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PubMedDate not supplied

In vivo heat transfer capacities of autopolymerizing, heat-polymerizing, and injection-molded acrylic resins.

The aim of this pilot study was to measure the heat transfer capacities of heat-polymerizing, injection-molded, and autopolymerizing acrylic resins in vivo. Two volunteers used acrylic resin removable plates and consumed hot (69 degrees C) and cold drinks (6 degrees C). Differences between oral temperature and highest and lowest temperature readings were recorded. Temperature changes for the autopolymerizing acrylic resin were found to be significantly higher than the heat-polymerizing and injection-molded acrylic resins for both cold and hot drinks. Despite the disadvantages of autopolymerizing acrylic resins, their high heat transfer capacity may be an advantage.

Acrylic Resins↗
PubMed1990

Immediate contact hypersensitivity to acrylic acid.

A chemical worker developed acute generalized urticaria after working with acrylate compounds in a laboratory. Immediate-hypersensitivity testing to acrylic acid yielded a severe local reaction. Testing with other acrylate compounds was negative. Re-exposure in the work-place to vapors of acrylic acid resulted in generalized urticaria. With the cooperation of the employer, the patient moved to a marketing job with no contact with acrylic acid and has remained free of urticaria since.

Acrylates↗
PubMed1989

[Adherence of Candida albicans to acrylic surfaces].

The ability of Candida albicans IFO 1385 to adhere to acrylic and the partial characterization of an adhesive substance, named AS, which was isolated from the yeast, were studied in vitro. The results obtained were as follows: 1. The cells cultured in the synthetic media (YNB) containing 500 mM galactose showed a much greater tendency to adhere than did those cells cultured in the YNB containing 500 mM glucose. 2. More cells prepared by the standing cultivation adhered to acrylic than did those prepared by the stirring cultivation. 3. A large number of the adherent cells was obtained when the acrylic plates were incubated at 37 degrees C for 90 min in the cell suspension at a concentration of 1.0 x 10(7) cells/ml. The plates were observed without staining. 4. AS was isolated from the surface of C. albicans, grown on different carbon sources (50 mM glucose, 500 mM glucose and 500 mM galactose), by treatment with ultrasonication. 5. Three different kinds of AS isolated from the three carbon sources were slightly soluble in distilled water. All were similar in composition to each other, and contained 62-68% carbohydrate (as glucose) and 23-26% protein (as BSA). 6. Silica particles adhered to acrylic coated with AS and pretreatment of acrylic with AS promoted C. albicans adhesion. However, similar pretreatment inhibited subsequent Candida glabrata and Candida krusei adhesion. As to subsequent adhesion of Candida tropicalis, no significant data were obtained. 7. Adhesion assay using the silica particles, the adhesive ability of the AS was significantly reduced by treatment with trypsin or pronase E, but not with papain, alpha-amylase, dextranase or zymolyase.

Acrylic Resins↗
PubMedDate not supplied

Contact allergens in ultraviolet-cured acrylic resin systems.

Ultraviolet-cured acrylic resin systems expose the worker to an ultraviolet reactive prepolymer, multifunctional acrylate esters, and a photoinitiator system. Irritation occurs primarily with exposure to the acrylate compounds and increases with an increased number of acrylic double bonds, decreased viscosity, and the presence of hydrophilic groups. It is recommended that sensitive individuals handle these materials with nitrile gloves, but acrylics have been known to penetrate even this form of protection.

Acrylic Resins↗
PubMed1986

Surface hydrophobicity and adherence of Candida to acrylic surfaces.

The relationship between cell surface hydrophobicities and adherence capacities to acrylic surfaces was investigated with seven laboratory strains and eighteen clinical isolates of Candida species. C. albicans was less adherent to acrylic surfaces than were other species and hardly adhered to hexadecane, whereas other strains, which had a high affinity to hexadecane, were more adherent to acrylic surfaces. A correlation was observed between the adherence capacities of Candida species to acrylic surfaces and their cell hydrophobicities. When acrylic plates were coated with human whole saliva, the contact angle of the plate became smaller than that of the nontreated plate and adherence of hydrophobic strains decreased, whereas the adherence of C. albicans was not affected.

