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At least 55 records · Page 3Linked to original sources
PubMed1996

Effect of provisional luting agents on polyvinyl siloxane impression material.

Eugenol-containing cements have been traditionally selected for seating provisional restorations, but incomplete polymerization of polyvinyl siloxane impression materials has been attributed to these cements. This study clinically evaluated the inhibitory effect on polymerization of a specific polyvinyl siloxane impression material with five luting agents used for provisional restorations. Three of these luting agents contained eugenol, whereas two interim cements did not contain eugenol. A total of 60 human posterior teeth were prepared for complete crowns, fitted for provisional crowns, and cemented with interim luting agents. After 2.5 weeks the provisional crowns were removed, the cement on tooth preparations was removed with an explorer, and impressions were made. The results revealed that none of the luting agents in this investigation had an inhibitory effect on polymerization of polyvinyl siloxane impression materials.

Calcium Hydroxide↗
PubMed1990

Submucosal injection of polyvinyl alcohol foam in rabbit bladder.

Submucosal injection of either polytetrafluoroethylene (Teflon) or collagen has been used in the treatment of vesicoureteral reflux. Although the methods and principles of this treatment are effective, there are concerns regarding the safety and long-term effectiveness of these substances. We present a pilot study to explore the potential of an alternate substance (polyvinyl alcohol foam) for this treatment. Polyvinyl alcohol foam (Ivalon) particles measuring 150 to 250 mu. were injected submucosally into the bladder of New Zealand white rabbits. The bladder was examined macroscopically and microscopically at 1 and 2 weeks, and 1, 2 and 3 months after the injection. The particles created a raised lesion under the mucosa that was visible to the naked eye as late as 3 months after the submucosal injection. The particles remained in a submucosal location after 3 months. At 1 week after injection there was a foreign body giant cell response to the particles. At 3 months the giant cell response persisted and the particles were surrounded by a fibrotic reaction. There was little inflammatory response otherwise. These preliminary results indicate that polyvinyl alcohol foam may be suitable for subureteral injection in the treatment of vesicoureteral reflux.

Animals↗
PubMed1992

Microparticles of polyvinyl alcohol for nasal delivery. I. Generation by spray-drying and spray-desolvation.

Spray-drying and spray-desolvation are described for the generation of polyvinyl alcohol microparticles intended for nasal administration. The spray-dried microparticles of polyvinyl alcohol were of an appropriate size distribution but consisted of hollow spheres, which made them unsuitable for nasal delivery, as rapid clearance and a varied deposition pattern would be expected. Microparticles were also produced by spraying polyvinyl alcohol (average molecular weight of 14,000) solution (12.5%, w/v) at 0.332 ml/min onto the surface of acetone (spray-desolvation). These microparticles were solid collapsed spheres with the desired size for nasal deposition (10-200 microns). This method can be applied to encapsulation of drugs that are heat labile such as peptides and proteins.

Administration, Intranasal↗
PubMed1999

The clinical, histologic, and ultrastructural presentation of polyvinyl sponge (Ivalon) breast prostheses removed for massive fluid accumulation.

The current study describes what we believe is the first report of bilateral massive seromas associated with open-cell Ivalon sponges. Additionally, the gross, histologic, and ultrastructural features consistent with previous reports of polyvinyl alcohol prostheses are presented. Despite the reported chemical inertness of polyvinyl alcohol, this material may incite a biologic response in some patients, leading to dense fibrosis and occasional foreign-body giant-cell reaction. It is postulated that the molecular breakdown products of the polyvinyl alcohol polymer may create an osmotic gradient across the periprosthetic capsule, which may lead to intracapsular fluid accumulation, as presented in this case.

Aged↗
PubMed2005

Use of polyvinyl feeding tubes and iatrogenic pharyngo-oesophageal perforation in very-low-birthweight infants.

BACKGROUND: Placement of a feeding tube may be associated with various complications, including iatrogenic pharyngo-oesophageal perforation. AIM: To determine the incidence of pharyngo-oesophageal perforation secondary to the use of polyvinyl feeding tubes in newborns weighing less than 1500 g, we conducted a retrospective study over a 3(1/2)-y period. METHODS: All the hospital files of the 371 very-low-birthweight newborns admitted were retrospectively reviewed. RESULTS: Three iatrogenic pharyngo-oesophageal perforations were observed, giving an incidence of 1:124 preterm infants. This incidence reaches values of 1:25 newborns weighing less than 750 g. Data from our cases included clinical presentation and outcome, radiological evaluation, and type of feeding tube. One infant died of sepsis, and the clinical course was compatible with mediastinitis. The other two infants were treated successfully with conservative non-surgical management. CONCLUSION: Pharyngo-oesophageal perforation in our experience exclusively involved preterm infants weighing less than 750 g after traumatic placement of a polyvinyl feeding tube. The use of a silastic feeding tube with a really soft end instead of polyvinyl catheters could probably avoid iatrogenic oesophageal perforation.

