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Characterization of sintered TCP sheets with various contents of binder prepared by tape-casting technique.

OBJECTIVES: The purpose of this study was to investigate the effect of binder content on the characterization of sintered tricalcium phosphate (TCP) sheets prepared by the tape-casting technique. METHODS: Poly(acrylic acid)-based binder was added at four contents: 5, 10, 15, or 30 mass%, to a beta-TCP aqueous slurry. The TCP green sheets were fabricated with the prepared TCP slurry by the tape-casting technique, and were sintered at 1200 degrees C for 2h. The sintered TCP sheets were characterized by field-emission scanning electron microscope (FE-SEM) observation, X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectrometry. Apatite precipitation on the sintered TCP sheet surface in Hanks' balanced salt (HBS) solution at pH 7.4 was monitored over 14 days at 37 degrees C. RESULTS: A TCP green sheet with 5 mass% binder content had insufficient flexibility before sintering, and that with 30 mass% binder content had a problem in controlling the viscosity of slurry. FE-SEM observation showed that no differences in grain size existed in the various sintered TCP sheets. Measurement of XRD and FT-IR showed the presence of alpha-TCP phase in the various sintered TCP sheets, and same crystallographic structure was observed among various sintered TCP sheets. After 14 days immersion in HBS solution, the surfaces of sintered TCP sheets were completely covered with precipitated apatite crystals. SIGNIFICANCE: The binder content of 10 or 15 mass% is suitable for sintering TCP sheets. The sintered TCP sheet prepared by the tape-casting technique is a promising material as bone substitute.

Acrylic Resins↗

A novel method of applying a split cast.

Split plaster casts have been shown to be better than back slabs at accommodating increasing intracompartmental pressure due to swelling. Splitting a wet plaster cast can be time consuming and difficult both for the patient and the medical staff. We describe a novel method of applying a split plaster of Paris cast, which is safe, quick, convenient and inexpensive.

Casts, Surgical↗

Plaster cast immobilisation during air travel-analysis of current practice and aircraft-simulated experimental study.

BACKGROUND: There is an increase in aircraft transportation of patients with lower limb fractures. Current practice is variable. Our aim was to study current practice and to analyse the situation in an experimental simulated aircraft flight. METHODS: Current advice supplied by commercial airline offices in the UK was noted. Postal questionnaires were sent to Orthopaedic Consultants in the UK to obtain their current practice. Experimental aircraft travel was simulated in a decompression chamber with five medically fit volunteers with no fracture, immobilised in an above knee plaster cast. Compartment pressure and venous return was documented and the results analysed in two different positions with the leg elevated and dependant. RESULTS: Airlines do not have any formal guidelines. Orthopaedic consultants in the UK note variable advise in this situation. Experimental study in the aircraft simulation showed that two volunteers developed significant increase in compartmental pressure with the leg elevated to 90 degrees , which settled after the plaster cast was split. There was no increase in compartment pressure noted with leg dependant on the floor with 45 degrees of flexion at hip. CONCLUSION: The literature on this issue is limited. With our analysis we feel that patients can be transported with the plaster cast split with limb dependant on the floor i.e. hip flexion less than 45 degrees . Our volunteers had no fractures so direct comparison with pathological changes in acute fracture is problematical. Further studies into this problem are recommended.

Adult↗

Augmented external fixation versus percutaneous pinning and casting for unstable fractures of the distal radius--a prospective randomized trial.