Acrylic Resins↗
PubMed1978

[Hydrogen peroxide, chloramine T and chlorhexidrine in the disinfection of acrylic resin].

The effectiveness of 3% h drogen peroxide, 5% chloramine T and 0,5% chlorhexidine gluconate solutions in disinfection of acrylic resine plates massively infected with oral flora was analysed. The acrylic resine plates used for investigations, were infected in vitro with mixed salivary flora characterized by small numbers of yeast-like fungi (1st group), or great number of these microorganisms (2nd group). Infected plates were exposed to solutions of analysed disinfectants during various time periods. After rinsing or inactivation of disinfectant residues, acrylic plates were put into bacteriological medium and incubated during 7 days period in 37 degrees C. The results of this study indicated the effectiveness of acrylic plates disinfection to be dependent on used disinfectant, time of exposition, and microorganisms present on the surface of acrylic resine. The solutions of disinfectants were less active in the cases of plates infected with material containing great numbers of yeast-like microorganisms. Among analysed disinfectants 0,5% solution of chlorhexidine was characterized by most effective and rapid activity, whereas 3% solution of hydrogen peroxide was found to be the least effective.

Acrylic Resins↗
PubMed1979

Experimental reaming of the proximal femur and acrylic cement implantation: vascular and histologic effects.

The technique of microangiography and correlated histology was used, in experiments on the proximal femora of mature mongrel dogs, to study the effects of simple medullary reaming and of reaming followed by insertion of acrylic cement. The hip joints were not disturbed. A segment of Steinmann pin, representing the stem of a hip prosthesis, was inserted into the cement as it was polymerizing. The most significant results, after reaming alone, were devascularization and apparent necrosis of large areas of the cortex of the subtrochanteric femoral diaphysis. Full recovery was observed in 6 months. However, when acrylic cement was introduced following the reaming, extensive necrosis of the inner layers of the diaphyseal cortex was still present after a year, when the observations were terminated. The presence of necrosis of bone was judged by the lack of visible osteocytes in the lacunae. After the devascularization caused by filling the diaphyseal medulla with acrylic cement, the apparently necrotic cortex was revitalized without osteoclasia. That is in contrast to the results in another study in which osteoclasia and osteoneogenesis were required to restore cortex with empty cell lacunae. This raises the question of dormant osteonecrosis in contrast to total osteonecrosis. These studies show, in thin histologic preparations, acrylic bone cement in situ in the tissues. A fibrous membrane was found at the cement-bone interface in most areas. It was thicker in the diaphysis than in the metaphysis. The physiologic effects of acrylic cement implantation are considered to be likely factors in the loosening which is observed clinically when the femoral components of hip prostheses are under protracted stress.

Acrylic Resins↗
PubMed1981

Sensitization capacity of acrylated prepolymers in ultraviolet curing inks tested in the guinea pig.

One commonly used prepolymer in ultraviolet (UV) curing inks is epoxy acrylate. Of 6 men with dermatitis contracted from UV-curing inks, 2 had positive patch test reaction to epoxy acrylate. None reacted to the chemically related bisphenol A dimethacrylate. The sensitization capacity of epoxy acrylate and bisphenol A dimethacrylate performed with the "Guinea pig maximization test" (GPM) shows epoxy acrylate to be an extreme sensitizer and bisphenol A dimethacrylate a moderate sensitizer. Cross-reaction between the two substances occurs. The epoxy resin oligomer MW 340 present in the epoxy acrylate also sensitized some animals.

Acrylates↗
PubMed1981

[Irritation and allergy to acrylates and methacrylates. - Part I: Common monoacrylates and monomethacrylates (author's transl)].