Enteral Nutrition↗
PubMed2002

An increased standardised mortality ratio for liver cancer among polyvinyl chloride workers in Taiwan.

AIMS: To determine the standardised mortality ratio (SMR) corresponding to different causes of death in workers from polyvinyl chloride polymerisation factories in Taiwan. METHODS: Retrospective cohort study of workers from six polyvinyl chloride polymerisation factories in Taiwan. A total of 3293 male workers who had been employed for at least one year during the period 1 January 1950 to 31 December 1992, and were alive on 1 January 1985 were included for analysis. Using data acquired from Taiwan's National Mortality Registry, it was found that 144 of these workers died during the period 1985-97. The follow up rate was 99% with a total number of person-years at risk of 40 557. RESULTS: SMR for all causes of death was 0.78, indicating a possible "healthy worker" effect. The SMR for liver cancer decreased with increasing age of first exposure to vinyl chloride monomer. This association was more prominent for workers who were first employed in the industry prior to 1970 (SMR 4.82). Medical records indicated that most liver cancers in this study were hepatocellular carcinoma. CONCLUSIONS: Polyvinyl chloride workers may experience a higher risk of developing liver cancer, particularly hepatocelluar carcinoma.

Adult↗
PubMed1992

In situ colonization of polyvinyl chloride, brass, and copper by Legionella pneumophila.

A sampling device (Robbins device) was used to expose brass, copper, and polyvinyl chloride plugs to potable water contaminated by Legionella pneumophila serogroup 1. Plugs were removed at approximately 1-week intervals and cultured. The colonization rates were polyvinyl chloride, 70; copper, 31; and brass, 25%. Quantitative cultures revealed that polyvinyl chloride was most heavily colonized, whereas brass was least colonized. We conclude that materials used in plumbing systems are readily colonized by Legionella and that the Robbins device provides a means for testing such materials in an in situ setting.

Bacterial Adhesion↗
PubMed1994

The incendiary characteristics of the laryngeal and reinforced laryngeal mask airway to CO2 laser strike--a comparison with two polyvinyl chloride tracheal tubes.

The incendiary characteristics of the laryngeal and reinforced laryngeal mask airway to the CO2 laser have been compared with two polyvinyl chloride tracheal tubes. Three different power densities (2.35, 4.7 and 9.8 x 10(3) watt/cm2) were used, with either oxygen or a 30% oxygen/70% nitrous oxide mixture flowing down the tube. The laryngeal mask airway (and reinforced model) was shown to be more resistant than the polyvinyl chloride tracheal tubes. The laryngeal mask tube could not be ignited at a power density of 2.25 x 10(3) watt/cm2 after five minutes, although penetration occurred in 20-30 seconds. A layer of silica ash built up at the impact site and protected the underlying tube. The laryngeal mask airway cuff was penetrated at 3 to 5 seconds. At this power density the polyvinyl chloride tube ignited in 2 to 8 seconds and the cuff was penetrated in 0.1 seconds. At the highest power density the tubes of all airways ignited within 0.2 seconds. The possibilities for improving the incendiary characteristics of the laryngeal mask airway are discussed.

Carbon Dioxide↗
PubMed2005

Microbial treatment of bis (2-ethylhexyl) phthalate in polyvinyl chloride with isolated bacteria.

In this study, we investigated the use of microbes to degrade and remove bis (2-ethylhexyl) phthalate (DEHP), a common plasticizer and a suspected endocrine disruptor, exuding from polyvinyl chloride. Four species of bacteria that utilize DEHP as their sole carbon source were isolated from garden soil, one of which, strain NK0301, was markedly more efficient than the others in degrading DEHP and was chosen for further studies. Strain NK0301 was a coryneform bacterium (1.5x1.0 microm) identified as Mycobacterium sp. from its 16S rDNA sequencing homology. It readily degraded DEHP to two major products determined by gas chromatography/mass spectrometry to be 2-ethylhexanol and 1,2-benzenedicarboxylic acid. Other phthalate esters, suspected of being endocrine disruptors, were also tested and all except two could be utilized by strain NK0301 as their sole source of carbon. When strain NK0301 was cultivated on polyvinyl chloride sheets containing DEHP as the plasticizer, it removed up to 90% of DEHP in 3 d. Following this treatment, the polyvinyl chloride sheets did not exude DEHP to artificial saliva.

