[Hard methacrylic polymers. 4. Copolymers of methyl methacrylate and hydroguinone dimethacrylate].
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Acrylic Resins↗
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[A colorimetric method for the determination of methyl methacrylate in the presence of methacrylate].
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Acrylic Resins↗
[Hygienic chemical studies on plastics (VIII). Migration test of methyl methacrylate and plastic additives from polymethyl methacrylate (author's transl)].
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Chromatography, Gas↗
Final report of the safety assessment of methacrylate ester monomers used in nail enhancement products.
Methacrylate ester monomers are used in as artificial nail builders in nail enhancement products. They undergo rapid polymerization to form a hard material on the nail that is then shaped. While Ethyl Methacrylate is the primary monomer used in nail enhancement products, other methacrylate esters are also used. This safety assessment addresses 22 other methacrylate esters reported by industry to be present in small percentages as artificial nail builders in cosmetic products. They function to speed up polymerization and/or form cross-links. Only Tetrahydrofurfuryl Methacrylate was reported to the FDA to be in current use. The polymerization rates of these methacrylate esters are within the same range as Ethyl Methacrylate. While data are not available on all of these methacrylate esters, the available data demonstrated little acute oral, dermal, or i.p. toxicity. In a 28-day inhalation study on rats, Butyl Methacrylate caused upper airway irritation; the NOAEL was 1801 mg/m3. In a 28-day oral toxicity study on rats, t-Butyl Methacrylate had a NOAEL of 20 mg/kg/day. Beagle dogs dosed with 0.2 to 2.0 g/kg/day of C12 to C18 methacrylate monomers for 13 weeks exhibited effects only in the highest dose group: weight loss, emesis, diarrhea, mucoid feces, or salivation were observed. Butyl Methacrylate (0.1 M) and Isobutyl Methacrylate (0.1 M) are mildly irritating to the rabbit eye. HEMA is corrosive when instilled in the rabbit eye, while PEG-4 Dimethacrylate and Trimethylolpropane Trimethacrylate are minimally irritating to the eye. Dermal irritation caused by methacrylates is documented in guinea pigs and rabbits. In guinea pigs, HEMA, Isopropylidenediphenyl Bisglycidyl Methacrylate, Lauryl Methacrylate, and Trimethylolpropane Trimethacrylate are strong sensitizers; Butyl Methacrylate, Cyclohexyl Methacrylate, Hexyl Methacrylate, and Urethane Methacrylate are moderate sensitizers; Hydroxypropyl Methacrylate is a weak sensitizer; and PEG-4 Dimethacrylate and Triethylene Glycol Dimethacrylate are not sensitizers. Ethylene Glycol Dimethacrylate was not a sensitizer in one guinea pig study, but was a strong sensitizer in another. There is cross-reactivity between various methacrylate esters in some sensitization tests. Inhaled Butyl Methacrylate, HEMA, Hydroxypropyl Methacrylate, and Trimethylolpropane Trimethacrylate can be developmental toxicants at high exposure levels (1000 mg/kg/day). None of the methacrylate ester monomers that were tested were shown to have any endocrine disrupting activity. These methacrylate esters are mostly non-mutagenic in bacterial test systems, but weak mutagenic responses were seen in mammalian cell test systems. Chronic dermal exposure of mice to PEG-4 Dimethacrylate (25 mg, 2 x weekly for 80 weeks) or Trimethylolpropane Trimethacrylate (25 mg, 2 x weekly for 80 weeks) did not result in increased incidence of skin or visceral tumors. The carcinogenicity of Triethylene Glycol Dimethacrylate (5, 25, or 50%) was assessed in a mouse skin painting study (50 microl for 5 days/week for 78 weeks), but was not carcinogenic at any dose level tested. The Expert Panel was concerned about the strong sensitization and crossor co-reactivity potential of the methacrylate esters reviewed in this report. However, data demonstrated the rates of polymerization of these Methacrylates were similar to that of Ethyl Methacrylate and there would be little monomer available exposure to the skin. In consideration of the animal toxicity data, the CIR Expert Panel decided that these methacrylate esters should be restricted to the nail and must not be in contact with the skin. Accordingly, these methacrylate esters are safe as used in nail enhancement products when skin contact is avoided.
Animals↗
Final report of the safety assessment of methacrylic acid.