PURPOSE: Many outcome studies of various surgical techniques for unstable fractures of the distal radius have been published but applicability of the results remains limited because the majority of these trials were not done in a prospective and/or randomized manner. In this study we evaluated 2 common surgical techniques used in the treatment of unstable distal radius fractures in a randomized prospective fashion with a 1-year radiographic and clinical follow-up period. Our hypothesis was that external fixation with augmentation would provide superior results compared with percutaneous pinning and casting. METHODS: Fifty patients younger than 65 years of age with unstable fractures of the distal radius were randomized into 1 of 2 surgical treatment groups: percutaneous pins with casting or augmented external fixation. All surgery was performed by 1 of 3 surgeons within 10 days of injury. Over 80% of the fractures were classified as AO-ASIF C2 or C3 and there was a similar distribution of fracture types in each group. RESULTS: The use of augmented external fixation did not improve the mean radiographic parameters of radial length, radial angulation, or volar tilt. Restoration of volar tilt of highly comminuted fractures was difficult to achieve regardless of the technique. Improved articular surface reduction was realized with the use of an external fixator but overall only 3 patients were noted to have steps or gaps greater than 2 mm. No significant differences in mean Disabilities of the Arm, Shoulder, and Hand scores, total range of motion, grip strength, or health-related quality of life were observed between the groups. All 3 patients diagnosed with sympathetic dystrophy had had external fixation. CONCLUSIONS: Although augmented external fixation represents a popular first line treatment for unstable fractures of the distal radius this study suggests that for fractures with minimal articular displacement similar clinical results can be obtained with percutaneous pinning and casting.

Adult↗

Characterisation of deep arterio-venous anastomoses within monochorionic placentae by vascular casting.

OBJECTIVE: To characterise arterio-venous anastomoses (AVA) in monochorionic (MC) placentae and determine (i) whether shared cotyledons lie beneath the co-termination of an artery from one twin and a vein to the contralateral twin and (ii) whether all AVA can be detected by visual inspection of the chorionic plate. METHODS: Vascular casts were made of 15 MC placentae. The number of typical AVAs suspected visually before digestion was compared with the number of AVAs identified after acid digestion. RESULTS: Thirty-three of 67 (49%) suspected typical AVAs were confirmed as typical after casting. There were five false positives and no false negatives. The remainder were classified as atypical AVAs, found in > or =90% of MC placentae. Type I (small vascular connections between two apparently normal cotyledons not seen before casting) and Type II (shared cotyledons arising within larger apparently normal cotyledons) atypical AVAs were found in 53% and 73% of placentae, respectively. CONCLUSIONS: Only half the shared cotyledons in MC placentae are characterised by co-termination of an artery and vein on the chorionic plate. We report the existence of deep anastomoses beneath the chorionic plate that cannot be visualised by chorionic plate inspection. These findings have implications for laser treatment of twin-twin transfusion syndrome.

Adult↗

A double casting technique to minimize distortion when constructing fixed partial dentures on implants.

The casting of extensive implant superstructures that have a good passive fit may be technically demanding. A simple, 2-stage casting technique is presented that avoids common problems associated with the casting of large superstructures. The fabrication of a 7-unit metal-ceramic screw-retained fixed partial denture supported by 5 implants is used to illustrate this technique.

Dental Abutments↗

Femoral shaft fractures in children treated by closed reduction and early spica cast with incorporated supracondylar Kirschner wires: a long-term follow-up results.

38 children between 1 and 10 years of age with femoral shaft fractures were treated by closed reduction and early spica cast with incorporated supracondylar Kirschner wires and followed up prospectively. Overrides of maximum 15 mm, medial and anterior angulations less than 15 degrees and lateral angulation up to 5 degrees were considered acceptable. Posterior angulation and malrotation were not accepted. Of the 38 children examined at a mean of 65.6 months (range, 58-80 months) after fracture, none had any residual skeletal deformity and joint stiffness. At long-term follow-up, maximal shortening was 11 mm and overgrowth was 6 mm. The only factor associated with unacceptable shortening was shortening > 15 mm at the time of spica cast application. We believe that close follow-up during the first 3 weeks after cast application is important in order to achieve an acceptable final outcome. On the other hand this method of treatment is simple, safe and effective. It dramatically decreases hospital stay and cost of treatment and allows rapid return of the patients to their family environment.

Bone Wires↗

A double cast fixed detachable prosthesis for the correction of severely angulated implants.

Unfavorable angulation of dental implants is a common complication that may make the design of the prosthetic device difficult and may compromise its function, access for oral hygiene procedures, and esthetic appearance. When the use of angulated abutments makes the prosthetic design unaceptable, the use of a double cast fixed detachable prosthodontic procedure may be required, which includes a cast substructure retained with conventional set screws to support a cast metal ceramic superstructure retained by semiprecision attachments and friction. This procedure improves access for oral hygienic procedures and offers better control over the esthetics and the function of the restoration.