Acrylates and methacrylates are industrial chemicals with insufficiently known irritating and allergenic effects. In this paper, the simple monoacrylates and monomethacrylates are considered. Methyl acrylate is an irritant, giving a reaction in 10 out of 30 patients, when tested at 20 p. 100 in olive oil. It is also an allergen (2 out of 22 cases). Because of its irritating properties, the concentration of 2 p. 100 is proposed for allergeric investigations. Methyl methacrylate, at 20 p. 100 in olive oil, is not an irritant for humans, although we have observed a sensitization rate of about 15 p. 100 with an undiluted product. In animal studies (technic of Kligman and Magnusson), 10 p. 100 of the subjects reacted to a working concentration of 1 p. 100 in petrolatum (allergenicity degree II). A risk of sensitization due to test repetition exists, about 9 p. 100 and 15 p. 100 for methyl acrylate (20 p. 100) and undiluted methyl methacrylate, respectively. For the latter, sensitization appears around the 16 th-18th day and may be preceeded by an irritation (1 out of 3 cases). Allyl acrylate and allyl methacrylate are irritants which should be studied at a concentration of about 0,1 p. 100. A 5 p. 100 concentration in olive oil seems appropriate for studying allergies to the following monoacrylates and monomethacrylates: acrylamide and acrylonitrile, n-butyl, cyclohexyl, ethyl, ethyl-2-hexyl, ethoxy-2-ethyl, phenyl acrylates, cyclohexyl dodecyl, ethyl-2-hexyl, ethoxy-2-ethyl, methyl methacrylates.

Acrylates↗
PubMed1994

[Occupational allergy to acrylates--study of cases].

The results of patch tests with an acrylate series (29 chemical compounds) in 8 (3.4%) out of 235 patients with occupational dermatitis were presented. This group of patients consisted of four dentists--prosthodontists and four dental technicians. The following were the most frequent causes of allergy to acrylates: ethylene glycol dimethacrylate (5 positive patch tests), methyl methacrylate (4), 2-hydroxyethyl methacrylate (4), triethylene glycol dimethacrylate. Altogether there were 38 positive patch tests. Over-sensitivity to triacrylates, epoxy acrylate, N,N-methylenebis-acrylamide, urethan derivatives of acrylates and methacrylates was not observed. The most intense skin changes were observed in two prosthodontists involved as well ion general dentistry (deep fissures of digital pulp, trophic changes in nails) allergic to numerous acrylates and methacrylates (one to 14 and the other to 10).

Acrylates↗
PubMed1999

Characterization of acrylic bone cement using dynamic mechanical analysis.

Dynamic mechanical analysis (DMA) was used to characterize the properties of acrylic bone cement with the addition of tricalcium phosphate (TCP), hydroxyethyl methacrylate (HEMA), and ethylene glycol dimethacrylate (EGDMA). The glass transition temperature of acrylic bone cement is >100 degrees C; the cement has a flat modulus response near human body temperature. The height of the damping peak decreases and becomes broader with increasing TCP content. Thus, TCP is incompatibile with acrylic bone cement. When the frequency is changed from high to low, the damping peak shifts to low temperature. The shift in damping peak with frequency indicates that this relaxation is time-dependent. When acrylic bone cement contains TCP with HEMA and EGDMA, the incompatibility between acrylic bone cement and TCP can be ameliorated.

Biocompatible Materials↗
PubMed2005

Differential responses of human lens epithelial cells to intraocular lenses in vitro: hydrophobic acrylic versus PMMA or silicone discs.

