Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CASTS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
PubMed1998

Effects of joint configuration for the arc welding of cast Ti-6Al-4V alloy rods in argon.

STATEMENT OF PROBLEM: Titanium and its alloys are more commonly used in prosthodontics and welding has become the most common modality for their joining. Studies on the welding of titanium and its alloys have not quantified this value, though its importance has been suggested. PURPOSE: This study compared the strength and properties of the joint achieved at various butt joint gaps by the arc-welding of cast Ti-6Al-4V alloy tensile bars in an argon atmosphere. MATERIAL AND METHODS: Forty of 50 specimens were sectioned and welded at four gaps. All specimens underwent tensile testing to determine ultimate tensile strength and percentage elongation, then oxygen analysis and scanning electron microscopy. RESULTS: As no more than 3 samples in any group of 10 actually fractured in the weld itself, a secondary analysis that involved fracture location was initiated. There were no differences in ultimate tensile strength or percentage elongation between specimens with weld gaps of 0.25, 0.50, 0.75, and 1.00 mm and the as-cast specimens. There were no differences in ultimate tensile strength between specimens fracturing in the weld and those fracturing in the gauge in welded specimens; however, as-cast specimens demonstrated a higher ultimate tensile strength than welded specimens that fractured in the weld. Specimens that fractured in the weld site demonstrated less ductility than those that fractured in the gauge in both welded and as-cast specimens, as confirmed by scanning electron microscopy examination. The weld wire showed an oxygen scavenging effect from the as-cast parent alloy. CONCLUSIONS: The effects of the joint gap were not significant, whereas the characteristics of the joint itself were, which displayed slightly lower strength and significantly lower ductility (and thus decreased toughness). The arc-welding of cast titanium alloy in argon atmosphere appears to be a reliable and efficient prosthodontic laboratory modality producing predictable results, although titanium casting and joining procedures must be closely controlled to minimize heat effects and oxygen contamination.

Alloys↗
PubMed2003

Effect of zirconia-modified magnesia investment on the casting of pure titanium.

Several investigations have examined magnesia-based investments for pure titanium casting. However, the thermal expansion value was insufficient at low casting temperatures and high interfacial reactivity occurred at high casting temperatures. The purpose of this investigation was to modify a magnesia-based investment by adding a heat-resistant mold material, zirconia, in different ratios to produce a more accurate titanium casting. The thermal expansion value was measured using a new precise automatic laser recording machine and pure titanium was cast using an argon casting machine. The marginal accuracy was measured using a stereomicroscope and the interfacial reactivity of the titanium was evaluated using X-ray diffraction analysis. The results indicate that adding different amounts of zirconia to a magnesia-based investment can increase its thermal expansion value and decrease the interfacial reactivity of the titanium. Maximal thermal expansion in the zirconia-modified investments significantly increased by 5-6 weight % (wt%) and peaked at 1.62% expansion. Selevest with 5 wt% zirconia had the smallest mean marginal discrepancy, 21.70 microm at 750 degrees C. Analysis of variance indicates significant differences in marginal discrepancy between zirconia-modified investments (p < 0.001). Adding zirconia can also decrease the interfacial reactivity of the titanium. The data indicated that proper amounts of zirconia (5-6 wt%) added to a magnesia-based investment can produce a more accurate and less interfacial reactive pure titanium casting.

Dental Casting Investment↗
PubMed1989

The qualitative assessment of cobalt-chromium castings for partial dentures.

Criteria for objective assessment of cobalt-chromium castings have been developed. A random sample of 21 commercial dental laboratories specialising in the production of cobalt-chromium castings was selected. Identical casts and instructions for the construction of a lower partial denture framework were sent to each of them. The resultant castings were assessed according to specific criteria relating to detailed design features. Only one laboratory produced a casting which conformed completely with the design instructions. Significant defects were found in a high proportion of castings. The range of charges was from 28 pounds to 85 pounds. The results of the qualitative assessments suggest only a very weak relationship between laboratory charges and the quality of cobalt-chromium castings. Suggestions are made for minimum standards that may be applied in clinical practice.

