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PubMed1975

Structure-toxicity relationships of acrylic monomers.

Esters of acrylic acid, in particular methyl methacrylate, have wide applications in a number of industrial and consumer products, forming very desirable nonbreakable glass-like materials. In dentistry, the monomers are used to prepare dentures and a variety of filling and coating materials for the teeth. Surgeons utilize the monomers to prepare a cement which helps anchor prosthetic devices to bone. Special types of acrylic monomers such as the cyano derivatives have found a useful application as adhesive materials. Most of the acrylic acid esters are volatile substances and can produce various levels of toxicity if inhaled. A large number of workers thus exposed to the vapors of these esters can develop clinical symptoms and signs of toxicity. This paper will discuss the toxicity of a large number of acrylic esters, and will attempt to show structure-activity relationships where such data are available. General comments will also be made as to the potential health hazards this variety of esters may present to selected segments of the population.

Abnormalities, Drug-Induced↗
PubMed1997

Acrylic cement creeps but does not allow much subsidence of femoral stems.

It has been suggested that the endurance of cemented femoral reconstructions in total hip arthroplasty is affected by the creep of acrylic cement, but it is not known to what extent cement creeps under loading conditions in vivo, or how this affects load transfer. We have simulated the long-term creep properties of acrylic cement in finite-element models of femoral stem constructs and analysed their effects. We investigated whether subsidence rates measured in vivo could be explained by creep of acrylic cement, and if polished, unbonded, stems accommodated creep better than bonded stems. Our findings showed that polished prostheses subsided only about 50 microm as a result of cement creep. The long-term prosthetic subsidence rates caused by creep of acrylic cement are therefore very small and do not explain the excessive migration rates which have sometimes been reported. Cement creep did, however, relax cement stresses and create a more favourable stress distribution at the interfaces. These trends were found around both the bonded and unbonded stems. Our results did not confirm that polished, unbonded, stems accommodated creep better than bonded stems in terms of cement and interface stress patterns.

Acrylic Resins↗
PubMed2006

In vivo and in vitro evaluation of the efficacy of a peracetic acid-based disinfectant for decontamination of acrylic resins.

The purpose of this study was to assess the antimicrobial efficacy of a peracetic acid-based disinfectant for decontamination of heat-polymerized, chemically activated and microwave-polymerized acrylic resins. Resin plates were contaminated in vivo upon intraoral use by 10 volunteers for 7 nights and slabs were contaminated in vitro by contact with Bacillus subtilis and Bacillus stearothermophilus. The contaminated acrylic resin specimens were immersed in a 0.2% peracetic acid-based disinfectant (Sterilife; Lifemed) for 5 min or 10 min and placed in a BHI culture medium. After incubation at 37 degrees C for 48 h, bacterial growth was assessed by analyzing turbidity of the medium. For all types of acrylic resin, no turbidity of the medium was observed for any of the resin specimens immersed in the peracetic acid-based disinfectant for either 5 or 10 min. On the other hand, the media with specimens that were not immersed in the disinfectant (control) showed turbidity in 100% of the cases, indicating the presence of microorganisms in both tested conditions. In conclusion, immersion for at least 5 min in a 0.2% peracetic acid-based disinfectant promoted high-level disinfection of heat-polymerized, chemically activated and microwave-polymerized acrylic resins contaminated with either human saliva or Bacillus subtilis or Bacillus stearothermophilus.

Acrylic Resins↗
PubMed1999

Contact sensitivity to selected acrylate compounds in B6C3F1 mice: relative potency, cross reactivity, and comparison of test methods.

Given the increasing prevalence of occupational sensitization to acrylate compounds, n-butyl acrylate (BAC), ethyl acrylate (EAC), and trimethylol propane triacrylate (TMT) were recommended by the National Toxicology Program for hypersensitivity testing in female B6C3F1 mice. The objectives of these studies were to determine the irritating and sensitizing potential of these three compounds using an irritation assay, the murine Local Lymph Node Assay (LLNA), and the Mouse Ear Swelling Test (MEST). The minimal irritating concentration for TMT was determined to be 1.0%, whereas BAC and EAC demonstrated no irritation up to 30%, the highest concentration tested. TMT tested positive in the LLNA at concentrations as low as 0.1% whereas an induction concentration of 0.3% was required to elicit a positive response in the MEST. Furthermore, BAC tested negative in the MEST at induction concentrations as high as 30%, but yielded positive results in the LLNA at concentrations as low as 20%. EAC, at all concentrations tested, was negative in both the MEST and the LLNA. Cross reactivity was only seen when mice were sensitized with TMT and challenged with BAC. In these studies, the LLNA was a more sensitive indicator of the allergic potential of these three acrylates when compared to the MEST.