Biodegradation, Environmental↗
PubMed1995

Performance of a direct, immunoseparation based LDL-cholesterol method compared to Friedewald calculation and a polyvinyl sulphate precipitation method.

The analytical performance of a direct, immunoseparation based LDL-cholesterol method (Genzyme Corporation) was evaluated on an ELAN analyser (Merck), and compared with the performance of routinely used methods (LDL-cholesterol estimated by the Friedewald equation, and LDL-cholesterol obtained after polyvinyl sulphate precipitation). Within-day coefficients of variation (CVs) were 0.79 to 2.51% for immunoseparation based LDL-cholesterol; the between-day CVs varied between 2.62 and 3.89%, i.e. within the recommended National Cholesterol Education Program (NCEP) goal of < 4%. A method comparison study, according to the National Committee for Clinical Laboratory Standards (NCCLS) EP9-P guidelines, was performed using fasting normo- and hypertriacylglycerolaemic as well as cholestatic sera. In fresh normotriacylglycerolaemic sera immunoseparation based LDL-cholesterol (y) and Friedewald LDL-cholesterol (x) values were identical as slope and intercept of the Passing & Bablok regression equation were not significantly different from one and zero, respectively (y = 1.006 x -0.107; N = 45). In contrast, immunoseparation based LDL-cholesterol (y) differed significantly from polyvinyl sulphate LDL-cholesterol (x) results (y = 0.922 x + 0.234; N = 103). Freezing normotriacylglycerolaemic sera (three weeks, -20 degrees C) resulted in a negative bias of -5.8% for the immunoseparation based LDL-cholesterol method, and in a positive bias of +5.3% for the polyvinyl sulphate method, compared to fresh specimens. Immunoseparated LDL-cholesterol was completely recovered up to at least 37.84 mmol/l serum triacylglycerols. We conclude that the immunoseparation based LDL-cholesterol method is a practical, not technically demanding technique well applicable within routine clinical laboratories.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Ethanol and polyvinyl alcohol mixture for transcatheter embolization of renal angiomyolipoma.

OBJECTIVE: The purpose of this study was to assess the immediate and midterm effects of embolization of the angiogenic component of renal angiomyolipoma in which a mixture of ethanol and polyvinyl alcohol is used as a permanent obliterator. MATERIALS AND METHODS: Seventeen patients with 18 renal angiomyolipomas (size range, 5.5-20 cm; mean size, 10 cm) were treated with transcatheter embolization over an 8-year period. Embolization was performed with a mixture of 96% ethanol and polyvinyl alcohol particles. Follow-up with CT (mean follow-up period, 22.4 months) and one (mean, 14 months) or two (mean, 27 months) angiographic examinations were conducted to evaluate changes in the size of the tumor and to look for recurrence of the angiogenic component. RESULTS: All initial angiograms showed the characteristic tortuous, hypervascular, and aneurysm-forming angiogenic component. Immediate complete obliteration was achieved in 17 tumors (94.4% technical success rate). There was one partial technical failure. Mean tumor size was reduced to 7.6 cm (mean size reduction, 24%). Fourteen patients with 15 tumors underwent one angiographic follow-up examination (mean time after treatment, 14 months), and four patients underwent two angiographic follow-up examinations (mean time after treatment, 27 months). Reduction of the angiogenic component occurred in 10 (66.6%) of the tumors and complete obliteration in five (33.3%) of the tumors. No retroperitoneal hemorrhage or tumor growth was seen during the follow-up period. No complications were encountered. CONCLUSION: We found a mixture of ethanol and polyvinyl alcohol an efficient embolizing agent with a sustained midterm effect in the management of renal angiomyolipoma. Repeated embolization was needed in tumors with a large angiogenic component. Tumor shrinkage after embolization was minimal.

Adult↗
PubMed1992

Acute lower gastrointestinal hemorrhage: treatment by superselective embolization with polyvinyl alcohol particles.