BACKGROUND: The purpose of this study was to determine the influence of different materials of intraocular lenses (IOLs) on human lens epithelial cell behavior, including adhesion, migration, proliferation, apoptosis, and epithelial-mesenchymal transdifferentiation (EMT) in vitro. METHODS: Human lens epithelial cells (SRA 01/04) were grown on hydrophobic acrylic (Acrysof), polymethylmethacrylate (PMMA), and silicone IOLs. Cellular adhesion, migration, proliferation, and apoptotic assays were performed to assess cell behavior. The expression of EMT markers (fibronectin and type I collagen) produced by cells on IOLs was determined by immunoblotting and immunocytochemistry. RESULTS: Human lens epithelial cells exhibited preferred adhesion and reduced apoptosis when cultured on acrylic IOLs, in comparison to PMMA and silicone IOLs. Cells grown on acrylic lenses formed a confluent epithelial monolayer. Migration of lens epithelial cells under the acrylic lens was substantially blocked in an in vitro assay. In contrast, cells grown on PMMA and silicone lenses displayed a spindle-shaped, myofibroblast-like morphology, increased apoptosis, reduced adhesion, and enhanced production of EMT proteins such as fibronectin and type I collagen. The migration of lens epithelial cells under PMMA and silicone IOLs was substantial in the in vitro assay. CONCLUSION: This report demonstrates that hydrophobic acrylic lenses are more capsular biocompatible than PMMA and silicone lenses. The in vitro assays are reliable measurements for evaluating the responses of human lens epithelial cells to different IOL materials, and could advance our understanding of the preferential capsular opacification conferred by different IOL materials.

Apoptosis↗
PubMed1996

A new method of acrylic cranioplasty.

BACKGROUND: Previous acrylic cranioplasty techniques have relied on wire or suture fixation of the acrylic to the skull. A new methyl methacrylate cranioplasty technique, using acrylic with titanium plating, is described. METHODS: Titanium plates were bent into a "Z" shape and attached to the skull at the perimeter of the skull defect, extending into the defect. The acrylic was then poured into the defect and held in place during setting with a sheet of plastic. The plates are thereby embedded in the acrylic. RESULTS: Standard methyl methacrylate and titanium plates and screws were used to perform a new method of cranioplasty. CONCLUSIONS: A rigid, form-fitting, aesthetic construct can be easily and quickly created. This technique also offers the benefit of allowing secondary craniotomy, if necessary.

Humans↗
PubMed2004

Development of urethane acrylate composite ion-exchange membranes and their electrochemical characterization.

With the objective of introducing antifouling characteristics into interpolymer types of cation and anion exchange membranes, the surface of these membranes was coated with a 12-microm-thick urethane acrylate layer and was cured by UV radiation of wavelengths 308 and 172 nm under a complete inert atmosphere. Different urethane acrylate composite ion exchange membranes developed were characterized in NaCl solution by measuring their ion-exchange capacity, volume fraction of water, contact angle with water, membrane conductance, and membrane potential. It was found that the electrochemical transport properties of urethane acrylate composite cation-exchange membranes were increased due to resonance stabilization of the urethane group, which acts as a weak acid and dissociates as a negatively charged urethane ion and a positively charged proton. This contributes toward the net charge density of the membrane matrix responsible for enhanced selectivity and conductivity, while for urethane acrylate composite anion-exchange membranes reduction in net charge density was responsible for reduction in electrochemical transport properties. Counterion transport number, permselectivity, and counterion diffusion coefficient values for these membranes were also estimated. Experiments were also carried out in higher homologs of sodium carboxylate solutions in order to observe the fouling tendencies of these membranes. It was concluded that it is possible to obtain antifouling characteristics of ion-exchange membranes by coating and curing thin hydrophilic layers of urethane acrylate on their surfaces without sacrificing their electrochemical transport properties.

Journal Article↗
PubMed1994

The use of mouldable acrylic for restoration of the temporalis flap donor site.

Despite the wide popularity of the pedicled temporalis myofascial flap, aesthetic management of the temporalis donor site has received little attention. A technique for immediate camouflage of the temporalis flap donor site with cold-cure methyl methacrylate, either alone or in combination with residual muscle in the temporal fossa, is presented. A retrospective evaluation of this technique in 34 consecutive patients was undertaken, with particular reference to the aesthetic results and morbidity associated with the use of cold-cure acrylic for this form of reconstruction. Apart from transient postoperative swelling and neuropraxia, no major or lasting complications associated with the use of cold-cure acrylic were recorded. The aesthetics of the camouflaged temporalis donor site by acrylic alone, or when combined with part of the temporalis muscle, was judged objectively to be excellent in 25 patients, satisfactory in 3 patients, and poor in 2 patients. 4 patients who did not have acrylic reconstruction, but had part of the temporalis muscle transposed to conceal the anterior fossa depression, leaving the posterior fossa unreconstructed, were judged mostly as satisfactory. Histology of the soft tissues around an acrylic implant after nearly 2 years confirmed the good biocompatibility of this material. It is concluded that this technique is a safe and reliable method for immediate camouflaging of the temporal fossa after harvesting a temporalis muscle flap.