Acrylates↗
PubMedDate not supplied

Effect of the addition of poly(methyl methacrylate) beads on some properties of acrylic resin.

PURPOSE: There have been numerous attempts to improve the mechanical properties of acrylic resin. However, the fracture of dentures is still an unresolved problem. The potential advantage of self-reinforcement should be improved mechanical properties over the amorphous random polymer. This study investigated the addition of poly(methyl methacrylate) (PMMA) beads in a variety of percentages on a range of mechanical properties of PMMA denture base acrylic resin. MATERIALS AND METHODS: The transverse and impact strengths and hardness of acrylic resin specimens stored in water for periods of 1 week and 6 months prior to testing were investigated. RESULTS: The results showed that for specimens stored for 1 week, the addition of up to 25% beads produced a significant increase in the modulus of elasticity. Addition of 5% beads produced a slight but nonsignificant increase in the modulus of rupture, although additions of increasing percentages produced a decrease in the modulus of rupture. The impact strength was increased for 5% to 25% beads and decreased for 40% beads. The hardness showed only small changes. For specimens stored in water for 6 months, the modulus of rupture decreased with increasing percentages of beads. The addition of beads up to 10% significantly increased the modulus of elasticity. There was no significant increase in impact strength but a significant increase in hardness for 5% beads. CONCLUSION: The addition of PMMA beads to acrylic resin did not produce a substantial improvement in the mechanical properties and cannot be recommended as a method of reinforcement in its present form.

Acrylic Resins↗
PubMed2002

Neodymium: YAG capsulotomy rates after phacoemulsification with hydrophobic and hydrophilic acrylic intraocular lenses.

PURPOSE: To retrospectively evaluate the incidence of neodymium: YAG (ND:YAG) laser capsulotomies for posterior capsule opacification (PCO) seen with hydrophobic and hydrophilic acrylic intraocular lens implants 18 months after surgery. METHODS: One hundred and five eyes that had phacoemulsification with a continuous curvilinear capsulorhexis and implantation of either a hydrophobic or a hydrophilic acrylic posterior chamber IOL were evaluated in order to assess the incidence of PCO. Fifty-six eyes received a hydrophobic IOL (Acrysof-Alcon) and forty-nine eyes received a hydrophilic IOL (Galand-Visional). A standardized surgical protocol was performed by a single surgeon. All surgical complications were excluded and all patients had standardized postoperative medication and follow-up. RESULTS: With an average follow-up of 18 months in both groups, the incidence of posterior Nd:YAG laser capsulotomy for PCO was 8.9% in the hydrophobic group and 24.4% in the hydrophilic group, respectively (p = 0.03). CONCLUSION: Intraocular lenses made from hydrophobic acrylic material are associated with a significantly reduced rate of Nd:YAG laser capsulotomies as compared with intraocular lenses made from hydrophilic acrylic material.

Acrylic Resins↗
PubMedDate not supplied

The effectiveness of seven denture cleansers on tea stain removal from PMMA acrylic resin.

PURPOSE: In this study, seven denture cleansers were evaluated for their mode of action of tea stain removal from Perspex acrylic resin material. MATERIALS AND METHODS: Perspex acrylic resin specimens were stained using a combination of chlorhexidine and tea solution. The specimens were also treated with saliva to form an initial pellicle layer and facilitate the uptake of the stain. The capacity for stain removal was determined by measuring the optical density of the treated specimens by using a spectrophotometer. These were then exposed, for 5 minutes, to seven denture cleansers to demonstrate the percentage stain-removal ability of each cleanser. The same procedure was applied for roughened Perspex acrylic resin specimens. Water was used as a control in the two parts of the experiment. RESULTS: The products containing alkaline hypochlorite had the highest ability for removing stain from the acrylic resin material together with a bleaching effect. The results varied when the same denture cleansers were used on the roughened Perspex surface, and this was attributed to the presence of irregularities and porosities on the blocks. CONCLUSION: Denture cleansing agents containing hypochlorite and Boots Denture Cleaning Powder (constituents not stated by the manufacturer) exhibited the ability to remove stain from the denture base materials most effectively. Irregularities and porosities present on the denture surface played a major role in reducing the activity of denture cleaning agents and hence increased stain and plaque retention.