Methacrylic Acid is an organic acid used at concentrations between 50 and 88 percent to pretreat the nail and maximize the adhesion between the nail and artificial nail extender. Methacrylic Acid is readily absorbed through mucous membranes of the lungs, the gastrointestinal tract, and the skin; and is distributed to all major tissues. Oral LD50 values for rats ranged from 277 to 2260 mg/kg; acute toxicity symptoms included severe gastric irritation, gasping, labored respiration, prostration and hematuria. In a short-term inhalation study, rats exposed to Methacrylic Acid at 1300 ppm showed nose and eye irritation and weight loss, while necropsy results and blood and urine tests were normal. Methacrylic Acid is an ocular toxicant in animals. Undiluted Methacrylic Acid is corrosive to the skin of rabbits and guinea pigs. Exposure as limited as 3 minutes can cause severe erythema and slight to moderate edema. Exposure from 15 minutes to 24 hours under occlusive patches can cause marked to severe discoloration, slight to severe subcutaneous hemorrhages, necrosis, ulcerations, severe erythema, edema and concave eschar. Methacrylic Acid was irritating and caused strong rubefaction and scab formation in a guinea pig maximization test at challenge concentrations from 10 to 100 percent. It was difficult to determine if the results were type IV hypersensitivity reactions or simple irritation. In three other studies, guinea pigs were not sensitized. Methacrylic Acid was not a reproductive/developmental toxicant in rats or mice. Methacrylic Acid was negative in Salmonella typhimurium mutagenicity tests using strains TA98, TA100, TA1535 and TA1537 both with and without metabolic activation, but was positive in a DNA-cell-binding assay. Case reports involving Methacrylic Acid often involve children. Effects from ingestion include drooling, gagging, and vomiting. Children exposed to Methacrylic Acid as a result of accidental spills caused first and second degree burns to the eyes, face, hands, arms, and chest. The Consumer Product Safety Commission has required child-resistant packaging for liquid household products containing more than 5 percent Methacrylic Acid (weight-to-volume) in a single package. Since Methacrylic Acid is an extremely corrosive chemical, a primary concern about its use as a cosmetic ingredient was the ability to limit exposure to the nail when pretreating the nail prior to application of an artificial nail extender. A videotape presentation demonstrated that a trained professional could use a small applicator brush to dab a limited volume of Methacrylic Acid only to the center of the nail, allowing the monomer liquid to diffuse down the nail without any exposure to the skin. There were no available data to demonstrate that an individual consumer could apply Methacrylic Acid and avoid inadvertent skin contact. In order to minimize any exposure to the acid, the Expert Panel concluded that nail primers containing Methacrylic Acid could be used safely by trained individuals instructed to ensure that there be no contact with the skin. The CIR Expert Panel recognized that there are no chronic inhalation toxicity data on Methacrylic Acid, but was concerned that inhalation of Methacrylic Acid could affect the respiratory tract. Since the inhalation exposure time is significantly increased in a commercial setting, the Panel was more concerned about the safety of the nail technician than the consumer. The Expert Panel concluded that the current NIOSH recommended exposure limit of 20 ppm would provide adequate protection.
Animals↗
Amended final report on the safety assessment of ethyl methacrylate.
Ethyl Methacrylate is a methacrylate ester used as a chemical additive in artificial fingernail enhancement products. These products may be applied by trained professionals or be provided directly to consumers with instructions for use. Ethyl Methacrylate readily polymerizes and rapidly reacts with multifunction methacrylates to form a highly cross-linked polymer. The oral LD(50) of Ethyl Methacrylate for rats ranged from 12.7 to 18.14 g/kg. In acute studies with rats, hemoglobinuria and respiratory tract lesions were observed. Animal studies indicate that Ethyl Methacrylate is a skin irritant and sensitizer. In some cases the results were dependent on the vehicle. Evidence of embryotoxicity and teratogenicity were observed in rats injected intraperitoneally with 0.1223 to 0.4076 ml/kg Ethyl Methacrylate. Positive evidence of mutagenicity was observed in the L5178Y mouse lymphoma cell assay, but not in two Ames tests. Case reports cite examples of individuals suffering allergic contact dermatitis from exposure to Ethyl Methacrylate and related methacrylates, and some degree of cross-reactivity appears to exist between widely used acrylates and methacrylates. Information from several clinical registries of sensitization reactions to various agents reported that Ethyl Methacrylate is a sensitizer, but not a potent one. Because Ethyl Methacrylate monomer is short-lived in the normal course of using artificial fingernail-enhancement products, the primary hazard is expected to be inadvertant skin contact. In order to avoid sensitization, it is necessary to avoid skin contact. It is recommended that fingernail-enhancement products containing Ethyl Methacrylate include directions to avoid skin contact because of the sensitizing potential. Based on the available data on the formulation of nail products containing this ingredient, it is concluded that Ethyl Methacrylate is safe as used, when application is accompanied by directions for use as above.