Dental Casting Technique↗

Creating a buttonless casting by using preformed wax sprues.

Calculating precisely the amount of metal in a casting has major advantages over traditional methods. Eliminating guesswork permits making a casting without a button, which in turn facilitates the use of a larger percent of new metal with subsequent castings. This article gives details for calculating the amount of metal to be used.

Dental Alloys↗

Double-casting method for fixed prosthodontics with functionally generated path.

STATEMENT OF PROBLEM: The construction of precise fixed prostheses that are harmonious within the stomatognathic function has been regarded as a critical requirement for successful oral rehabilitation. However, techniques for construction have been unsuccessful in producing a prosthesis that can be inserted without intraoral occlusal adjustment. PURPOSE: In this study, a new method of constructing a precise prosthesis that requires limited occlusal adjustment at the final seating is described. MATERIAL AND METHODS: The precision of this method was compared with a conventional method. Fourteen artificial crowns were fabricated on an experimental abutment by using both double-casting and conventional methods. The distances between the cusp tips and occlusal surfaces of the abutments, which were measured on wax/resin patterns and resultant crowns, were recorded to estimate clinical error for each method. RESULTS: Error for the double-casting method was markedly less than the conventional method. This study demonstrated that a new double-casting method was precise and sufficiently reliable for clinical application.

Analysis of Variance↗

Effects of cilazapril on the retinal vessels in spontaneously hypertensive rats: corrosion cast and scanning electron microscopic study.

The effects of the long-term oral angiotensin-converting enzyme inhibitor, cilazapril, on retinal circulation in stroke-prone spontaneously hypertensive (SHR-SP) rats were assessed by scanning electron microscopy (SEM), corrosion casts and transmission electron microscopy (TEM). Two groups of 20 male SHR-SP rats were compared. One group was treated with 10 mg/kg/day of cilazapril from 4 to 40 weeks of age, and the other group received no treatment. A third group of male Wistar-Kyoto (WKY) rats served as age-matched controls. At regular intervals the rats were weighed, and their systolic blood pressure was measured. Cilazapril normalized systolic arterial pressure to 121+/-2.7 mm Hg (SD) in the treated SHR-SP rats. There was no significant difference in body weight between the two groups of SHR-SP. In the 40-week-old SHR-SP rats without treatment corrosion cast and SEM revealed hypertensive retinal vascular changes. In the 40-week-old SHR-SP rats treated with cilazapril, these changes were markedly decreased to the level seen in WKY rats. The differences in caliber of retinal capillaries between the treated SHR-SP and untreated SHR-SP rats were statistically significant (p<.0001). TEM in the cilazapril-treated SHR-SP rats revealed intact basement membranes (0.29+/-0.057 microm) of the endothelial cells and pericytes, but in the untreated SHR-SP rats the basement membrane was thickened (0.51+/-0.123 microm) (p<.0001) and the pericytes damaged. Our results show that the long-term administration of cilazapril decreased systolic arterial pressure to a nearly normal level and prevented hypertensive retinal vascular changes, probably by improving endothelial function. The effects of cilazapril on the retinal vasculature are described for the first time. SEM of corrosion casts is a valuable technique for showing the effects of some drugs on the vasculature easily, precisely and three-dimensionally.

Angiotensin-Converting Enzyme Inhibitors↗

In vitro corrosion resistance of high-palladium dental casting alloys.

