part of the paper contains a detailed analytical study devoted to homogenization of a range of gamma-TiAl cast alloys. Different microstructures are generated in a laboratory-scale argon-arc furnace by both rapid and slow solidification rates and an additional homogenization treatment, respectively. Quantitative EDX analysis shows that only rapid solidification of ingots with a subsequent homogenization treatment leads to a nearly chemically homogeneous microstructure.

Journal Article↗