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PubMed1988

Alkaline and acid phosphatase demonstration in human bone and cartilage: effects of fixation interval and methacrylate embedments.

Human bone and cartilage specimens were evaluated for acid and alkaline phosphatase localization following varying fixation periods for fresh or frozen tissue. Formalin fixations of up to 183 hr were followed by embedment in methyl methacrylate; frozen tissue was examined either without fixation or following fixation for up to 1 hr and subsequent glycol or methyl methacrylate embedding. The humeral epiphysis of a young patient with osteogenic sarcoma showed optimum acid and alkaline phosphatase localization following fixation for periods up to 15 hr and embedding in methyl methacrylate. Frozen costochondral junction from a newborn with osteogenesis imperfecta type II showed optimum acid and alkaline phosphatase localization following 30 min fixation in formalin and embedding in methyl methacrylate or after 5 min fixation and embedding in glycol methacrylate.

Acid Phosphatase↗
PubMed1989

[Adhesion of dental resin to tooth structure--syntheses and adhesion to tooth structure of various aliphatic methacrylates with a carboxylic group].

Twelve aliphatic methacrylates with a carboxylic group [succinate (2 MES, 5 MPeS and 10 MDS), methylsuccinate (2 MEMS, 5 MPeMS and 10 MDMS), maleate (2 MEM, 5 MPeM and 10 MDM) and citraconate (2 MEC, 5 MPeC and 10 MDC)] were synthesized by the addition of four dicarboxylic acid anhydrides to each of three different alkylene chain length hydroxy methacrylates to investigate the relationship between the methacrylate structure and its bonding to tooth. The bond strength of methacrylates to polished tooth surface decreased with increasing alkylene chain lengths under dry conditions, but water immersion reduced this change. The bond strength of succinate and maleate to polished tooth surface was higher than that of methylsuccinate and citraconate under dry conditions. All methacrylates showed high bond strength to etched enamel, with maleate showing the highest bond strength. On the other hand, the bond strength of 2 MEM and 5 MPeM to etched dentin was markedly high, and about 5 microns thick resin reinforced dentin at the interface between etched dentin and resin (2 MEM or 5 MPeM) was observed by SEM and EPMA analysis.

Adhesiveness↗
PubMed1989

Mortality patterns among men exposed to methyl methacrylate.

A cohort of 2,671 men, 1561 of whom were exposed to methyl methacrylate, was observed from 1951 to 1983 for mortality. This cohort consisted of men from two plants. This study utilizes detailed exposure estimates and smoking status to evaluate mortality patterns. We find no statistically significant excess all-cause or cause-specific mortality. Analysis of dose of methyl methacrylate with several cancer sites showed no trend. Men exposed to high levels of methyl methacrylate had cancer rates similar to those for men not exposed in the workplace, as well as for other men in the US population. An earlier epidemiology study reported a significant excess of colorectal cancer among persons exposed to several substances including methyl methacrylate. Our study results and results from animal studies do not support the hypothesis that methyl methacrylate is a human carcinogen.

Adult↗
PubMedDate not supplied

Impact strength of a modified continuous glass fiber--poly(methyl methacrylate).

The effect of fiber reinforcement of autopolymerizing poly(methyl methacrylate) was investigated. The impact strength of continuous E-glass fiber-poly(methyl methacrylate) composite was determined. Rectangular test specimens (n = 10 per group) were modified by incorporating an additional fiber reinforcement of untreated E-glass fibers, silanized E-glass fibers, or aramid fibers in the test specimens. Controls were either unreinforced or reinforced from the middle of the test specimen only. The impact strength of the specimens was measured by using a charpy-type pendulum impact tester after the specimens had been stored in water at 37 degrees C for 4 weeks. After the impact strength test, the length of the delamination of poly(methyl methacrylate) from the fibers was measured and plotted to the impact strength of the test specimens by using a linear regression model. The impact strength of unreinforced autopolymerizing poly(methyl methacrylate) was 7.8 kl/m2, while incorporation of glass fiber reinforcement with a fiber concentration of 12.4 wt% increased the impact strength to 74.7 kl/m2 (P = .000). The additional fiber reinforcement of the test specimen did not affect the impact strength (P = .363). Delamination negatively correlated with the impact strength of the test specimens (r = -.72, P = .000). The results of this study suggest that glass fiber reinforcement enhanced the impact strength of autopolymerizing poly(methyl methacrylate), while the use of additional fiber reinforcement made of aramid or glass fibers in the test specimens did not have an effect on the impact strength.

Analysis of Variance↗
PubMed2005

Properties of eight methacrylated beta-cyclodextrin composite formulations.

