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PubMedDate not supplied

An evaluation of fiberglass cast application techniques.

Cylindrical casts constructed from 2, 3, 4, and 5 inch widths of fiberglass casting material were evaluated for strength in bending using an unstable fracture model. Five-inch casting material produced the strongest casts. The effect of longitudinal splinting with 2-inch fiberglass tape was evaluated in cylindrical casts constructed from 4-inch tape. Casts with splints on the compression side or with splints on both the tension and compression sides were stronger in bending than casts with a single splint on the tension side or casts without splints.

Animals↗
PubMed1997

Three-dimensional analysis of vasospastic major cerebral arteries in rats with the corrosion cast technique.

BACKGROUND AND PURPOSE: Although mice, rats, and other small animals are commonly used for molecular biology research, their use in the evaluation of cerebral vasospasm after subarachnoid hemorrhage is somewhat problematic because of the correspondingly small size of their cerebral vessels. We have already reported that the corrosion cast technique was useful for evaluating newly formed cerebral vessels in neural grafts in these small animals. In the present study we applied the corrosion cast technique to the evaluation of hemolysate-induced cerebral vasospasm in rats and performed three-dimensional analysis for comparison. The casting was done 10 minutes after the hemolysate injection, so that only acute "vasospasm" was assessed. METHODS: After withdrawal of 0.1 mL cerebrospinal fluid, 0.2 mL hemolysate (n = 9) or saline (n = 10) was injected into the cisterna magna of male Sprague-Dawley rats weighing between 300 and 350 g. Ten minutes later, perfusion of a semipolymerized casting medium was performed at an injection pressure of 100 to 120 mm Hg. The brains were immersed and corroded in 10% NaOH solution. After these procedures, the basilar artery as well as peripheral vessels was analyzed morphologically with scanning electron microscopy. Conventional histological analysis with the use of paraffin-embedded section with hematoxylin-eosin staining was also performed, and the results were compared with those for the corrosion cast methods. RESULTS: In the saline-injected group, SEM showed that the inner surface of the basilar artery was smooth and the form of the endothelial cell was printed on the surface of the cast. In the hemolysate-injected group, the basilar artery showed an apparent vasospasm over its entire length, and corrugation was observed on the inner surface of the basilar artery in a three-dimensional fashion. Higher magnification revealed that the nuclei of the endothelial cells were distorted. Local narrowing of the basilar artery and vasospasm in the arteries of the anterior circulation and in peripheral arteries were also observed. Measurement of the inner diameter of the basilar artery showed 37.8% contraction in the hemolysate-injected group compared with the saline-injected group by the corrosion cast method. This degree of vasospasm was similar to that observed by the conventional histological method. CONCLUSIONS: In this report we show that detailed three-dimensional observation in the rat can be performed qualitatively and quantitatively with the corrosion cast technique. We conclude that this method derives an accurate measurement of the diameter of rat major cerebral arteries and is more reliable for analyzing vasospasm in rats than angiography and other conventional procedures.

Animals↗
PubMed1985

Walking casts: effect on plantar foot pressures.

Pressure measurements were made at four sites on the right foot of six normal subjects while they walked in a standard shoe, conventional padded cast, total contact cast, and again in a shoe. No differences in mean relative pressure were found between the padded cast and the total-contact cast. Significant reductions in mean relative pressure were found between the standard shoe and walking casts at the first and third metatarsal head. This study supported the use of walking casts in the management of plantar ulcers. The effectiveness of the cast in reducing plantar pressure was not found to be dependent on the cast padding technique.

Casts, Surgical↗
PubMed2003

Use of a cast compared with a functional ankle brace after operative treatment of an ankle fracture. A prospective, randomized study.