OBJECTIVE: The objective of this study was to characterize the in vitro corrosion behavior of five high-palladium dental alloys in two media using a potentiodynamic polarization technique. METHODS: Potentiodynamic cyclic polarization between -1000 and +1000 mV (SCE), 12 h open-circuit potential measurement, and linear polarization were performed on cast specimens of three Pd-Cu-Ga alloys and two Pd-Ga alloys in deaerated 0.09% NaCl solution and Fusayama artificial saliva at 37 degrees C. Zero-current potential, corrosion current density, open-circuit potential, and polarization resistance were determined. The Kruskal-Wallis test and the Mann-Whitney U-test were used to analyze the numeric findings. RESULTS: The Pd-Cu-Ga and Pd-Ga alloys in both the as-cast and heat-treated conditions showed spontaneous passive behavior under electrochemical conditions similar to those in the oral environment. The Pd-Cu-Ga alloys Liberty and Spartan Plus exhibited increased activity in the Fusayama artificial saliva after the porcelain-firing heat treatment, which may have arisen from internal oxidation of casting defects. Heat-treated Freedom Plus had an unstable oxide film to form on the surface during anodic polarization and may have a limited tendency for pitting corrosion in the Fusayama artificial saliva. The two heat-treated Pd-Ga alloys remained passive in the test media. As a group, the high-palladium alloys exhibited satisfactory corrosion resistance. SIGNIFICANCE: Corrosion of high-palladium alloys in the oral environment involves a release of ions that is related to their biocompatibility. Knowledge of the in vitro corrosion behavior of these alloys may lead to better understanding of any biologically adverse effects in vivo.

Corrosion↗

Thromboprophylaxis with low-molecular-weight heparin in outpatients with plaster-cast immobilisation of the leg.

Deep-vein thrombosis is common after plaster-cast immobilisation for traumatic injury. We did a randomised prospective study of the effect of low-molecular-weight heparin on the incidence of deep-vein thrombosis in patients with minor injuries treated with plaster-cast immobilisation of the leg. A control group (n = 163) received no prophylaxis, the prophylaxis group received low-molecular-weight heparin once daily (n = 176). The incidence of deep-vein thrombosis in the prophylaxis group was 0% (one tailed p < 0.006) vs 4.3% in the control group. No severe side-effects of low-molecular-weight heparin were observed. Thromboprophylaxis with low-molecular-weight heparin once daily is effective in reducing the risk of deep-vein thrombosis in outpatients with plaster-cast immobilisation of the leg.

Adolescent↗

Term ovine placental vasculature: comparison of sea level and high altitude conditions by corrosion cast and histomorphometry.

The placental vascular architecture differs significantly at high altitude from that at sea level in the human and guinea-pig. Four sheep between 137 and 140 days of gestation, kept near sea level throughout gestation, were used as a normoxic control group for comparison of the placental vasculature with 10 other ewes, kept at high altitude (3820 m above sea level; Barcroft Laboratory, White Mountain Research Station, CA, USA). Placentomes from both groups were prepared for histology and scanning electron microscopy of vascular corrosion casts. Singular perfusion of fetal placentae, as well as combined maternal/fetal injection was performed. The influence of long-term hypoxaemia was determined by qualitative and semi-quantitative evaluation of corrosion casts and histological sections. The fetal vessel casts show a distinct difference in the arrangement of vessels of all sizes in response to long-term hypoxaemia. In the control group, stem arteries and veins are straight and parallel. In contrast, this is much less evident in the hypoxaemic group because arterioles and venules branch off the stem vessels more frequently and in an irregular manner. This leads to a capillary bed that is much more dense due to increased branching and capillary coiling. These observations are confirmed by histomorphometry. In the fetal vessels of high altitude sheep placentomes, we observed a decreased number of vascular cross sections (21.6 +/- 4.7 SEM versus 27.7 +/- 4.0 SEM; P = 0.02). However, the average luminal size per cross section (77.9 +/- 10.5 microns2 SEM versus 59.4 +/- 7.4 microns2 SEM; P = 0.004) was increased at high altitude and the percentage of lumina of the total area (5.7 +/- 0.5 SEM versus 5.3 +/- 0.3 SEM; P = 0.09) indicated a trend towards an increase. In maternal vessels of high altitude placentomes, the number of vessel cross sections (6.5 +/- 0.7 SEM versus 6.0 +/- 0.5 SEM; P = 0.2) remained unchanged, whereas the average luminal size (1108 +/- 122 microns2 SEM versus 844 +/- 77 microns2 SEM; P < 0.001) and the percentage of lumina out of the total area (20.9 +/- 1.8 SEM versus 17.5 +/- 1.7 SEM; P < 0.001) were increased. The interhaemal distance appeared to be slightly but not significantly increased at high altitude. These findings indicate that at high altitude the sheep placenta develops an increased materno-fetal absorptive surface to help guarantee substance exchange.