Abnormalities, Drug-Induced↗
Methacrylate uptake by isolated hepatocytes and perfused rat liver.
I showed recently (Int. J. Biochem. Cell Biol. 27, 1311-1316, 1995) that methacrylate formed in vivo from methyl methacrylate (a basic component of polymer used in medicine and industry) is very efficiently removed from the blood. To resolve whether the liver is responsible for methacrylate elimination from the blood, methacrylate uptake by isolated hepatocytes and by perfused liver was investigated. For comparative purposes methacrylate uptake by perfused heart was also examined. It has been found that methacrylate is eliminated efficiently both by isolated hepatocytes and by perfused liver. The whole liver eliminated more than 100-fold of this compound compared to the whole heart. If the rate of methacrylate uptake was calculated per gram of tissue, the liver was 10 times more effective than the heart. KCN (2 mM) addition inhibited methacrylate uptake both by the liver and the heart by approximately 40% at 20 min of perfusion. Pretreatment of rats with galactosamine, which causes liver damage, resulted in a significant inhibition of methacrylate uptake. The data presented in this paper suggest that the liver plays a central role in the methacrylate elimination from the blood. From the results published recently and presented in this paper one can conclude that the relatively low toxicity of orally administered methyl methacrylate is the consequence of a rapid ester hydrolysis with the subsequent elimination of methacrylate by the liver. The toxicity of methacrylate (especially towards organs other than the liver) could be increased under conditions leading to liver damage.
Animals↗
Analysis of residual monomers in dendritic methacrylate copolymers and composites by HPLC and headspace-GC/MS.
OBJECTIVES: The aim of this study was to analyze the residual monomer content of photopolymerized dendritic methacrylate copolymers and particulate filler composites. Headspace-gas chromatography/mass spectrometry (HS-GC/MS) was compared with high performance liquid chromatography (HPLC). METHODS: The resin mixtures consisted of a dendritic methacrylate monomer, methyl methacrylate and acetoacetoxyethyl methacrylate in varied proportions. In addition, one of the composites contained 1,4-butanediol dimethacrylate. Camphorquinone and 2-(N,N-dimethylamino)ethyl methacrylate were used as the light-activated initiator system. The content of residual methyl methacrylate and acetoacetoxyethyl methacrylate after 40 s photopolymerization were analyzed with HPLC and HS-GC/MS. RESULTS: The content of residual methyl methacrylate decreased and residual acetoacetoxyethyl methacrylate increased with increasing concentration of acetoacetoxyethyl methacrylate in the resin mixture. The results with both methods had the same trend. SIGNIFICANCE: The addition of acetoacetoxyethyl methacrylate enhanced the copolymerization of methyl methacrylate, but did not decrease the total residual monomer content. The HS-GC/MS method was found to be a feasible method in the analysis of low-boiling residuals in dental polymers.
Chromatography, High Pressure Liquid↗
Enzymatic synthesis of sorbitan methacrylate according to acyl donors.
Recently, sugar polymers have been considered for use as biomaterials in medical applications. These biomaterials are already used extensively in burn dressings, artificial membranes, and contact lenses. In this study, we investigated the optimum conditions under which the enzymatic synthesis of sorbitan methacrylate can be affected using Novozym 435 in t-butanol from sorbitan and several acyl donors (ethyl methacrylate, methyl methacrylate, and vinyl methacrylate). The enzymatic synthesis of sorbitan methacrylate, catalyzed by Novozym 435 in t-butanol, reached an approx 68% conversion yield at 50 g/L of 1,4-sorbitan, 5% (w/v) of enzyme content, and a 1:5 molar ratio of sorbitan to ethyl methacrylate, with a reaction time of 36 h. Using methyl methacrylate as the acyl donor, we achieved a conversion yield of approx 78% at 50 g/L of 1,4-sorbitan, 7% (w/v) of enzyme content, at a 1:5 molar ratio, with a reaction time of 36 h. Sorbitan methacrylate synthesis using vinyl methacrylate as the acyl donor was expected to result in a superior conversion yield at 3% (w/v) of enzyme content, and at a molar ratio greater than 1:2.5. Higher molar ratios of acyl donor resulted in more rapid conversion rates. Vinyl methacrylate can be applied to obtain higher yields than are realized when using ethyl methacrylate or methyl methacrylate as acyl donors in esterification reactions catalyzed by Novozym 435 in organic solvents. Enzyme recycling resulted in a drastic reduction in conversion yields.