Acrylic Resins↗
PubMedDate not supplied

[Pathways of degradation of organic components of waste water of (meth)acrylate-producing factories to methane by communities of microorganisms of adapted and unadapted sludge].

Pathways of the degradation of the main compounds of (meth)acrylate-producing factories wastewater (methyl methacrylate, methyl and butyl acrylate, acrylate and methacrylate, acetone, isopropanol, butanol and methanol) by the anaerobic microbial consortium of mesophilic unadapted granulated sludge from the "UASB" reactor and of adapted activated sludge from the contact reactor were comparatively studied. It was shown that the degradation of fatty acids and alcohols took place in both types of sludge. Methacrylate, acrylate and acetone degradation occurred only in adapted sludge. Both types of sludge were characterized by the reversible conversion of acetone and isopropanol and by the presence of the isomeric transition of butyrate and isobutyrate too. The present results allow to suggest that the adaptation of activated sludge to substrate includes the accumulation of biomass of microorganisms capable of hydrolyze specific substrates into such general intermediates as low-molecular-weight fatty acid and alcohols further metabolized to methane and carbon dioxide.

Acrylates↗
PubMedDate not supplied

Effects of denture teeth on the dimensional accuracy of acrylic resin denture bases.

The Michigan Computer-Graphics Coordinate Measurement System was used to determine the effects of artificial denture teeth on the accuracy of acrylic resin denture bases. Two poly(methyl methacrylate) acrylic resins and two processing techniques were tested. Groups processed with denture teeth reproduced more accurate points than groups processed without denture teeth. Groups processed with a conventional heat-polymerized acrylic resin reproduced more accurate points than groups polymerized with an injection pressing type of acrylic resin.

Acrylic Resins↗
PubMedDate not supplied

Dimensional stability of acrylic resin materials after microwave sterilization.

Microwave sterilization techniques have previously been discussed in the literature, but there is need for information regarding the stability of acrylic resins subjected to these techniques. The purpose of this investigation was to measure and determine the potential influence of microwave sterilization on the dimensional stability of polymerized acrylic resin denture base materials. Uniform samples of previously heat-polymerized, autopolymerized, and visible-light-polymerized acrylic resins were measured for changes in weight and length before and after microwave exposure. All three acrylic resin materials maintained excellent stability; all materials had shrinkage values in the range of 0.02% to 0.03%. This is clinically insignificant compared to polymerization shrinkage, which averages 0.2%.

Acrylic Resins↗
PubMedDate not supplied

Metabolism and disposition of n-butyl acrylate in male Fischer rats.

Butyl acrylate (BA) is one of the major monomers used in the manufacture of polymers and resins. Because little is known regarding its metabolic fate in animals, it was of interest to study the metabolism and disposition of BA in the rat. After oral administration, butyl [2,3-14C]acrylate was rapidly absorbed and metabolized. The acrylate moiety was metabolized primarily to CO2, accounting for elimination of up to 75% of the administered radiolabel. Elimination in urine and feces accounted for approximately 10 and 2% of the dose, respectively. Initial clearance of radioactivity from the tissues was very rapid and then decreased to a negligible rate 2 hr after iv administration. Total radioactivity in the major tissues was relatively constant from 2 to 24 hr. The majority of the radioactivity in the blood at 24 hr was found to be covalently bound to the protein fraction of the red blood cell membranes. There was some evidence of a first-pass effect when BA was administered by gavage because iv administration resulted in less metabolism to CO2 and quantitative differences in urinary metabolites. The two major metabolites in urine were identified as N-acetyl-S-(2-carboxyethyl)cysteine and N-acetyl-S-(2-carboxyethyl)cysteine-S-oxide. Results of this study indicated that the major portion of a BA dose was hydrolyzed to acrylic acid, which was further metabolized to compounds available for oxidative metabolism. Radiolabeled carbons from the BA molecule were excreted as CO2 or incorporated in trace amounts into lipids, proteins, and other products of de novo synthesis. A smaller portion of the BA dose was conjugated with endogenous glutathione.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylates↗
PubMed1979

[Studies on the thinning of the upper acrylic resin complete denture with the reinforced palate. (Part 1). Thinning of the resin denture base with the standard shape (author's transl)].