Chromium Alloys↗
PubMed2002

Internal porosity of cast titanium removable partial dentures: Influence of sprue direction on porosity in circumferential clasps of a clinical framework design.

STATEMENT OF PROBLEM: Although internal porosity is a potential risk factor for clasp fracture, little is known about its frequency in the clasps of titanium removable partial dentures. PURPOSE: This study investigated the influence of the direction of auxiliary sprues on porosity in the circumferential clasps of a pressure-cast titanium removable partial denture. MATERIAL AND METHODS: Wax patterns of a removable partial denture framework were made on 10 identical refractory casts of a Kennedy class II, modification 1, mandibular partially edentulous arch. For the auxiliary sprues directed to the circumferential clasps, 2 designs were used: straight and curved. Casting was performed in a 1-chamber pressure casting machine. Pore number and size were assessed on radiographs of the castings. The data were analyzed with the 2-tailed Student t test (P <.05). Randomly selected specimens were sectioned for morphologic observation of the internal surface of the pores. RESULTS: The number of pores >or=0.5 mm diameter and the total number of pores were significantly lower in the molar lingual arms of the curved sprue group than in the corresponding clasp arms of the straight sprue group (P =.03 and P =.009, respectively). No significant differences between the 2 groups were found for pores of any size in other locations. The pores had smooth internal surfaces. CONCLUSION: Within the limitations of this study, the curved sprue design produced significantly less porosity in the circumferential clasp arms of a cast titanium removable partial denture than the conventional straight design. The results suggest that internal porosity in titanium castings can be controlled through sprue design.

Dental Casting Technique↗
PubMed2001

Serial plaster casting to correct equino-varus deformity of the ankle following acquired brain injury in adults.

PURPOSE: Proposed mechanisms via which serial casting might effect increased joint range, muscle extensibility and reduced reflex excitability are outlined in this review. Support for these mechanisms stems largely from animal experimental studies. The applicability of these data to human muscle is unknown. ISSUES: Equino-varus deformity of the ankle is a common secondary complication of acquired brain injury. It results from a combination of sequelae of the brain injury and subsequent immobility, including hypertonia, reduced muscle length and increased stiffness. Some evidence exists for the efficacy of serial plaster casts in the treatment of equino-varus deformity, although most reported studies are uncontrolled and involve small numbers of subjects. Serial casting has been shown to result in decreased resistance to passive lengthening and a reduction in dynamic reflex excitability within the lengthened muscles in children with cerebral palsy. Currently documented effects of serial casting in brain injured adults are limited to changes in range of maximal passive dorsiflexion. CONCLUSION: Serial casting should be considered as an adjunct to therapy aimed at improving functional mobility. A variety of therapeutic interventions have been used to augment the effect of the casting regime. Factors that have been demonstrated to be associated with a favourable outcome from serial casting, and recommendations for future research are also discussed in this review.

Brain Injuries↗
PubMed1996

Effectiveness of ice packs in reducing skin temperature under casts.

Skin temperature lowering effects were measured after application of crushed ice packs to the surface of synthetic and plaster casts. The skin temperature of legs in synthetic casts decreased an average of 10.4 degrees C (range, 8.3 degrees-12.6 degrees) to a minimum temperature of 19.7 degrees C (range, 16.2 degrees-21.8 degrees), and the temperature of legs in plaster casts decreased an average of 11 degrees C to a minimum of 18.7 degrees C (range, 13 degrees-22.8 degrees). It took an average of 56 minutes (range, 40-80 minutes) for the legs in synthetic casts and 63.8 minutes (range, 26-116 minutes) for the legs in plaster casts to reach the minimum temperature. Cryotherapy is used clinically with the intention of lowering skin temperature and presumably decreasing the pain and swelling of a patient's injured extremity. The presence of a synthetic or a plaster cast does not eliminate the lowering effects of skin temperature when crushed ice packs are applied to the surface of the casts.

Adult↗
PubMedDate not supplied

Spica cast application in the emergency room for select pediatric femur fractures.