OBJECTIVE: The major risk of transcatheter embolotherapy for acute hemorrhage in the lower gastrointestinal tract is irreversible intestinal ischemia. The authors studied the efficacy and safety of superselective transcatheter embolization with polyvinyl alcohol particles in arresting acute hemorrhage in the lower gastrointestinal tract. SUBJECTS AND METHODS: All patients with clinical or scintigraphic evidence of acute hemorrhage in the lower gastrointestinal tract were considered for superselective embolization. The nine patients with angiograms that showed active hemorrhage in the lower gastrointestinal tract underwent the procedure. Superselective embolization was done through a 3-French catheter and was accomplished by using 100- to 590-microns polyvinyl alcohol particles. The segments of the intestinal tracts involved in the embolizations were examined for the presence of ischemia by endoscopy (n = 7) or histologic evaluation of a surgical specimen (n = 2) 2-44 days (mean, 11 days) after embolization or by clinical evaluation (n = 1). RESULTS: The lesions treated by this method were located in the colon (n = 8) and jejunum (n = 1). Immediate hemostasis was achieved in every case. Three patients had recurrent lower gastrointestinal hemorrhage 1-24 days (mean, 9 days) after initial embolization. Two of these patients had surgery, while one had a successful second embolization. Two asymptomatic patients were found endoscopically to have small areas of ischemia involving only the mucosa. Only one patient was shown to have severe mucosal ischemia; this involved the colon in a distribution that suggested it was not caused by the embolization. CONCLUSION: Ten superselective embolization procedures that used polyvinyl alcohol particles successfully controlled hemorrhage in the lower gastrointestinal tract in nine patients. In no case was intestinal infarction induced by the procedure, and only two endoscopically proved cases of asymptomatic mucosal ischemia occurred.

Acute Disease↗
PubMedDate not supplied

Scanning electron microscopy of hydroxylated polyvinyl acetal and conventional gauze strip nasal packing materials.

The application of nasal packing is one of the most commonly performed procedures in rhinology. Various materials have been used as nasal packing, including conventional gauze strips and hydroxylated polyvinyl acetal. Complications related to nasal packing may cause problems that lead to increased morbidity. Among those complications, infectious ones range from localized infection in the nasal cavity to toxic shock syndrome. The purpose of this study was to evaluate conventional gauze strips and hydroxylated polyvinyl acetal nasal packing materials by scanning electron microscopy, to reveal their surface characteristics that would promote or prevent the development of infectious complications. The two types of materials were examined before and after application into the nasal cavity. Scanning electron microscopy demonstrated that hydroxylated polyvinyl acetal material had a smooth surface, whereas conventional gauze strips had an irregular surface with fibers projecting, thus increasing the surface area for bacterial adherence and allowing possible evasion of bacteria from the elements of the immune system within this fibrillar structure.

Bandages↗
PubMed2006

Intrinsically radiopaque iodine-containing polyvinyl alcohol as a liquid embolic agent: evaluation in experimental wide-necked aneurysms.

OBJECT: To evaluate iodine-containing polyvinyl alcohol (I-PVA) as a precipitating liquid embolic agent, implant characteristics--including radiopacity, setting behavior, and biocompatibility--were studied in an aneurysm model in swine. METHODS: Twelve broad-based carotid artery (CA) sidewall aneurysms were surgically constructed in six pigs. Iodine-containing polyvinyl alcohol dissolved in dimethyl sulfoxide (DMSO) was injected during temporary balloon occlusion bridging the aneurysm neck. Control angiography as well as multidetector row computerized tomography (CT) angiography was performed after 4 weeks. Harvested aneurysms were investigated histopathologically and by 3-tesla high-field magnetic resonance (MR) imaging. The mean degree of aneurysm occlusion achieved was 96%. In two aneurysms a minimal protrusion of I-PVA into the CA lumen was observed. During one embolization, leakage of the liquid embolic agent due to DMSO-induced damage of the microcatheter resulted in CA occlusion. Aneurysms embolized with I-PVA could be discriminated clearly from the parent artery on CT angiograms because there was no beam-hardening artifact. High-field MR imaging allowed a detailed depiction of the liquid embolic distribution within the aneurysm. Histologically, a mild to moderate inflammatory response was found in successfully embolized aneurysms, and the polymer mass was frequently covered by a membrane of fibroblasts and endothelial cells. CONCLUSIONS: Iodine-containing polyvinyl alcohol is a ready-to-use liquid embolic agent clearly visible under fluoroscopy; additives are not required. The setting behavior allows for controlled delivery in aneurysm cavities. Histological studies performed 4 weeks after embolization revealed no sign of toxic tissue response to the liquid embolic agent. Overall, I-PVA exhibits interesting implant characteristics in that radiopaque admixtures are not necessary, thus allowing for artifact-free evaluation of treated aneurysms by using CT and MR angiography.