Altitude↗

The Inventory of Functional Status-Caregiver of a Child in a Body Cast.

The Inventory of Functional Status-Caregiver of a Child in a Body Cast (IFSCCBC), which was derived from the Roy Adaptation Model, includes subscales measuring the extent to which parental caregivers or their surrogates continue their usual household, social and community, childcare, personal care, and occupational activities while caring for a child in a body cast. Content validity was established at 90%. Internal consistency reliability ranged from 0.63 to 0.88, using item to subscale correlations. Subscale to total IFSCCBC score correlations ranged from 0.14 to 0.75. Initial construct validity testing was accomplished by examination of subscale to subscale correlations. The IFSCCBC may be used in research and clinical practice to assess the functional status of parents or their surrogates while they are caring for a child in a body cast.

Adult↗

Long-term survival estimates of cast gold inlays and onlays with their analysis of failures.

The aim of the present study was to assess the clinical behaviour of cast gold restorations with respect to define a gold control against current and future ceramic and composite restorations. The study sample included 50 patients with 303 cast gold restorations. All restorations were cemented with a non-adhesive technique. A total of 303 restorations were evaluated clinically and radiographically using modified United States Public Health Service criteria. Restorations recorded as having an A- or a B-rating were defined as successful. Of the 303 restorations, 42 were judged as failures, which resulted in a failure rate of 13.8% for a mean observation time (+/- s.d.) of 18.7 ( +/- 9.5) years. The estimated Kaplan-Meier survival rates (s.e.) were 96.1% (+/- 1.1%) at 10 years, 87.0% (+/- 2.2%) at 20 years and 73.5% (+/- 5.4%) at 30 years. In total, biological reasons were counted 25 times in comparison to 17 technical reasons for those 42 failed cast gold restorations, with 17 secondary caries (40%) as the most common biological reason and with 13 retention losses (31%) as the most common technical reason. The endodontically treated tooth was exclusively identified as a risk factor. The restoration type (inlay versus onlay) did not influence the survival rate.

Confidence Intervals↗

Botulinum toxin A versus fixed cast stretching for dynamic calf tightness in cerebral palsy.

OBJECTIVE: To compare botulinum toxin A injections with fixed plaster cast stretching in the management of cerebral palsied children with dynamic (i.e. non-fixed) calf tightness. METHODS: The settings were the Women's and Children's Hospital (WCH) and the Crippled Children's Association of South Australia (CCA), Adelaide, South Australia. Twenty children were selected by two paediatric rehabilitation specialists. A prospective, randomized, single-blind controlled study, was carried out, with 10 children in each arm. The clinicians were blinded as to the allocated interventions. The outcome measures for 6 months post intervention were clinical assessment, modified Ashworth Scale, Gross Motor Function Measure, 2 D-video ratings using a modified Physical Rating Scale and a global scoring scale and a parent satisfaction questionnaire. RESULTS AND CONCLUSION: Botulinum toxin A injections were of similar efficacy to serial fixed plaster casting in improving dynamic calf tightness in ambulant or partially ambulant children with cerebral palsy. The ease of outpatient administration, reduction of muscle tone and safety with botulinum toxin A was confirmed. Parents consistently favoured botulinum toxin A and highlighted the inconvenience of serial casting.

Botulinum Toxins, Type A↗

Clinical results of intraarticular fractures of the base of the fifth metacarpal treated by closed reduction and cast immobilization.

This retrospective study evaluated the results of closed reduction and cast immobilization for isolated intraarticular fractures of the base of the fifth metacarpal. Twenty-two of 37 such fractures were available for follow-up at an average of 43 months, and these had all healed at an average of 5 weeks without any cast complications. Twenty patients reported excellent or good results, and two reported fair or poor results. At follow-up, 13 had no arthrosis and nine had mild arthrosis of the carpometacarpal joint. However, outcome was not influenced by fracture type, the degree of subluxation or articular step off, or the presence of arthrosis. We conclude that isolated fractures of the base of the fifth metacarpal can be reliably treated with closed reduction and cast immobilization.

Adult↗