OBJECTIVES: This study was designed to evaluate the efficacy and safety of immediate spica casting in the emergency room (ER) and evaluate the effect of discharge from the emergency room on short- term complications. DESIGN: Retrospective review of patients treated with immediate spica casting in the ER between June 1, 1993 and July 30, 2001. SETTING: Major, pediatric, orthopaedic trauma and referral center. PATIENTS: A total of 145 pediatric femur fractures in children, younger than age 7 years, treated with immediate spica casting in the ER were reviewed to determine radiographic outcome and short-term complication rates. INTERVENTION: All patients underwent immediate spica cast placement in the ER under conscious sedation. Patients meeting specific criteria were discharged immediately from the ER. MAIN OUTCOME MEASUREMENTS: Radiographic acceptability of alignment at fracture union (angulation, shortening), loss of reduction, number of return visits to the emergency room, and clinical outcome at final follow-up. RESULTS: Average follow-up was 20 +/- 16 weeks (range, 1-9 months). Forty-eight patients (33%) were discharged from the ER. No clinical complications were noted at last follow-up. All children younger than age 2 years, and 86.5% of children ages 2 to 5 years, met acceptable malalignment parameters on final radiographs. There were 16 ER visits (11%) for cast problems. Re-reduction in the operating room was needed in 11 patients (8.9%); 6.9% of patients had a cast problem noted during follow-up visits. Only 9% of patients developed a major complication. Initial shortening was the only independent risk factor found to be associated with loss of reduction. Admission status had no significant effect on the number of ER visits or development of a complication. CONCLUSIONS: If there are no associated factors requiring admission (ie, child abuse or polytrauma), spica casting in the ER for pediatric femur fractures followed by immediate discharge can be safely performed with a low complication rate in children younger than age 6 years, nearly eliminating the need for general anesthesia.

Casts, Surgical↗
PubMed2006

A cost/utility analysis of open reduction and internal fixation versus cast immobilization for acute nondisplaced mid-waist scaphoid fractures.

BACKGROUND: Open reduction and internal fixation and cast immobilization are both acceptable treatment options for nondisplaced waist fractures of the scaphoid. The authors conducted a cost/utility analysis to weigh open reduction and internal fixation against cast immobilization in the treatment of acute nondisplaced mid-waist scaphoid fractures. METHODS: The authors used a decision-analytic model to calculate the outcomes and costs of open reduction and internal fixation and cast immobilization, assuming the societal perspective. Utilities were assessed from 50 randomly selected medical students using the time trade-off method. Outcome probabilities taken from the literature were factored into the calculation of quality-adjusted life-years associated with each treatment. The authors estimated medical costs using Medicare reimbursement rates, and costs of lost productivity were estimated by average wages obtained from the U.S. Bureau of Labor Statistics. RESULTS: Open reduction and internal fixation offers greater quality-adjusted life-years compared with casting, with an increase ranging from 0.21 quality-adjusted life-years for the 25- to 34-year age group to 0.04 quality-adjusted life-years for the > or =65-year age group. Open reduction and internal fixation is less costly than casting ($7940 versus $13,851 per patient) because of a longer period of lost productivity with casting. Open reduction and internal fixation is therefore the dominant strategy. When considering only direct costs, the incremental cost/utility ratio for open reduction and internal fixation ranges from $5438 per quality-adjusted life-year for the 25- to 34-year age group to $11,420 for the 55- to 64-year age group, and $29,850 for the > or =65-year age group. CONCLUSIONS: Compared with casting, open reduction and internal fixation is cost saving from the societal perspective ($5911 less per patient). When considering only direct costs, open reduction and internal fixation is cost-effective relative to other widely accepted interventions.

Adult↗
PubMedDate not supplied

Stress protection afforded by a cast on plate fixation of the distal forelimb in the horse in vitro.