Aneurysm↗
PubMed2002

[Identification of unknown substances in polyvinyl chloride gloves containing non-phthalate plasticizers].

The use of polyvinyl chloride gloves containing di(2-ethylhexyl) phthalate for food contact applications is restricted. In their place, polyvinyl chloride gloves containing non-phthalate plasticizers (PVC-NP) have been introduced. They contained unknown substances, so they were studied by GC/MS, HR-MS and NMR. The chemical structures of the unknown substances were confirmed to be diethylene glycol dibenzoate, triethylene glycol dibenzoate, dipropylene glycol dibenzoate, and alkylsulfonic acid phenyl ester, which are plasticizers. Including di-isononyl adipate, the contents of the plasticizers were 37.5-48.9% in the PVC-NP gloves, and their migration levels were 1,010-1,390 ppm into n-heptane. These are very high levels. These plasticizers are not widely used for food contact polyvinyl chloride throughout the world, and they have also not been registered as self-standards by Japanese manufacturers. Careful consideration will be necessary for the selection of a suitable plasticizer substitute.

Gas Chromatography-Mass Spectrometry↗
PubMed1978

Effect of addition of inorganic acids or alkalis on gelation of polyvinyl alcohol aqueous solution by gamma-ray irradiation.--Color development with iodine--.

Below the critical concentration of polyvinyl alcohol, the effect of inorganic acids or alkalis on gelation of polyvinyl alcohol aqueous solution was investigated by color development with iodine after gamma-ray irradiation. The absorbances of the polyvinyl alcohol-iodine complex decreased remarkably in the presence of nitric or perchloric acid. These acids decompose and form oxygen or hydrogen peroxide which oxidize the polymer and leads to a fading of the color. On addition of sulfuric, phosphoric and hydrochloric acids, the absorbances decrease in the order that agrees with that of the acidity of these acids at the same molarity. In the alkaline solution the absorbances decrease by the addition of sodium hydroxide and aqueous ammonia in the order that agrees with that of the basicity of these alkalis. These results indicate that the gel formation is caused by the radiolysis of water. As a result of chemical analysis, these additives are considered not to be attached to the polymer.

Acids↗
PubMed2000

Effect of 3 medicaments on the dimensional accuracy and surface detail reproduction of polyvinyl siloxane impressions.

OBJECTIVE: The purpose of this study was to determine the effect of retraction cord medicaments (aluminum chloride, ferric sulfate, and ferric subsulfate/ferric sulfate) on the dimensional accuracy and surface detail reproduction of polyvinyl siloxane impressions. METHOD AND MATERIALS: Polyvinyl siloxane impressions were made of standardized metal dies (American Dental Association [ADA] specification No. 19) treated with 1 of the 3 retraction cord medicaments. Dimensional accuracy was evaluated by comparing the average length of a line in the impressions to the standard die. Surface detail reproduction was evaluated by viewing the impressions under low-angle illumination at x10 magnification. Reproduction was considered satisfactory if 2 of 3 horizontal lines were reproduced continuously. The dies were also evaluated under the microscope before the impression was made. RESULTS: The medicaments did not significantly effect the dimensional accuracy; mean shrinkage was within ADA guidelines in the treatment groups. All of the medicaments had an adverse effect on surface detail reproduction. These effects were statistically significant compared to the untreated control. CONCLUSION: Although the changes in dimensional accuracy were within ADA guidelines, the surface detail reproduction was modified such that the impression would be considered clinically unacceptable. For optimal results, care must taken to remove all traces of these retraction cord medicaments prior to recording of a polyvinyl siloxane impression.

Aluminum Chloride↗
PubMed2002

[Research on the synthesis and spectroscopy of the copolymer of polyvinyl alcohol and amino acid].

In this paper, a series of new polymers with grafted amino acids were synthesized. The purpose of the research is to develop a kind of polymer drugs with grafted amino acids for the treatment of some patients. The preparations of polyvinyl alcohol and amino acid were described by using inorganic acid as catalyst. The reaction methods were investigated in order to find the optimal conditions for the highest yield and purity. The copolymers were analysed and characterized by IR and 1HNMR. The result indicated that the reaction products were what we needed and the yield of the polymer of polyvinyl alcohol and glycine was higher than that of polyvinyl alcohol and alanine.

Alanine↗