Acylation↗
Synthesis and characterization of dextran-methacrylate hydrogels and structural study by SEM.
The objectives of this study were to develop a simple and reproducible method for the preparation of the hydrogel precursor dextran-methacrylate and to conduct a visual observation of the interior structure of the swollen dextran-methacrylate hydrogel with minimum artifacts. A dextran-methacrylate hydrogel precursor was synthesized by reacting dextran with methacrylic anhydride in the presence of triethylamine as a catalyst. The effects of reaction time, temperature, concentration, and catalyst amount were studied to obtain a wide range of degree of substitution (DS) in dextran by methacrylate. The dextran-methacrylate synthesized showed an enhanced solubility in water and common organic solvents. UV irradiation of dextran-methacrylate by a long-wave UV lamp (365 nm) generated a photocrosslinked hydrogel. This dextran-methacrylate hydrogel showed a range of swelling ratio from 67 to 227% and exhibited an increase in swelling ratio with a decrease in methacrylate substitution. The pH of the swelling media did not affect the swelling behavior of the dextran-methacrylate hydrogels at all the degrees of substitution used. Special cryofixation and cryofracturing techniques were used to prepare aqueous swollen dextran-methacrylate hydrogel samples for SEM observation of their surface and interior structures. A unique three-dimensional porous structure was observed in the swollen hydrogel but was absent in the unswollen hydrogel. Different pore sizes and morphologies between the surface and the interior of swollen hydrogels also were observed.
Biocompatible Materials↗
Swelling of poly(methyl methacrylate) resin at the repair joint.
This study investigated the thickness of a swollen layer between heat-activated and autopolymerized denture base polymer based on poly(methyl methacrylate) and autopolymerized repair acrylic resin. The repair surfaces of polymerized poly(methyl methacrylate) resin specimens (n = 5) were wet with methyl methacrylate liquid for 0, 0.5, 3, 30, or 60 minutes before the mixed repair resin was applied and polymerized to the surface of the specimen. The specimens were wet ground to a thickness of 0.15 mm, and the repair joint was examined using a light microscope. The thickness of the layer of swollen poly(methyl methacrylate) at the repair joint was measured from the micrographs. Both the type of polymer, ie, heat-activated or autopolymerized, and the wetting time of the repair surface with methyl methacrylate had a significant effect on the thickness of the swollen layer (P < .001). Prolonged wetting time of the repair surface of the autopolymerized poly(methyl methacrylate) increased the thickness of the swollen layer (r = .944, P = .000), but had less effect on the thickness of the swollen layer of heat-activated poly(methyl methacrylate) (r = .391, P = .005). This study suggests that methyl methacrylate diffuses more easily into an autopolymerized poly(methyl methacrylate) than into heat-activated poly(methyl methacrylate) during the repair of denture base polymer.
Analysis of Variance↗
Cross-reactivity patterns of contact-sensitizing methacrylates.