Six forelimb specimens from three adult horses had the fetlock joint fused by application of a dorsal plate and by a screw placed in lag fashion through the metacarpus to each proximal sesamoid bone. Five specimens were instrumented on the central dorsal surface of the plate with a single rosette strain gage, and the plate of the sixth specimen was instrumented with four longitudinally oriented single-axis strain gages. The specimens were loaded axially in compression to 4,000 N in a cast (test 1), in a cast with a heel block (test 2), and uncast (test 3). The principal angle of strain in all specimens, in all tests, closely approximated the vertical axis at loads < 1,000 N. The principal angle in uncast specimens was significantly different at loads > 1,000 N than the cast specimens (P < .05). At loads > 3,000 N, the principal angle in test 3 closely approximated the horizontal axis, indicating a change from tension to compression on the dorsal surface of the plate, whereas the principal angle of the cast specimens was unchanged. Specimens in a cast (tests 1 and 2) suffered less surface deformation than did uncast specimens (test 3). Therefore, the cast changed the direction and extent of bending at the point of fixation, and thereby decreased the deformation of the plate. This effect would lead to greater fatigue life of the implant in the cast specimens compared with the uncast specimens.

Animals↗
PubMedDate not supplied

Evaluation using hoof wall strain gauges of a therapeutic shoe and a hoof cast with a heel wedge as potential supportive therapy for horses with laminitis.

OBJECTIVE: To evaluate using strain gauges, a hoof cast with heel wedge, and a therapeutic shoe with unsupported toe for their effectiveness in redistribution of load from the dorsal hoof wall. STUDY DESIGN: In vitro biomechanical study. SAMPLE POPULATION: Twenty forelimb specimens. METHODS: Rosette strain gauges were placed on the dorsal and lateral hoof wall of 20 normal shaped hooves. Limbs were loaded vertically using a tensile testing machine with a 1 Hz sinusoidally cycling load up to 3000 N during 15 seconds. Mean values of principal strain and direction at 2500 N load were calculated for 3 experimental conditions (unshod, therapeutic shoe with unsupported toe, and hoof cast with heel elevation) and tested by ANOVA (P<.05). RESULTS: Vertical limb loading in an unshod hoof leads to a biaxial compression of the dorsal wall with high longitudinal compression (epsilon2 = -1515 microm/m). Principal strain at the dorsal wall (epsilon2) was decreased by 23% with the therapeutic shoe and by 59% with the hoof cast. On the lateral hoof wall principal strain was unchanged with the shoe, but increased by 34% with the cast. CONCLUSIONS: Strain measurements indicate unloading of the dorsal hoof wall by both methods with the cast being more effective than the shoe. CLINICAL RELEVANCE: The hoof cast with wedge offers substantial unloading of the dorsal wall, but increases load on the quarter. Therefore a hoof cast would likely be most helpful in acute laminitis when palmar structures can still bear load. The therapeutic shoe offers rehabilitation and regrowth of the dorsal wall without increased load on the quarter wall.

Analysis of Variance↗
PubMed1988

Reaction of fibroblasts to various dental casting alloys.

The cytotoxicity of a series of dental casting alloys in the as-cast and polished condition was determined with cell culture techniques involving phase contrast microscopy to examine cell morphology and the succinic dehydrogenase histochemical reaction to measure any ring of inhibition of Balb/c 3T3 cellular respiration around alloys. Crown and bridge casting alloys and a nickel- and a cobalt-base alloy were biocompatible in the polished condition, but less so in the as-cast condition. The only two exceptions were casting alloys containing 50-60 wt% Cu. Porcelain-fused-to-metal alloys were biocompatible in either the as-cast or polished condition. This direct contact method appeared satisfactory for evaluating biocompatibility of dental casting alloys, especially since these materials are in contact with gingival tissues.

Alloys↗
PubMedDate not supplied

Knee motion in a long leg cast.

Five principles to reestablish static ligamentous stability are introduced, including secure, temporary, tibiofemoral fixation to protect against early postoperative stretch or disruption. The necessity for emphasizing this point is demonstrated by a cadaver study. Knee motion in and out of long leg plaster casts was carefully studied in necropsy specimens. Casts applied over minimal or no padding allowed significant varus-valgus, anterior, posterior, and rotatory motion at the knee when manipulated manually. Medial opening to valgus stress ranged from 64 to 100% after casting as compared to the amount of instability present prior to casting. Legs with normally contoured thighs were not protected against anterior instability after casting, and an average of 48% of precasting rotational instability remained after casting. We believe that these results are relevant to much knee ligament surgery. Current means for solving the problems posed by cast immobilization alone, including case examples, are discussed.

