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At least 1,621 records · Page 90Linked to original sources
PubMed1999

Silica coatings formed on noble dental casting alloy by the sol-gel dipping process.

The sol-gel dipping process, in which liquid silicon alkoxide is transformed into the solid silicon-oxygen network, can produce a thin film coating of silica (SiO2). The features of this method are high homogeneity and purity of the thin SiO2 film and a low sinter temperature, which are important in preparation of coating films that can protect from metallic ion release from the metal substrate and prevent attachment of dental plaque. We evaluated the surface characteristics of the dental casting silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy coated with a thin SiO2 film by the sol-gel dipping process. The SiO2 film bonded strongly (over 40 MPa) to Ti-implanted Ag-Pd-Cu-Au alloy substrate as demonstrated by a pull test. Hydrophobilization of Ti-implanted/SiO2-coated surfaces resulted in a significant increase of the contact angle of water (80.5 degrees) compared with that of the noncoated alloy specimens (59.3 degrees). Ti-implanted/SiO2-coated specimens showed the release of many fewer metallic ions (192 ppb/cm2) from the substrate than did noncoated specimens (2,089 ppb/cm2). The formation of a thin SiO2 film by the sol-gel dipping process on the surface of Ti-implanted Ag-Pd-Cu-Au alloy after casting clinically may be useful for minimizing the possibilities of the accumulation of dental plaque and metal allergies caused by intraoral metal restorations.

Adhesiveness↗
PubMed1991

Hypophyseal angioarchitecture of common tree shrew (Tupaia glis) revealed by scanning electron microscopy study of vascular corrosion casts.

The vascular corrosion cast technique in conjunction with scanning electron microscopy (SEM) was used for the study of pituitary microvascularization in the common tree shrew (Tupaia glis). The pituitary vascular casts were obtained by infusion of low viscosity methyl methacrylate plastic (Batson's no.17) mixture. It was found that the blood supplies to the pituitary complex were from branches of the circle of Willis and could be divided into two groups. The first group consisted of two to four superior hypophyseal arteries (SHAs) branching off from the internal carotid artery supplying each half of the median eminence (ME), infundibular stalk (IS), and pars distalis (PD). The SHAs supplying the ME branched into internal and external capillary plexi. The internal plexus had a larger capillary size (approximately 15 microns in diameter), was deeper in position, and had denser and more complex capillary loops than those in the external plexus. The capillaries of the external plexus were approximately 10 microns in diameter. The two plexi drained into 15-20 hypophyseal portal veins (HPVs) which were located mainly along the ventral and ventrolateral surfaces of the IS before breaking up into large capillaries (approximately 18 microns in diameter) with an anteroposterior arrangement within the PD. The second group consisted of one inferior hypophyseal artery (IHA) on each side branching off from the internal carotid artery. These arteries gave off branches to pierce the dorsolateral and ventrolateral aspects of infundibular process (IP) before branching off to form a capillary network. They also gave rise to radiating capillaries to supply the pars intermedia (PI) surrounding the cortical area of the IP. The hypophyseal cleft separating the PI from the PD was clearly seen with very few blood vessels. The capillaries in both PD and IP joined to form confluent hypophyseal veins draining the blood into the cavernous sinus.

Animals↗
PubMed1993

Bronchoalveolar casting using formalin-fixed canine lungs and a low viscosity silicone rubber.

A method for creating tough, flexible, bronchoalveolar casts from formalin-fixed canine lung is described. A lung was washed using simple methods and fixed in 10% neutral-buffered formalin. While still wet with formalin, an intact lobe was injected with silicone sealant, Silastic 734 RTV (Room Temperature Vulcanizing), using a caulk gun. Following digestion with protease and corrosion with potassium hydroxide, a bronchoalveolar cast was recovered giving detail as shown using scanning electron microscopy or conveniently seen by stereo light microscopy. This method should be useful for micro-anatomy studies of normal and diseased lungs.