BACKGROUND: Controversy continues with regard to the optimal postoperative care after open reduction and internal fixation of an ankle fracture. The hypothesis of this study was that postoperative treatment of an ankle fracture with a brace that allows active and passive range-of-motion exercises would improve the functional recovery of patients compared with that after conventional treatment with a cast. Thus, the purpose of this prospective, randomized study was to compare the long-term subjective, objective, and functional outcome after conventional treatment with a cast and that after use of functional bracing in the first six weeks following internal fixation of an ankle fracture. METHODS: One hundred patients with an unstable and/or displaced Weber type-A or B ankle fracture were treated operatively and then were randomly allocated to two groups: immobilization in a below-the-knee cast (fifty patients) or early mobilization in a functional ankle brace (fifty patients) for the first six postoperative weeks. The follow-up examinations, which consisted of subjective and objective (clinical, radiographic, and functional) evaluations, were performed at two, six, twelve, and fifty-two weeks and at two years postoperatively. RESULTS: There were no perioperative complications in either study group, but eight patients who were managed with a cast and thirty-three patients who were managed with a brace had postoperative complications, which were mainly related to wound-healing. Two patients in the group treated with a cast had deep-vein thrombosis. All fractures healed well in both groups. The difference between the two groups with respect to the complication rate was significant (p = 0.0005). No significant differences between the study groups were observed in the final subjective or objective (clinical) evaluation. At the two-year follow-up examination, the average score (and standard deviation) according to the ankle-rating scale of Kaikkonen et al. was 85 +/- 9 points for the group treated with a cast and 83 +/- 10 points for the group treated with a brace, and the average ankle score according to the system of Olerud and Molander was 87 +/- 8 points and 87 +/- 9 points, respectively. CONCLUSIONS: The long-term functional outcome after postoperative treatment of an ankle fracture with a cast and that after use of a functional brace are similar. Although early mobilization with use of a functional ankle brace may have some theoretical beneficial effects, the risk of postoperative wound complications associated with this treatment approach is considerably increased compared with that after conventional cast treatment. Thus, the postoperative protocol of treatment with a functional brace requires refinement before it can be generally advocated for use after operative treatment of an ankle fracture.

Adult↗
PubMed2006

Use of transfixation pin casts to treat adult horses with comminuted phalangeal fractures: 20 cases (1993-2003).

OBJECTIVE: To determine the clinical applications, short and long-term survival, and complications of using transfixation pin casts for treatment of comminuted phalangeal fractures in adult horses. DESIGN: Retrospective case series. ANIMALS: 20 horses. PROCEDURES: Medical records were reviewed to obtain information regarding signalment, fracture location, treatment methods, complications, and short-term survival (discharge from hospital). Long-term follow-up information was obtained via contact with owners or trainers. RESULTS: 12 fractures were in a hind limb, and 8 were in a forelimb. Fourteen fractures occurred in a middle phalanx, and 6 occurred in a proximal phalanx. Eleven fractures were treated with internal fixation combined with transfixation pin casts, and 9 fractures were treated with transfixation pin casts alone. Transfixation pin casts were maintained for a mean of 52 days (median, 49 days; range, 1 to 131 days). Fourteen (70%) horses were discharged from the hospital, whereas 6 (30%) were euthanized during the treatment period. Reasons for euthanasia included secondary fracture of the third metacarpal or metatarsal bone, avascularity of the distal aspect of the limb associated with an open fracture, and displacement of the fracture after transfixation pin cast removal. A significantly greater number of horses was discharged from the hospital when the transfixation pin cast was maintained for > 40 days, compared with those in which the transfixation pin cast was maintained for < 40 days. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that horses should be maintained in a transfixation pin cast for a minimum of 40 days, as this was associated with an increase in short-term survival without an increased risk of catastrophic failure.

Animals↗
PubMed1992

[Studies on marginal castability of cast crown].

The castability of the crown margins was studied. The smoothness and quantitative measurement of the margins were compared with the original wax patterns and their casted products. Wax patterns of the plate and crown forms were fabricated with sharp, straight and even margins. Margin angles of the wax patterns were prepared at both 20 and 40 degrees for the plate type and 20 degrees for the crown type samples. Each wax pattern was casted with Type IV gold alloy and gold-silver-palladium alloy. The casted margins were evaluated by comparing them with their original wax patterns. The results were as follows: 1. Compared to the current procedure, more precise evaluation of the marginal castability is now possible with this new method. 2. The shortness of the margins was observed in all of the casted samples. Casted samples with 20-degree margins resulted in twice as much deficiency as compared to those with 40-degree margins. 3. The smoothness and evenness of the margins were inferior in all of the casted samples when compared to their original wax patterns. 4. The margin thickness was between 50 and 70 microns when the wax patterns with sharp margins were casted. 5. A certain thickness is required at the margins of the wax patterns in order to achieve precise casted margins. In this study, it was found to be 79.1 microns.