The acrylic denture bases are most commonly used as compared with metallic denture bases at present. For this reason, it is due to many excellent properties, for example, simple processing, easy repair, cheapness and so on. But an inherent disadvantage is liability of an acrylic denture base to make thick so as to maintain stiffness and strength and it makes patients uncomfortable. Therefore, the purpose of this paper is to make the palatal region of the upper complete denture thin with about 0.7 mm in thickness, and to keep the same mechanical properties as the normal resin dentures using the composites materials with carbon cloth. Tensils test of the plate test-piece and uniform bending test of the upper complete denture with steel wings were respectively performed. The results obtained in this investigation are as follows: 1) The acrylic composites reinforced with carbon cloth have shown the superior mechanical properties to be compared with the acrylic resin to be generally used. 2) The thickness of the reinforced thin denture is decreased to 0.7 mm (its thickness is 60% of the normal thickness of the one), nevertheless, the stiffness and strength are increased with the using of the composite materials. 3) The region of highest surface tensile stress in the denture was on the polished surface of the palatal aspect of the denture in the area immediately behind the anteriors, but at this region, the strain of the reinforced thin denture base decreased its strain 10% in comparison with the non-reinforced normal thick one.

Acrylic Resins↗
PubMedDate not supplied

[Interaction of acrylates with the microsomal oxidation system in the rat liver].

Esters of acrylic and methacrylic acids (methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate) binding with cytochrome P-450 in rat liver microsomes, formed the spectral complexes of the first order with maximal extinction at 381-388 nm and minimal--at 416-425 nm. Dimethylaniline, used as a classical substrate of oxidation in reactions catalyzed by cytochrome P-450, inhibited the complexes formation by the mixed type. Acrylates increased the oxygen consumption and NADPH oxidation in rat liver microsomes.

Acrylates↗
PubMed1983

[Evaluation of health hazards of workers of the textile industry working in contact with latex substances on the acrylic compound base].

The paper is aimed at quantitative and qualitative determination of acrylic compounds that may occur in air at the "Lentex" Plant in Lubliniec, along with microclimate parameters measurements. The initial method was that of the Polish Standard PN-78/z-04113, which was subsequently modified. Pursuant to this standard, acrylic compounds were determined by gas chromatography with new column pack and changed parameters of gas chromatograph. The conditions of acrylic esters and acrylonitrile separation on column with LAC-1R-296 phase were considered the best and were used for quantitative and qualitative estimation. The investigations were carried out at workstations, basing on the production stage. The obtained results of identified acrylates concentrations are indicative of a very little content of those compounds in workstations air, implying that those workstations are safe in respect of chemical risk to workers. Certain deviations from mandatory standards were exhibited by almost all microclimatic parameters which might result in workers' worse general feeling.

Acrylates↗
PubMed1997

Absence of systemic in vivo genotoxicity after dermal exposure to ethyl acrylate and tripropylene glycol diacrylate in Tg.AC (v-Ha-ras) mice.

Acrylates may be polymerized to stable surface coatings (paints, lacquers, inks, etc.) by alkylation via the Michaelis-type addition reaction. Thus, acrylates have an inherent potential as electrophiles to be genotoxic, limited in their biological activity by their physicochemical properties. To evaluate their systemic genotoxicity, ethyl acrylate (EA), tripropylene glycol diacrylate (TPGDA), or Lacquer A, an ultraviolet radiation curable lacquer containing TPGDA as the active ingredient, were applied dermally to Tg.AC mice (3 times a week for 20 weeks). Peripheral blood leukocytes were evaluated for DNA damage (single-strand breaks, alkali labile sites, DNA crosslinking) at weeks 4, 8, 12, 16, and 20 by using the alkaline (pH: 13) single cell gel (SCG) assay. Peripheral blood polychromatic erythrocytes (PCE) and normochromatic erythrocytes (NCE) were evaluated for the presence of micronuclei at week 20. The extent of DNA migration in leukocytes and the frequency of micronucleated erythrocytes was not significantly altered by treatment with TPGDA when administered alone or in Lacquer A or with EA, at doses that induced cell proliferation in keratinocytes. The absence of genotoxicity in these two cell populations suggests that these acrylates are not genotoxic or that they are not absorbed systemically when applied dermally. However, a significant, dose-dependent increase in the percentage of PCE relative to the vehicle control was present in mice treated with TPGDA, while a dose-dependent, but nonsignificant, increase in the percentage of PCE was observed in mice treated with Lacquer A. This observed increase in the rate of erythropoiesis may reflect bone marrow/blood toxicity, a homeostatic mechanism in response to the treatment-induced tumor burden, and/or a hematopoietic response to epidermal keratinocyte cytokines induced by tissue injury.