Animals↗
PubMed1981

A biomechanical study of cast-brace treatment of femoral shaft fractures.

The off-loading characteristics of the cast-braces of 30 patients with fractures of the shaft of the femur have been investigated, during axial loading, using strain-gauge transducers. These were applied at the level of the fracture, where the cast was circumferentially split, and to the hinges of the brace at the knee. They measured the load transferred between the two portions of the thigh cast, and between the thigh cast as a whole and the below-knee cast; by subtraction from the total load on the limb, the skeletal force at the fracture level and at the knee could be calculated. In all patients there was an increase in the fracture load as union progressed which was thought to be due to physiological feedback mechanism from the fracture site. The load carried by the two portions of the thigh cast and by the thigh cast as a whole was proportionately high at first and stabilised at an average of 35 per cent of body weight.

Adolescent↗
PubMed2000

The effect of the patellar tendon-bearing cast on loading.

We assessed the unloading effect of the patellar tendon-bearing (PTB) cast in five healthy volunteers using a new system for analysis of dynamic plantar pressure. We devised a method to improve the unloading effect of the PTB cast, and tested this using the same system. Our findings showed that the conventional PTB cast only achieved unloading of 30% of the body-weight and that the part of the cast on the leg had a more important role in the unloading than that which was in contact with the patellar tendon. When the depth of the free space under the foot inside the PTB cast was 1, 2 and 3 cm, the unloading effect was 60%, 80% and 98%, respectively. The unloading effect of the conventional PTB cast was disappointing at only 30% of body-weight. It was improved by producing a space between the sole of the foot and the cast, and was adjustable by altering the depth of this space.

Adult↗
PubMed2006

Vascular corrosion casting of the uteroplacental and fetoplacental vasculature in mice.

This chapter describes methods for making vascular corrosion casts of the uteroplacental and fetoplacental vasculature of the mouse placenta. A catheter placed in the ascending thoracic aorta of a pregnant mouse permits the introduction of a methyl methacrylate casting compound into the lower body vasculature, including the uterus and placenta. A fine-tipped glass cannula attached to a double-lumen catheter is used to instill the same casting compound in the fetoplacental vessels of mouse placentas. Following polymerization of the casting compound, tissue is digested off of the placental casts using 20% KOH. The washed and dried casts are then available for light or scanning electron microscopy. The methods described have been used to cast the mouse uteroplacental vasculature from 5.5-18.5 d gestation and the fetoplacental vasculature from 12.5 d gestation to term.

Animals↗
PubMed2006

A randomized, controlled trial of removable splinting versus casting for wrist buckle fractures in children.

OBJECTIVE: Wrist buckle fractures are a frequent reason for emergency department visits. Although textbooks recommend 2 to 4 weeks of immobilization in a short arm cast, management varies. Treatment with both casts and splints is common, and length of immobilization varies. The objective was to determine if children with distal radius and/or ulna buckle fractures treated with a removable splint have better physical functioning than those treated with a short arm cast for 3 weeks. METHODS: This was a randomized, controlled trial in the emergency department of an academic, tertiary care children's hospital. Participants were children 6 to 15 years of age with distal radius and/or ulna buckle fractures who were randomly assigned to treatment with a short arm cast for 3 weeks or a removable splint. Cast removal was at 3 weeks. A validated self-reported outcome tool, the Activities Scales for Kids performance version (ASKp), was used to measure physical functioning over a 4-week period. The main outcome was the ASKp score at 14 days postinjury. RESULTS: We randomly assigned 113 patients, and 87 were included in the final analysis: 42 in the splint group and 45 in the cast group. Study groups were similar in age, gender, bone fractured, and dominant hand injured. There were significant differences in ASKp score at day 14 and change in ASKp from baseline at days 14 and 20, indicating better functioning in the splint group. Splinted children had less difficulty with bathing throughout the entire study. There were no significant differences in pain between groups as measured by visual analog scale. There were no refractures. CONCLUSIONS: Children treated with removable splinting have better physical functioning and less difficulty with activities than those treated with a cast.