Methacrylates are well-known contact sensitizers with increasing frequency of contact leading to occupational skin disease. Here, we developed an animal model to facilitate studies on the sensitizing capacities and cross-reactivity patterns between four clinically most important allergens: methacrylate (MMA), 2-hydroxyethyl methacrylate (2-HEMA), 2-hydroxypropyl methacrylate (2-HPMA) and ethyleneglycol dimethacrylate (EGDMA). Inbred guinea pigs were immunized by ic injections of 300 microliters of 1.0 M methacrylate solutions in Freund's complete adjuvant into both flanks, both ears, and the neck. After 14 days open skin tests were performed with 50% MMA, 2-HEMA, or 2-HPMA or 10% EGDMA solutions in 40% DMSO in ethanol. Cross-reactivities were investigated 14 days later by skin testing with all four methacrylates. Using this newly developed protocol, strongly positive skin tests for methacrylates could be induced in almost all guinea pigs (MMA 26/26, 2-HEMA 16/18, 2-HPMA 15/16 and EGDMA 11/11). Whereas EGDMA induced only weak or infrequent cross-reactivities, 2-HEMA sensitization led to strong cross-reactions to all other methacrylates. Both MMA and 2-HPMA induced strong cross-reactivity to EGDMA but only weak to moderate reactivities to the other methacrylates. The absence of strong cross-reactions with monomethacrylates in EGDMA (dimethacrylate)-sensitized animals may be explained by the predominance of highly EGDMA-specific T-cells in these animals. In contrast, sensitization with MMA, 2-HEMA, and 2-HPMA would lead to recruitment of T-cells cross-reactive to the other monomethacrylates, according to their molecular similarities. The strong skin hypersensitivities observed for EGDMA in these latter groups are ascribed to enzymatic degradation into monomethacrylate compounds, notably 2-HEMA, at a rate sufficient to elicit cognate effector T-cells. The results of this study offer new insights in the development of methacrylate hypersensitivities and common cross-sensitization patterns in clinical practice.
Allergens↗
Exposure to volatile methacrylates in dental personnel.
Dental personnel are exposed to acrylates due to the acrylic resin-based composites and bonding agents used in fillings. It is well known that these compounds can cause contact allergy in dental personnel. However, in the 1990s, reports emerged on asthma also caused by methacrylates. The main volatile acrylates in dentistry are 2-hydroxyethyl methacrylate and methyl methacrylate. The aim of this study was to quantify the exposure to these acrylates in Swedish dental personnel. We studied the exposure to 2-hydroxyethyl methacrylate and methyl methacrylate in five randomly selected public dental clinics and at the Faculty of Odontology at Göteborg University. In total, 21 whole-day and 46 task-specific short-term (1-18 min) measurements were performed. The median 8-hour time-weighted averages were 2.5 microg/m3 (dentists) and 2.9 microg/m3 (dental nurses) for 2-hydroxyethyl methacrylate, and 0.8 microg/m3 (dentists) and 0.3 microg/m3 (dental nurses) for methyl methacrylate. The maximum short-term exposure levels were 79 microg/m3 for 2-hydroxyethyl methacrylate and 15 microg/m3 for methyl methacrylate, similar in dentists and dental nurses. The observed levels are much lower than in complete denture fabrication. We found only one previous study in dentistry and it showed similar results (though it reported short-term measurements only). Irritant effects would not be expected in healthy people at these levels. Nevertheless, occupational respiratory diseases due to methacrylates may occur in dental personnel, and improvements in the handling of these chemicals in dentistry are warranted. This includes better vials for the bonding agents and avoiding evaporation from discarded materials.
Dental Auxiliaries↗
Effects of methyl methacrylate on Ca2+ uptake of cardiac sarcoplasmic reticulum.
In isolated cardiac sarcoplasmic reticulum (SR) vesicles, methyl methacrylate (2.5-100mM) directly inhibited initial rates of Ca2+ uptake as well as the maximal uptake. Inhibition of SR Ca2+ uptake by methyl methacrylate was concentration-dependent, and the highest concentration of methyl methacrylate (100mM) almost completely inhibited the SR Ca2+ uptake. EC(50) of methyl methacrylate in percent inhibition of SR Ca2+ uptake was 16.1, 31.9, and 53.4mM at pCa 7.0, 6.6, and 6.0, respectively. At low Ca2+ concentrations (0.1-1 microM), SR vesicles treated with 20mM methyl methacrylate showed the decreased Ca2+ uptake rates. However, further increase of Ca2+ concentration to pCa 5.5 abolished the inhibitory effect of methyl methacrylate on SR Ca2+ uptake, showing no difference between the control and the methyl methacrylate-treated SR vesicles. From these results we could conclude that methyl methacrylate exerts a direct inhibition of cardiac SR Ca2+ uptake. This mechanism, at least in part, might contribute to the profound hypotension induced by methyl methacrylate. Supplementation of calcium ion appears to reduce the methyl methacrylate-induced cardiovascular disturbances efficiently.
Animals↗
NTP Toxicology and Carcinogenesis Studies of Methyl Methacrylate (CAS No. 80-62-6) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).