Crowns↗
PubMed2000

Properties of a hybrid plaster-fibreglass cast.

OBJECTIVE: To examine the suitability of a plaster-fibreglass hybrid cast for orthopedic applications, comparing them to plaster of Paris (POP) and fibreglass constructs. METHOD: Groups of 10 standardized hybrid, POP and fibreglass casts were studied. An Instron servohydraulic system was used to test the casts in 3-point bending and shear. OUTCOME MEASURES: Strength, stiffness, weight, thickness and cost of the 3 types of cast, and shear strength at the interface between the POP and fibreglass in the hybrid casts. RESULTS: The hybrid casts were twice as strong as the POP constructs, were stiffer and weighed 14% less but were thicker and cost 2.5 times more. They were almost as strong as and less than half the cost of the fibreglass constructs but were thicker, not as stiff, and weighed 42% more. The shear strength of the POP-fibreglass interface in the hybrid casts was higher than the 3-point bending strength of this construct by a factor of 3. CONCLUSIONS: Plaster-fibreglass hybrid casts should be considered for orthopedic use on the basis of their strength, stiffness, weight and cost, combined with their acknowledged advantages of good moulding ability and water resistance.

Analysis of Variance↗
PubMed1997

[The effect of the mold temperature on the mechanical properties and reaction layer structure of the titanium castings].

Titanium is very reactive at the high temperature, easily oxidized, and reacts with investment components. The mold temperature is an important factor on the quality of the titanium castings. The paper investigated the effect of the mold temperature on the mechanical properties and reaction layer structure of the titanium castings with the tensile test and modern surface analysis technique. The results indicated that the tensile strength and yield strength of titanium castings increased but elongation rate decreased, and the hardness layer become thicker when the mold temperature raised. The hardness layer of titanium castings was 50 microns for the room temperature mold, 125 microns for the 850 degrees C mold. SX-macro electric probe analysis indicated the spreading depth of Zr, Al elements on the surface of titanium castings was not increased when the mold temperature raised, but, the spreading depth of Si element became deeper on the surface of titanium casting, Si layer was about 30 microns for the room temperature mold, 40 microns for the 250 degrees C mold, 50 microns for the 450 degrees C mold, 70 microns for the 650 degrees C mold, 90 microns for the 850 degrees C mold. So, it is necessary to consider the effect of the mold temperature on the qualities of titanium castings when titanium castings for prosthodontics were made in clinic.

Dental Casting Technique↗
PubMed2001

[The influence of two different casting temperatures on properties of the incorporated keeper].

OBJECTIVE: To probe the clinical possibility of making incorporated keeper cap by high temperature casting. METHODS: The incorporated keepers were equally divided into two groups, and cast by applying medium and high temperatures respectively. The two groups were compared with the following items: the morphological changes and thickness of keeper's oxide film, the combining quality between keeper and alloy, and the magnetic retention force. RESULTS: The two different casting temperatures had the similar influence on the keeper's properties, such as the keeper's metallographical view, magnetic force (medium temperature casting group: 433.6 g; high temperature casting group: 433.8 g), and combining quality with alloy, except for the morphology and thickness of the keeper's oxide film. The oxide films of the high temperature casting group (surface: 7.59 microns combining surface of keeper and alloy: 6.17 microns) were thicker than those of the medium temperature casting group (surface: 4.65 microns; combining surface of keeper and alloy: 3.95 microns). CONCLUSIONS: The incorporated keeper could be made by using high temperature casting method instead of medium temperature one in clinic.

Dental Casting Technique↗
PubMed2003

[Femoral shaft fracture in children: treatment with early spica cast].