Adolescent↗
PubMed1997

Displaced isolated fractures of the tibial shaft treated with either a cast or intramedullary nailing. An outcome analysis of matched pairs of patients.

A study of ninety-nine patients who had a unilateral, displaced, isolated closed fracture of the tibial shaft was performed to determine the effect of the type of treatment on the clinical outcome. Forty-seven patients were managed with closed intramedullary nailing with reaming, and fifty-two were managed with closed reduction and a cast. The two groups were comparable with regard to the ages of the patients, the locations and amounts of displacement of the fractures, and the number of patients who had a history of smoking. The time to union was shorter in the patients who had been managed with intramedullary nailing than in those who had been managed with a cast (mean, eighteen compared with twenty-six weeks; p = 0.02). A non-union occurred in one patient (2 per cent) who had been managed with nailing and in five patients (10 per cent) who had been managed with a cast. There were no infections in either group. Removal of the nail was performed electively in twenty-six patients. Twenty-five patients who had been managed with nailing and twenty-five who had been managed with a cast were followed for a mean of 4.4 years. With use of the Iowa Knee Evaluation and the Ankle-Evaluation Rating System, the patients who had had nailing had mean scores of 96 points (range, 68 to 100 points) and 97 points (range, 74 to 100 points) for the knee and the ankle, respectively, compared with 89 points (range, 62 to 100 points) and 84 points (range, 62 to 100 points) for those who had been managed with a cast (p < 0.05). Administration of the Medical Outcomes Study Short Form-36 Health Survey to the twenty-five matched pairs of patients yielded scores that were significantly better after nailing than after treatment with a cast (a mean of 85 points [range, 27 to 99 points] compared with a mean of 74 points [range, 20 to 97 points]; p < 0.05). We concluded that the treatment of displaced closed fractures of the tibial shaft with closed intramedullary nailing with reaming provides functional results that are superior to those obtained with use of a cast.

Adolescent↗
PubMed2001

Percutaneous screw fixation or cast immobilization for nondisplaced scaphoid fractures.

BACKGROUND: Nondisplaced scaphoid fractures treated with prolonged cast immobilization may result in temporary joint stiffness and muscle weakness in addition to a delay in return to sports or work. Fixation of scaphoid fractures with a percutaneous cannulated screw has resulted in a shorter time to union and to return to work or sports. The purpose of this prospective, randomized study was to compare cast immobilization with percutaneous cannulated screw fixation of nondisplaced scaphoid fractures with respect to time to radiographic union and to return to work. METHODS: Twenty-five full-time military personnel with an acute nondisplaced fracture of the scaphoid waist consented to be randomized to either cast immobilization or fixation with a percutaneous cannulated Acutrak screw (Acumed, Beaverton, Oregon) for the purpose of this study. Time to fracture union, wrist motion, grip strength, and return to work as well as overall patient satisfaction at the time of a two-year follow-up were evaluated. RESULTS: Eleven patients were randomized to percutaneous cannulated screw fixation, and fourteen were randomized to cast immobilization. The average time to fracture union in the screw fixation group was seven weeks compared with twelve weeks in the cast immobilization group (p = 0.0003). The average time until the patients returned to work was eight weeks compared with fifteen weeks in the cast immobilization group (p = 0.0001). There was no significant difference in the range of motion of the wrist or in grip strength at the two-year follow-up evaluation. Overall patient satisfaction was high in both groups. CONCLUSIONS: Percutaneous cannulated screw fixation of nondisplaced scaphoid fractures resulted in faster radiographic union and return to military duty compared with cast immobilization. The specific indications for and the risks and benefits of percutaneous screw fixation of such fractures must be determined in larger randomized, prospective studies.

Adult↗