Toxicology and carcinogenesis studies of methyl methacrylate, a liquid chemical intermediate used in the plastics industry in the manufacture of plexiglass and other acrylic products, were conducted by exposing groups of F344/N rats and B6C3F1 mice by inhalation for 14 weeks and 2 years. In the 14-week studies, groups of 10 male and 10 female rats and mice were exposed to methyl methacrylate at concentrations of up to 5,000 ppm. All male and female rats and eight male and eight female mice exposed at 5,000 ppm died, one male and nine female rats and four male and no female mice exposed at 3,000 ppm died, and one male and three female rats and two male and one female mouse exposed at 2,000 ppm died; all rats and mice exposed at 500 or 1,000 ppm survived. Compared with the controls, the body weights of the exposed male and female rats and mice were lower. Compound-related lesions included inflammation associated with necrosis and loss of olfactory epithelium in the nasal turbinates in both male and female rats; malacia and gliosis in female rats; inflammation of the nasal turbinates and nasal epithelium metaplasia in both male and female mice; and renal cortical necrosis, renal cortical tubular degeneration, renal focal mineralization, and liver necrosis in male mice. Based on these results, 2-year inhalation toxicology and carcinogenesis studies were conducted in which groups of 50 male rats were exposed to methyl methacrylate at 0, 500, or 1,000 ppm; female rats at 0, 250, or 500 ppm; and male and female mice at 0, 500, or 1,000 ppm. In the 2-year studies, the body weights of the low dose and high dose male and female rats were within 10% of those of the controls. There was no difference in survival between the dosed male and female rats and the controls. Incidences of inflammation of the nasal cavity and degeneration of the olfactory sensory epithelium were greater in the dosed male and female rats than in the controls, with lesions seen in virtually all high dose animals. An increased incidence of mononuclear cell leukemia was observed in female rats exposed to methyl methacrylate at 500 ppm compared with the controls (control, 11/50; 250 ppm, 13/50; 500 ppm, 20/50). This increase was not significant by life table tests, the method of analysis most appropriate for this fatal neoplasm. The mean body weights of dosed male and female mice were 5%-8% lower than those of the controls at the end of the 2-year studies. However, during most of the second year of the studies, body weights of dosed male mice and high dose female mice were 10%-18% lower than those of the controls. Survival rates of the dosed and control mice were similar. Incidences of inflammation and epithelial hyperplasia of the nasal cavity and degeneration of the olfactory sensory epithelium were significantly greater in all dosed groups of male and female mice compared with those of the controls. Compound-related neoplastic lesions were not found in the dosed mice. Significant dose-related decreases were observed in the incidences of pituitary gland and preputial gland tumors in male rats, alveolar/bronchiolar adenomas or carcinomas (combined) in male mice, hepatocellular adenomas in both male and female mice, and pituitary gland adenomas or adenocarcinomas (combined) and uterine adenocarcinomas in female mice. Methyl methacrylate was not mutagenic in strains TA100, TA1535, TA97, or TA98 of Salmonella typhimurium in the presence or absence of male rat or hamster liver S9 when assayed by a preincubational protocol but gave a positive response in L5178Y/TK+/- mouse lymphoma cells in the presence or absence of male rat liver S9. In cultured Chinese hamster ovary cells, methyl methacrylate produced a reproducible, dose-related increase in the frequency of sister-chromatid exchanges, both with and without rat liver S9. A slight, dose-related increase in chromosomal aberrations was also induced in cultured Chinese hamster ovary cells in the absence of S9; in the presence of S9, an increase in the frequency of aberrations was seen only at the highest, near-lethalas seen only at the highest, near-lethal dose of 5 mg/ml. An audit of the experimental data was conducted for the 2-year carcinogenesis studies on methyl methacrylate. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year inhalation studies, there was no evidence of carcinogenicity of methyl methacrylate for male F344/N rats exposed at 500 or 1,000 ppm, for female F344/N rats exposed at 250 or 500 ppm, or for male and female B6C3F1 mice exposed at 500 or 1,000 ppm. Inhalation of methyl methacrylate was associated with inflammation of the nasal cavity and degeneration of the olfactory sensory epithelium in male and female rats and mice; epithelial hyperplasia of the nasal cavity was also observed in exposed mice. Synonyms: acrylic acid, 2-methyl, methyl ester; methacrylic acid, methyl ester; methyl a-methylacrylate; methyl methylacrylate; methyl-2-methylpropenoate; methyl-2-methyl-2-propenoate; 2-methyl-2-propenoic acid methyl ester; MME
Journal Article↗
Effect of surface-charged poly(methyl methacrylate) on the adhesion of Candida albicans.