PURPOSE OF THE STUDY: Fractures of the femoral shaft are frequent in children and prognosis is good. For children aged less than 7 years, most authors propose orthopedic treatment using prolonged traction then cast immobilization, or orthopedic reduction under general anesthesia and early cast immobilization. The purpose of the present work was to analyze results of orthopedic treatment using a spica early for children aged less than 7 years in comparison with other published series with similar age or management. MATERIAL AND METHOD: Forty-seven unselected children aged less than 7 years with a closed fracture of the femoral shaft were treated by orthopedic reduction under general anesthesia and immobilization with a spica cast after a short period (<48 hr) of traction in the plane of the bed. Hip immobilization was set in flexion and minimal abduction, knee in flexion. The children were discharged the day the cast was installed or the next day. Follow-up examinations (tolerance) with x-rays cast in place were scheduled for day 8 and day 15. Clinical and radiological assessment was also recorded at removal of the cast, at 3 months, at 1 year, and at maximum follow-up. RESULTS: Mean age was 37 months (range 2-83 months). Boys predominated (n=34, 73%). Mean duration of traction was 1.13 days (range 0-5 days). Mean duration of cast immobilization was 45.4 days (range 28-78 days). Mean hospital stay was 2.8 days (range 1-10 days). Four patients (8%) were rehospitalized for secondary displacement under the cast. Weight bearing was effective at day 49 (range 33-78). Mean follow-up was 12.1 months (range 3 months-6 years). Five children (10.5%) developed leg length discrepancy greater than 10 mm. The anatomic axis of the femur in the saggital and frontal planes exhibited deviation in 7 children measuring less than 8 degrees in all cases. DISCUSSION: The localization and type of fracture observed in this series of children was similar to that reported in epidemiological studies. There were no treatment-related complications. In respect to healing time, deviation, and residual leg length discrepancy, results in this series were equivalent to those reported by others, irrespective of the treatment method employed. The major advantage of early spica is a short hospital stay allowing cost containment and rapid return to the child's everyday environment.

Casts, Surgical↗
PubMedDate not supplied

Bending resistance of prefabricated titanium posts following molten cast core attachment.

Posts and cores are used to restore endodontically treated teeth that have substantial loss of the coronal tooth structure. This in vitro study was designed to determine the mechanical properties of prefabricated titanium posts following attachment of their metal cores by molten casting (caston). Prefabricated tapered titanium posts (ER post-restoring system, Komet, Lemgo, Germany) in three diameter sizes (ISO 50, 90, 110) (n=9) were cast over with the metal cores of three different alloys (Au-Ag-Pt, Au-Pt-Pd, Co-Cr-Mo). Also, posts of each size were precision fit into the central core channels of the different cast metal cores to serve as control specimens. The 0.2% yield strengths (R0.2) of all specimens were tested on a universal testing machine. Statistical analyses of the results were carried out with an analysis of variance (ANOVA, one-way, two-way) and Bonferroni-Dunn's multiple comparisons post-hoc analysis for test groups (alpha=0.05). There was a significant decrease in yield strength (p<0.05) as a result of casting the various metals over the different post sizes, considered to be due to the detrimental thickening and porosity formation of the titanium surface oxide layer. Twenty-one percent, 51% and 33% reduction in yield strength, respectively, was obtained for the ISO 50, ISO 90 and ISO 110 cast-on groups relative to controls (p<0.05). Statistically significant differences in various core alloys were found only for the Au-Ag-Pt alloy compared to the Co-Cr-Mo alloy (post size ISO 50) and the Au-Pt-Pd alloy compared to the Co-Cr-Mo alloy (post size ISO 110) (p>0.05). Prefabricated titanium posts with metal cores cast over them showed inferior mechanical properties compared to precision-fit posts. These results indicate greater strength of the titanium posts when their cast cores were attached mechanically rather than by the molten casting method.

Crowns↗
PubMed1985

Early motion with cast-brace after modified Coventry high tibial osteotomy.

The records of 31 patients who were treated by a modified Coventry high tibial osteotomy were reviewed, and the early results of postoperative management with a cylinder cast were compared with those with early motion in a cast-brace. Thirteen patients (15 knees) who had immobilization in a cylinder cast after surgery for an average of 44.3 days had lost a mean of 10 degrees of flexion at three months of follow-up study. Their average total hospitalization was 15.5 days. Eighteen patients (19 knees) treated by early motion in a cast-brace had not lost any preoperative flexion at three months of follow-up study. The two most recent of these patients received continuous passive motion in the immediate postoperative period. The average total hospitalization for this group was 10.7 days. One patient in the cast-brace group had a significant loss of correction at the osteotomy site during healing. Eleven of the patients treated by a cylinder cast (84.6%) and 17 of the patients managed with a cast-brace (94.4%) stated that they had been improved by the surgery at this early stage. There were no nonunions or loss of internal fixation in either of the two groups. Early motion in a cast-brace (with a continuous passive motion machine, if available) is safe and is comfortable for and well accepted by patients.