Animals↗
PubMed2003

Embryonic development of coronary vasculature in rats: corrosion casting studies.

The aim of this study was to analyze the development of coronary vessels at different stages of embryonic life in rats using corrosion casts and scanning electron microscopy (SEM). We studied morphologic details of vessel maturation, expansion, and pattern formation from the stage of development when the coronary system forms patent connections with the aorta and the right atrium (embryonic day 16 (ED16)) to full-term fetus (ED21). The internal surface morphologies of the arterial and venous vessel walls were different and were dependent on the distance from the orifice and the capillary system. They also depended on the maturation state of a given vessel. In various branches of the coronary system we demonstrated round, fusiform or polygonal, endothelial cell imprints. The capillary network was dense, however, at the early stages of development, it formed a thin layer over the myocardium. By ED21 capillaries assumed an orientation parallel to the long axes of the cardiac myocytes. During all stages of development, different forms of angiogenesis by intussusceptive growth were observed. Splitting of the vessel wall occurred in two or three points along the vessel, forming two- or three-link chains. Certain areas of vessels resembled doughnuts, from which several sister vessels originated. The coronary arteries were situated deep within the myocardial wall. The major coronary veins were mostly located on the surface of the capillary plexuses of the myocardial wall. In conclusion, this method of vessel casting enables the detection of angiogenesis by intussusceptive growth, and the visualization of a capillary's position to the myocardial wall, thickness of the capillary plexuses, and the internal surface morphology of major vessels.

Animals↗
PubMed2002

Machinability of cast commercial titanium alloys.

This study investigated the machinability of cast orthopedic titanium (metastable beta) alloys for possible application to dentistry and compared the results with those of cast CP Ti, Ti-6Al-4V, and Ti-6Al-7Nb, which are currently used in dentistry. Machinability was determined as the amount of metal removed with the use of an electric handpiece and a SiC abrasive wheel turning at four different rotational wheel speeds. The ratios of the amount of metal removed and the wheel volume loss (machining ratio) were also evaluated. Based on these two criteria, the two alpha + beta alloys tested generally exhibited better results for most of the wheel speeds compared to all the other metals tested. The machinability of the three beta alloys employed was similar or worse, depending on the speed of the wheel, compared to CP Ti.

Alloys↗
PubMed1977

Porosity in the base metal removable partial denture casting alloys relative to observable metallographic features.

A series of tensile test pieces of the dimensions stated in the American Dental Association Specification No. 14 were produce using both nickel-base and cobalt-base removable partial denture casting alloys. Normal dental casting techniques were employed. Appropriate sections from each specimen were sectioned to half of their original thicknesses, embedded in heat-and pressure-cured conducting mounts, and polished for metallurgical examination. A double electrolytic etching technique was used, employing serially two solutions, in order to maximize the amount of metallographic detail visible. The method proved particularly valuable in the case of the nickel-base alloy as it indicated the presence of considerable interdendritic segregation. The incidence of porosity was evaluated throughout all sections of the specimens and, although found to be especially prevalent in those regions where gross shrinkage effects might be expected to occur, it was also shown to have a diffuse intergranular and interdendritic distribution.

Chromium Alloys↗
PubMedDate not supplied

The biocompatibility of a dental Ag-Pd-Cu-Au-based casting alloy and its structural components.

The biocompatibility of type III casting gold alloy, an Ag-Pd-Cu-Au-based dental casting alloy and its two main structural components, a CuPd-rich and an Ag-rich phase, was studied after subcutaneous implantation for 7 weeks in 20 guinea pigs. The Ag-Pd-Cu-Au alloy was surrounded by a capsule of immature collagen with fibroblasts and an increased vascular supply. The CuPd-rich component induced and maintained an acute inflammation with highly vascularized granulation tissue. The tissue reaction to the Ag-rich component and the Au-based alloy was slight. Ten of the guinea pigs were sensitized to PdCl2 prior to the implantation period, but this caused no enhanced tissue reaction, except for an increase in the number of mast cells around three of the alloys.