PURPOSE: The aim of this study was to investigate the ability of a new surface-modified denture resin to reduce adhesion of Candida albicans to the denture surface. This material has a negative charge incorporated by copolymerization of methacrylic acid to methyl methacrylate. An in vitro system was designed to assess the adhesion of C. albicans to surface-charged poly(methyl methacrylate) (PMMA) surfaces. MATERIALS AND METHODS: Four experimental groups consisted of a control (pure PMMA) and 3 groups of modified PMMA (mPMMA) (95:5, 90:10, and 80:20 MMA:methacrylic acid). Four resin samples (11 x 5 mm) for each experimental group were made to enable the adhesion assay. Resin samples of varying ratios of methacrylic acid were placed in C. albicans suspensions, and the adherent cells were stained with Gram's crystal violet. The surface area of adherent C. albicans was examined for the entire sample using the computer image at a magnification of x 25. Percentage of surface area of adherent C. albicans colonies was averaged and compared between the control and each experimental group. Analysis of variance and Bonferroni's multiple-comparisons test were performed on the data. RESULTS: As the ratio of incorporated methacrylic acid to PMMA increased, the surface area of adherent C. albicans decreased. Analysis of data revealed a significant decrease in C. albicans adhesion to the resin blocks (p < 0.0001) when the methacrylic acid was present at 10% of the PMMA. There also existed a correlation between the surface area of adherent C. albicans and the contact angle measurement as the ratio of methacrylic acid changed. Surface contact angle analysis of resin surfaces revealed that as the amount of methacrylic acid increased, the surface energy of the resins increased. CONCLUSIONS: The present results support the role of electrostatic interaction in adhesion, and introduce an effective method of reducing adhesion of C. albicans to PMMA surfaces through modification of the surface charge of polymeric biomaterials.
Adhesiveness↗
Pore structure analysis of swollen dextran-methacrylate hydrogels by SEM and mercury intrusion porosimetry.
The objectives of this study were to visually examine the surface and interior morphology of a new class of biodegradable hydrogels based on dextran-methacrylate and to quantify the porous structure of these hydrogels in swollen state. Two techniques (scanning electron microscopy and mercury intrusion porosimetry) were used to analyze pore structure of dextran-methacrylate hydrogels as a function of the degree of methacrylate substitution. SEM was used to observe 3-dimensional network structure of cryofixed and fractured swollen dextran-methacrylate hydrogels. Image analysis of the SEM data revealed different pore shapes and sizes, depending on the degree of substitution and the location within the hydrogel. A higher methacrylate-substituted dextran hydrogel showed a compact and rigid pore structure, while a lower substituted hydrogel showed a delicate and fragile pore structure. Mercury intrusion porosimetry analysis of the pore structure of dextran-methacrylate hydrogels provided useful and more reliable quantitative data of pore characteristics, such as total pore area, average pore diameter, their distribution, and bulk density. The total pore area and average pore diameter of swollen dextran-methacrylate hydrogels decreased with an increase in degree of methacrylate substitution, while bulk density increased with an increase in degree of substitution.
Biocompatible Materials↗
Heterocyclic methacrylates for clinical applications. I. Mechanical properties.
The mechanical properties of a number of heterocyclic and one cyclic methacrylate have been studied for their potential in low polymerization shrinkage systems. This study included both homopolymers and room temperature polymerizing systems using poly(ethyl methacrylate) powder with a heterocyclic methacrylate monomer. The one cyclic methacrylate studied, isobornyl methacrylate, gave an extremely brittle polymer; furthermore, it would not form a dough with poly(ethyl methacrylate). The homopolymers gave Young's moduli in the range 1.38-2.19 GN/m2, i.e. lower than poly(methyl methacrylate). The moduli of poly(ethyl methacrylate)/monomer systems are theoretically predictable from the moduli of the homopolymers involved. The above materials were generally ductile and the mechanical properties indicated a useful class of materials for clinical use.
Biocompatible Materials↗