Adult↗
PubMed1996

Surface reaction between titanium castings and investments.

The selection of investments suitable for titanium castings is critical because the surface-reacted layer greatly affects their mechanical properties. This study analyzed the interfacial zone of titanium castings obtained from various commercial investments and examined the relationship between the surface-reacted layer and the hardness. CP titanium disks (20 mm diameter, 1 mm thick, n = 5) were cast using eight commercial casting systems and investments for titanium casting: two alumina-based investments (T-invest, CD-titan investment), two spinel-based investments (Titanmold, Titavest MZ), three zirconia-based investments (Asahivest-D, Titaniumvest EX, Tycast investment TM), and a magnesia-based investment (Selevest CB). The Vickers hardness of cast disks in cross-section was tested at 50 microns intervals from the surface to 0.5 mm in depth. The cross-section was observed metallurgically, and an elemental mapping measurement of the reacted layer was conducted under the EPMA. The Vickers hardnesses at 50 microns from the surface of the specimens ranged 312 to 624 and were significantly different among the investments (p < 0.01). The thickness of the reacted layer, rich in O, Si, Al, Zr, Mg, and P, ranged from 10 to 60 microns. No correlation was seen between the thickness of reacted layer and the hardness (p > 0.05). However, the specimens cast with alumina-based and zirconia-based investments were harder than the spinel-based and magnesia-based investments at 500 microns. Although the free energies of metal oxide formation of alumina and zirconia were lower than titania, these data suggest that silica, alumina and zirconia were reduced by contact with molten titanium. Accordingly, silicon, aluminum and zirconium diffused to the interior of the titanium castings and changed their mechanical properties.

Aluminum Oxide↗
PubMed1997

A laboratory evaluation of the construction of resin-bonded cast restorations.

OBJECTIVE: To compare the effect of two construction techniques and two pattern materials on the fit of resin-bonded cast restorations. DESIGN: In-vitro study carried out by one operator. SETTING: Postgraduate university hospital. SUBJECTS AND METHODS: 65 nickel-chrome castings were constructed using refractory die and lift-off techniques with wax and acrylic resin pattern material. They were cemented onto master silver dies, embedded in self-curing acrylic resin and sectioned along their long axes. Interfacial distance between the master silver die and casting was measured. RESULTS: A significant different between the range of figures in each group (Mann-Whitney Test, P < 0.01) was found. Construction techniques can be ranked in order of fit of castings: 1. Refractory die, wax patterns: 42.6 microns (SD 12.03). 2. Refractory die, acrylic resin patterns: 53.7 microns (SD.16.06).3. Conventional technique, acrylic resin patterns: 85.5 microns (SD 31.62). 4. Lift-off technique, wax patterns: 139 microns (SD 53.15).5. Lift-off technique, acrylic patterns: 172.8 microns (SD 74.04). CONCLUSIONS: Castings constructed using refractory die technique and subsequently cemented resulted in a more accurate and less variable fit than those produced with the lift-off technique. Wax patterns lead to more accurate castings than acrylic resin and locating indentations may interfere with the cementation of castings when lift-off techniques are used.

Acrylic Resins↗
PubMed1991

Dimensional accuracy of small gold alloy castings. Part 1. A brief history and the behaviour of inlay waxes.

Part 1 reviews published studies which relate to materials and techniques contributing to the dimensional accuracy of small dental castings. A brief history of the cire perdue or lost-wax method of casting alloys and the development of modern dental casting materials and techniques are presented. Data on the behaviour of inlay wax, in particular its contraction and distortion, are reviewed as is the extensive literature about the casting shrinkage of gold alloys (Part 2) and the setting and thermal expansion of investments under both laboratory and practical conditions (Part 3). Part 4 discusses the role of the casting ring and its asbestos liner. Asbestos as a liner has now largely been replaced by two alternative materials, one based on cellulose and the other on ceramic fibres. The limited literature on the effect of these newer materials on casting accuracy is also reviewed, as their introduction may require significant changes in the traditional technology of dental casting.