Animals↗
PubMed2006

A new method for the joint visualization of vascular structures and connective tissues: corrosion casting and 1 N NaOH maceration.

Corrosion casting combined with scanning electron microscopy (SEM) has been widely used to study the morphofunctional aspects of microcirculation in many organs. In this study, we present an optimization of the corrosion casting (CC) technique associating it with NaOH 1 N maceration method to obtain a clear visualization of the relationships existing between the microvascular architecture of an organ and its extracellular matrix. Briefly, experiments were performed macerating the tissue previously injected with a low viscosity acrylic resin in 1 N NaOH and then observing it at SEM. In this study, we present an application of this technique to better evaluate the extracellular components of the vascular wall in medium-sized and capillary vessels both in skin and in kidney. The results obtained yielded clear images of the three-dimensional layout of medium-sized and capillary vessels in comparison with the extracellular environment. Furthermore, detailed information was obtained on the three-dimensional layout of fibers constituting the walls of venules, arterioles, and capillaries. In addition, the tubular collagenic structures surrounding the excretory tubules of the kidney and the dermal glands of the skin were depicted and their relationships with their vascular supply described in detail.

Animals↗
PubMed1992

Cast immobilization and tibial diaphyseal blood flow: an initial study.

The effect of cast immobilization on blood flow to the tibial diaphysis was studied by the microsphere method, both before and after casting of one hindlimb of adult New Zealand White rabbits. Preliminary studies were undertaken to investigate the possibility of the reduction of tibial flow by the microspheres used for the control measurements of blood flow. There were no significant differences in the flows to the tibial diaphysis or skeletal muscle between the immobilized and control limbs after either 1 or 2 weeks. This similarity between control and experimental limbs indicates that immobilization had no major effect on tibial blood flow over and above the systemic effects of the procedure.

Animals↗
PubMed1992

Halo-cast treatment of fractures and dislocations of the cervical spine.

Twenty-eight consecutive patients with dislocated, and often unstable, injuries of the cervical spine were treated by halo-cast stabilisation. One died and 27 were followed up. Twenty had no symptoms and 17 had full movement of the neck. There were only a very few minor complications. Seven patients had initial neurological impairment. They included the single death, but the remaining 6 regained useful muscle function. The halo-cast allows complete reduction in many types of fractures and dislocations, and good immobilisation is maintained.

Adolescent↗
PubMed1995

Microvascularization of the cerebellum in the turtle, Pseudemys scripta elegans (Reptilia). A scanning electron microscope study of microvascular corrosion casts, including stereological measurements.

Cerebellar blood supply and microvascular patterns were studied in 12 freshwater turtles Pseudemys scripta elegans by scanning electron microscopy (SEM) of microvascular corrosion casts and histology. Vascular densities were estimated by point counting methods from casts and thin sections (7 microns). Short A2-arterioles and recurrent branches from A3-arterioles supply the capillary bed of the molecular layer, while V2 and V3 venules drain it. The Purkinje cell layer is supplied by horizontal branches ("parallel arteries") of A4 and A3 arterioles, which capillarize toward the granular and molecular layers. V2, V3 and V4 venules drain the areas supplied by A3 arterioles. The deep granular and subependymal layers are supplied by A4 arterioles, those adjacent to the Purkinje cell layer also by A3 arterioles. The areas supplied by A4 arterioles drain via V4 venules. The granular and Purkinje cell layers taken together have an estimated vascular density of 4.1%, while in the molecular layer this value is 3.3%. Our findings largely confirm published data from Testudo geometrica and Pseudemys scripta elegans with respect to gross supply and drainage. The microvascular patterns are similar to those of the human cerebellar cortex, particularly the basic patterns of intracortical arterioles and venules. The molecular layer, like that in the human brain, has a circulatory bed largely independent of that of the Purkinje cell and granular layers. In contrast to the human brain, a cerebellar pial capillary network is present in the brain of the turtle.