Acrylates↗
PubMed2004

Influence of mixing method on the cement temperature-mixing time history and doughing time of three acrylic cements for vertebroplasty.

Acrylic cements are increasingly being used to augment osteoporotic vertebrae in a procedure called vertebroplasty. Two significant factors that may complicate the use of acrylic cements are: (a) short handling time, which may result in insufficient filling of the vertebra; and (b) exothermic setting (curing) behavior, which may result in thermal damage of the surrounding tissue. It has been previously reported that mixing the cement components under oscillation, as compared to manual mixing, increases the handling time. More specifically, it seems that oscillatory mixing slows down the cement polymerization process and, consequently, widens the time window during which cement is injectable. However, the effect of oscillatory mixing on the exothermic setting behavior of cement undergoing polymerization has not been examined. In this study, the exothermic setting behavior of three commercially available acrylic cements--Antibiotic Simplex, DP-Pour&trade, and Vertebroplastic--were examined for both manual and oscillatory mixing methods. For each combination of cement and mixing method, the parameters that were measured were the exothermic setting curve (and hence the cement setting temperature and setting time) and the cement doughing time. It was found that oscillatory mixing had no significant effect on any of these parameters. Based on the results of this study, it can be concluded that, for the tested cements, the setting process is a reaction-controlled process rather than a diffusion-controlled one. Clinically, this implies that oscillatory mixing may be used to increase the working period for acrylic cements without increasing the risk of thermal damage to surrounding tissue.

Bone Substitutes↗
PubMed2004

Evidence of octacalcium phosphate and Type-B carbonated apatites deposited on the surface of explanted acrylic hydrogel intraocular lens.

Fourier-transform infrared (FTIR) microspectroscopy combining with attenuated total reflection (ATR) microsampling technique and micro-Raman spectrophotometer were used to detect the deposited materials on the surface of acrylic hydrogel intraocular lens (IOL) with or without ocular implantation. Surface morphology and the interface of this IOL were further examined by a confocal laser scanning microscope. The brand-new IOL exhibited a very smooth, transparent and featureless surface, but the explanted IOL had an irregular cerebriform-like opaque appearance. Both FTIR/ATR and Raman microspectroscopic analyses showed the deposits on the surface of acrylic hydrogel IOL after ocular implantation to consist of octacalcium phosphate (OCP) and Type B carbonated apatites, leading to the opalescence of acrylic hydrogel IOL. Both vibrational microspectroscopic examinations also confirmed the mineralization still in progress on the surface of acrylic hydrogel IOL after ocular implantation for 2 years.

Aged↗
PubMed1997

A Study of the Adsorption of Acrylic Acid and Maleic Acid from Aqueous Solutions onto Alumina

The adsorption of acrylic acid and maleic acid on alumina was studied, and it has been found that the adsorption obeys the Langmuir isotherm. The adsorption of the acids is dependent on the pH of the solutions. For acrylic acid, the optimal pH is 4.5; for maleic acid, the optimal pH is 1.1-1.6. These pH values are close to the pKa for acrylic acid and pKa 1 for maleic acid, respectively. The maximum amount of each acid adsorbed at its optimal pH was obtained by fitting the adsorption data to the Langmuir isotherm, and the values are 727 &mgr;mol/g for acrylic acid and 525 &mgr;mol/g for maleic acid. These values are consistent with monolayer adsorption. Solid state 13 C NMR was used to investigate the nature of the adsorption. It is suggested that the adsorbed carboxylic acids are present in the undissociated form.

Journal Article↗