Dental Casting Investment↗
PubMed1989

Cast bronchitis in infants and children.

Seventy-two children (age range, 3 months to 5.5 years) with a clinical diagnosis of obstructive bronchitis (asthmatoid or spastic bronchitis or bronchiolitis) were found to have bronchial casts in the gastric fluid, and in 2 additional cases casts were spontaneously expectorated in the bronchial exudate. Cast bronchitis had a long-term course of 10 to 24 months in 65 of the 74 patients. Common radiologic findings included bronchi presumably filled with secretions, areas of atelectasis, and lung emphysema of varying degrees. Cast bronchitis did not appear to be associated with eosinophilia and elevated serum IgE levels. Therefore, an extrinsic allergic mechanism is not likely involved in the pathogenesis of the condition. Bronchial casts had varying consistencies; although they were usually soft, they were sometimes rather hard. They were hollow, often ramified, and white and measured from 0.5 to 2 cm in length. Histologically, they consisted of metaplastic squamous epithelium with a varying degree of inflammatory cells and noncellular material. Some differences in biochemical composition were observed between bronchial casts and bronchial exudate of acute catarrhal bronchitis. No viruses could be isolated in 11 cast specimens. Our results suggest that cast formation is mainly related to the metaplastic transformation of the bronchial epithelium and that this metaplasia may play an important pathophysiologic role in certain infants and children with obstructive bronchitis.

Bronchi↗
PubMed1985

The vascular pattern of basal cell tumors: light microscopy and scanning electron microscopic study on vascular corrosion casts.

Light microscopy of hematoxylin-eosin stained tissue sections and scanning electron microscopy (SEM) of vascular corrosion casts were used to study the blood vascular system of human basal cell tumors. Concerning the gross angioarchitecture there is a very close correlation between the histological appearance and the findings obtained from vascular corrosion casts, when evaluated in a SEM. The tumor cell beds are enveloped by basket-like capillary plexus. The tumors are traversed over long distances by superficially running, teleangiectatic, but flattened capillaries. These compressed vessels are squeezed between tumor cell cords and epidermis. In vascular corrosion casts of human basal cell tumors the vascular system exhibits three different features. Blind-ending vascular casts; Four different causes for blind-ending cast structures are pointed out and discussed. Incomplete filling of the vascular system; compression of tumor vessels; new proliferating capillary sprouts; broken cast endings. Variations in vessel caliber and extravasation of the injection resin. Most of the variation in vessel calibers are thought to be caused by dilation of the weakened endothelial walls, but some of them presumably represent new projecting vascular swellings. Circumscribed leakage of the injected resin could be attributed to regions of advanced connective tissue degeneration and endothelial lysis. Flattened cast structures; The addition of tissues during tumor growth results in an increase of tissue pressure. Thus many tumor vessels get displaced, compressed, and flattened and vascular occlusions will occur. However, it must be stressed that much caution is needed in assessing the nature of the vascular cast structures of basal cell tumors.

Basal Cell Carcinoma↗
PubMed2004

Independent origins of Indian caste and tribal paternal lineages.

The origins of the nearly one billion people inhabiting the Indian subcontinent and following the customs of the Hindu caste system are controversial: are they largely derived from Indian local populations (i.e. tribal groups) or from recent immigrants to India? Archaeological and linguistic evidence support the latter hypothesis, whereas recent genetic data seem to favor the former hypothesis. Here, we analyze the most extensive dataset of Indian caste and tribal Y chromosomes to date. We find that caste and tribal groups differ significantly in their haplogroup frequency distributions; caste groups are homogeneous for Y chromosome variation and more closely related to each other and to central Asian groups than to Indian tribal or any other Eurasian groups. We conclude that paternal lineages of Indian caste groups are primarily descended from Indo-European speakers who migrated from central Asia approximately 3,500 years ago. Conversely, paternal lineages of tribal groups are predominantly derived from the original Indian gene pool. We also provide evidence for bidirectional male gene flow between caste and tribal groups. In comparison, caste and tribal groups are homogeneous with respect to mitochondrial DNA variation, which may reflect the sociocultural characteristics of the Indian caste society.

Analysis of Variance↗