Animals↗
PubMed1996

Treatment of isolated distal ulnar shaft fractures with below-elbow plaster cast. A prospective study.

In a prospective study 52 patients with an isolated fracture of the distal ulna were treated with a below-elbow plaster cast. The histories of 46 patients were reviewed after a mean follow-up of 3.5 years (ranging from 10 months to 7 years). Forty-three fractures united. There were two non-unions. One fracture displaced while in the plaster, so that there was no longer any bone contact between the fragments. The fracture was consequently treated by open reduction and internal fixation. The type of fracture, the initial displacement (all fractures had bone contact) or the initial angulation (maximum 10 deg) was not found to influence the final clinical results. Below-elbow plaster cast appeared to produce satisfactory results in 89% of the patients.

Adult↗
PubMed1991

Observation of microvascular casts of human hepatocellular carcinoma by scanning electron microscopy.

The microcirculation of hepatocellular carcinomas (HCCs) and surrounding tissue was observed three-dimensionally by scanning electron microscopy of vascular casts made from 10 livers at autopsy. The livers were perfusion-washed and cast with resin through both the hepatic artery and portal vein branches. The HCCs observed ranged from several millimeters to 3 cm in size. A vascular plexus proliferated around the HCC nodules in all cases. Both portal vein and hepatic artery branches proliferated markedly to form the plexus in 5 patients. These vessels communicated directly with the blood sinuses of the HCCs as feeder vessels. HCC cells replaced normal cells while maintaining the liver's trabecular structure in 2 cases. At the borders of these HCCs, there was direct communication between the hepatic sinusoids and the tumor blood sinuses. Efferent vessels of the tumors were generally difficult to identify but vessels resembling hepatic vein branches were detected in one 4-mm HCC nodule after microdissection. Thus, HCC was demonstrated to be supplied not only by the hepatic artery but also by the portal vein and hepatic sinusoids. This may be one of the reasons why cancer cells survive in the tumor margins and daughter nodules after transcatheter arterial embolization of HCC.

Adult↗
PubMed2000

Do Colles' fracture patients benefit from routine referral to physiotherapy following cast removal?

Colles' fracture patients who received physiotherapy immediately following cast removal were compared with patients who received no active therapy following cast removal in a prospective randomised study. Patients who attended physiotherapy achieved significantly greater increases in wrist extension and grip strength after 6 weeks compared to patients who received no active therapy.

Aged↗
PubMed2005

Retrospective analysis of casts to assess cervical headgear treatment in the presence of vertical growth pattern.

OBJECTIVE: Does molar distalization as effected by cervical headgear increase the vertical dimension of occlusion in patients with vertical growth pattern? MATERIALS AND METHODS: A sample of 86 patients with neutral and vertical growth pattern in the late mixed dentition stage underwent headgear treatment. Their initial and intermediary casts were retrospectively analyzed for occlusal relationships at the maxillary first molars and degrees of overjet and overbite. The only cases included were those in which headgear treatment was carried on for at least 6 months, achieving a minimum distalization of 4 mm. The intermediary casts were fabricated after headgear treatment had been completed and prior to the initiation of multiband treatment. Patients were divided into three groups (N, V1 and V2) according to the degrees of vertical growth pattern, which were determined based on y-axis angle values. RESULTS: Grouped by degrees of vertical growth, the data revealed occlusal relationship changes of 6-8 mm and overjet reductions of 0.6-1.2 mm. The overbite changes were unexpectedly small (0-0.04 mm). Grouped by degrees of overbite, the data revealed that headgear treatment increased the vertical dimension of occlusion in deep-bite patients (>4 mm), while giving rise to decreases in patients with overbites of <3 mm.

Adolescent↗
PubMed2002

Treatment of complete rupture of the lateral ligaments of the ankle: a randomized clinical trial comparing cast immobilization with functional treatment.