Adolescent↗
PubMed2005

On the origin of cis/trans stereoselectivity in intramolecular Diels-Alder reactions of substituted pentadienyl acrylates: a comprehensive density functional study.

[structures: see text] A gas-phase B3LYP/6-31+G(d) study of substituent effects on the stereochemistry of both intramolecular Diels-Alder (IMDA) reactions of 9-E- and 9-Z-substituted pentadienyl acrylates and intermolecular Diels-Alder (DA) reactions between butadiene and monosubstituted alkenes and 3-substituted acrylates is reported and involves the calculation of 230 transition structures. It was found that, although exo ("anti-Alder") addition of monosubstituted ethenes to butadiene is the norm, Alder endo selectivity is more widely predicted for 3-substituted methyl acrylate dienophiles, and this was explained in terms of secondary orbital interactions (SOIs). Whereas cis/trans selectivity for IMDA reactions involving 9-E-substituted pentadienyl acrylates generally follows the normal pattern found for the corresponding intermolecular DA reactions, the 9-Z-substituted stereoisomers generally displayed trans selectivity that was much stronger than can be attributed to effects of the isolated substituent. This is strikingly so with unsaturated electron-withdrawing substituents whose endo selectivities, displayed in intermolecular DA reactions, are reversed in the IMDA reactions of pentadienyl acrylates. The origin of this anomalous Z-effect is explained in terms of the twist-mode asynchronicity concept of Brown and Houk. These ideas are used to explain the stereochemical outcomes of IMDA reactions of other triene systems.

Journal Article↗
PubMed2003

Cytotoxicity study of homopolymers and copolymers of 2-hydroxyethyl methacrylate and some alkyl acrylates for potential use as temporary skin substitutes.

The cytotoxicities of both homopolymers and copolymers of 2-hydroxyethyl methacrylate (HEMA) and various alkyl acrylates (AA) were investigated using cell culture techniques. The particular alkyl acrylates used were methyl acrylate (MA), ethyl acrylate (EA) and butyl acrylate (BA). The AA contents of the polymers studied were in the range of 0-25% by weight. They were synthesized via bulk polymerization in the form of thin sheets of 0.5+/-0.1 mm thickness. After sterilization using ethylene oxide gas, cytotoxicity tests, including both direct and indirect contact tests, were performed using cell lines of L929 and normal human dermal fibroblasts. The results showed that P(HEMA-co-EA) with EA contents of 15-25% and P(HEMA-co-BA) with BA contents of 10-25% appeared to be non-cytotoxic and attractive for more specific cytocompatibility tests and in vivo studies with a view to their use as temporary skin substitutes.

Journal Article↗
PubMed2001

Occupational contact allergy to (meth)acrylates.

Among 13,833 patients suspected of contact dermatitis examined during the years 1978-1999, occupational contact allergy to (meth)acrylates was diagnosed in 31 patients. The 3 most common sensitizers were ethyleneglycol dimethacrylate (17 positive patch tests), 2-hydroxyethyl methacrylate (14) and triethyleneglycol dimethacrylate (6). The aim of this report was to assess the different occupations and industries responsible for occupational sensitization to (meth)acrylates. 14 of the 31 patients work in the dental sector, either as a dentist or as a student of dental technology, where (meth)acrylate-containing dental prostheses and dental composites are mainly responsible for allergy to (meth)acrylates. An increasing trend in dermatological problems related to the expansion of the use of (meth)acrylates is clearly reflected in the patient population of our dermatology department.

Adult↗