This study compared the therapeutic efficacy between cast immobilization and functional treatment of grade III ruptures of the lateral ankle ligaments. Subjects ( n=121) had closed physeal cartilage, age under 35 years, grade III rupture without previous or associated injuries, and practiced regular sports. Patients were randomized into an immobilization group (21 days plaster cast) or a functional one (15 days strapping plus early controlled mobilization). Symptoms (pain, swelling, stiffness, subjective instability), joint laxity, return to preinjury activity (time and level) and rate of reinjury were assessed 3, 6, and 12 months after sprain. Objective joint laxity was related to constitutional laxity, creating a new variable [talar tilt at injury - talar tilt at control]/contralateral talar tilt. The functional group showed significantly earlier and better return to physical activity, fewer symptoms at 3 and 6 months but no intergroup difference at 12 months. Functional treatment also showed better decrease in joint laxity. No intergroup differences were found in the reinjury rate. We conclude that functional treatment is safe, associated with a more rapid recovery, and particularly suitable in athletic populations.

Adolescent↗
PubMed2003

Immediate mobilization gives good results in boxer's fractures with volar angulation up to 70 degrees: a prospective randomized trial comparing immediate mobilization with cast immobilization.

BACKGROUND: The management of the subcapital fracture of the fifth metacarpal bone, the boxer's fracture, is still a matter of debate. Besides the question of which rate of angulation is acceptable before a reduction becomes necessary, recommendations for further treatment of this fracture vary as well. Therefore, the aim of our study was to compare randomly and prospectively the results of an immobilization treatment for 3 weeks with cast with a functional treatment, all with accepted angulations up to 70 degrees. PATIENTS AND METHODS: Between June 1997 and June 1998, 40 patients were randomly allocated either to treatment with an ulnar gutter plaster cast for a period of 3 weeks followed by mobilization, or a pressure bandage for 1 week and immediate mobilization within limits imposed by pain. All patients were monitored at the outpatient clinic 6 and 12 weeks after the fracture. Clinical outcome was measured by the range of motion (ROM) of the fifth metacarpal phalangeal (MCP) joint, and by interviewing the patients about their satisfaction, pain perception, return to work and hobby, and need for physiotherapy. RESULTS: A total of 35 patients with a mean age of 29 years (range 15-84) completed the required follow-up program. The mean angulation of the fracture was 39 degrees (range 15-70 degrees ). Between the two groups, no statistical differences were scored with respect to ROM, satisfaction, pain perception, return to work and hobby, and need for physiotherapy. According to a sample size calculation (power 90%, alpha 0.05, to detect 5 degrees difference in ROM), 12 patients needed to be included in each group to reach significance. CONCLUSIONS: A pressure bandage for 1 week, followed by immediate mobilization, is a sufficient alternative treatment for a boxer's fracture, if it is not angulated greater than 70 degrees and not rotated. This treatment resulted in satisfied patients who perceived no more pain and had a good ROM of the fifth MCP joint. Reduction of angulated fractures of less than 70 degrees seems not of value, with respect to ROM of the fifth MCP joint.

Adolescent↗
PubMed1999

Longevity of cast gold inlays and partial crowns--a retrospective study at a dental school clinic.

From 1963 to 1993, 890 patients were treated with 3518 cast gold restorations by students and postgraduate dentists. The longevity of these restorations was studied retrospectively using the patient files. Longevity was calculated using the method described by Kaplan and Meier. After the observation period, 111 (3.2%) of the examined restorations were not in place anymore. The most frequent reasons for failure were caries (33.7%), lack of retention (32.7%), endodontic treatment (29.6%), insufficient marginal adaptation (3.1%) and extraction (1%). The cumulative survival rate and a 95% interval of confidence was calculated for all restorations and for each of the locations and surfaces included in the trial. The 10-year survival rate for occlusal inlays was, 76.1% (12.1) for MO inlays 88.3% (4.2), for DO inlays 83.4% (4.6), for MOD inlays 87.5% (2.4), for partial crowns 86.1% (3.3) and 85.7% (1.7) for all restorations. Based on the statistical method used, the cast gold restorations demonstrated satisfactory longevity results.

Adult↗