OBJECTIVES: Methacrylated beta-cyclodextrins (MCDs) are novel candidate dental monomers if all or some of the hydroxyl groups of beta-cyclodextrin are substituted with methacrylate groups. The main objective of this study was to evaluate mechanical properties of a number of composite formulations having MCDs as novel dental comonomers. The properties determined were flexural strength (FS), volumetric shrinkage (VS), and degree of conversion (DC). METHODS: A mass fraction of 50% of MCD monomers was mixed with a mass fraction of 50% each of a series of dimethacrylate or monomethacrylate diluent comonomers to produce consistent formulations of a workable viscosity. For comparison a resin mixture of a mass fraction of 50% Bis-GMA and a mass fraction of 50% triethyleneglycol dimethacrylate (a typical dental resin mixture) was also studied. The mixtures were activated with camphorquinone and ethyl 4-dimethylamino benzoate. One part by mass of each activated resin formulation was mixed with three parts by mass of glass filler. Samples for the FS tests were prepared in (2 x 2 x 25) mm3 molds by light-curing the composites for 2 min on each side. The cured samples were immersed in 37 degrees C water for 24 h, and FS was measured with an Instron machine at a crosshead speed of 0.5 mm/min. VS was measured by a computer-controlled mercury dilatometer. DC was measured by near-infrared spectroscopy. RESULTS: The properties of the MCD-based composites depended on the kind of diluent used. With these MCD monomers, diluents of triethyleneglycol dimethacrylate, 1,10-decamethylenediol dimethacrylate, or benzyl methacrylate yielded the best composite properties. SIGNIFICANCE: Although not yet fully optimized, MCD-based composite formulations containing triethyleneglycol dimethacrylate, 1,10-decamethylenediol dimethacrylate, or benzyl methacrylate yielded flexural strength and volumetric shrinkage values were comparable to those of the Bis-GMA/triethyleneglycol dimethacrylate controls. These findings lend support for further development and evaluations of polymerizable cyclodextrin derivatives for use in dental materials.

Analysis of Variance↗
PubMed1998

Use of 2-isocyanatoethyl methacrylate and iron (II) perchlorate for bonding tri-n-butylborane-initiated luting agents to dentin.

The present study investigated the effect of 2-isocyanatoethyl methacrylate (IEM) and iron (II) perchlorate on dentin adhesion. Four primers were evaluated, consisting of aqueous 2-hydroxyethyl methacrylate (HEMA) solutions containing 5, 10, 20 or 50 micromol/g iron (II) perchlorate. Five luting agents were prepared with methyl methacrylate (MMA), poly(methyl methacrylate) (PMMA), tri-n-butylborane (TBB) initiator and IEM. The concentrations of IEM in the luting agents were 0.2, 0.4, 0.8, 2.0 and 4.0 wt%. Extracted bovine teeth were ground to expose the dentin, etched with an aqueous solution of 10 wt% phosphoric acid, primed, and then bonded with stainless-steel rods; tensile bond strengths were determined after 1 d immersion in water. The highest bond strength (20.7 MPa) was recorded for the group using 10 micromol/g iron (II) perchlorate and 2.0 wt% IEM. The use of IEM was effective in decreasing the optimal concentration of iron (II) perchlorate, and this may contribute to the color stability of iron-containing pretreatment agents.

Acid Etching, Dental↗
PubMed1997

Estimation of monomer content in polymethyl methacrylate contact lens materials by Raman spectroscopy.

Polymethyl methacrylate is the most commonly used contact lens material due to its excellent optical properties. However the presence of residual monomer in the structure alters its transparency as well as its biocompatibility, thus, there is a need to detect any remaining methyl methacrylate. Raman spectroscopy is a rapid, sensitive, and non destructive method as compared to other spectroscopic, chromatographic or polarographic methods. In this study, the spectra of some lens materials (prepared from methyl methacrylate, 2-hydroxy ethyl methacrylate, Hexamethyl disiloxane and polypropylene glycol with or without the addition of crosslinker ethylene glycol dimethylacrylate) were obtained by Raman spectroscopy. It was observed that an amount of crosslinker present in the structure proves effective for the unpolymerized monomer content. None of the samples, except those containing nexamethyl disiloxane, demonstrated any monomer residue.

Biocompatible Materials↗
PubMedDate not supplied

Long-term efficacy of biomodeled polymethyl methacrylate implants for orbitofacial defects.

OBJECTIVE: To report the long-term efficacy of custom polymethyl methacrylate implants using high-resolution computed tomographic modeling in the reconstruction of complex orbitofacial defects secondary to trauma. METHODS: Nine patients with complex orbitofacial bone defects after trauma were evaluated for this retrospective, nonrandomized, noncomparative study. All the patients underwent reconstruction using custom, heat-cured polymethyl methacrylate implants. Patients were followed up postoperatively and evaluated for complications. RESULTS: Nine consecutive patients (5 men and 4 women) aged 28 to 63 years who underwent surgical reconstruction using prefabricated, heat-cured polymethyl methacrylate implants were included in the study. The interval between injury and presentation ranged from 1 month to 40 years. There were no significant complications, including infection, extrusion, or displacement of the implant. In all of the patients, wound healing was uneventful, with antibiotic drugs administered perioperatively. Mean follow-up was 4.3 years from the first visit (range, 6 months to 10 years). CONCLUSIONS: Computed tomographic biomodeled, prefabricated, heat-cured polymethyl methacrylate implants are well tolerated in the long term. Their advantages include customized design, long-term biocompatibility, and excellent aesthetic results.

Adult↗
PubMed1986

Mechanical properties of polymeric membranes obtained by radiation cast-polymerization of hydroxyalkyl and hydroxypolyethyleneglycol methacrylate monomers.

Polymeric membranes have been prepared by radiation cast-polymerization of hydroxyalkyl and hydroxypolyethyleneglycol methacrylate monomers, and the mechanical properties of the membranes before and after swelling have been studied as a function of the molecular structure of the monomers. The degree of hydration of the polymers from hydroxypolyethyleneglycol methacrylate monomers increased with increasing the number of ethyleneglycol units in the monomers, and that from hydroxyalkyl methacrylate monomers decreased with an increase in the number of methylene units. The mechanical properties such as tensile strength, tear strength, Young's modulus, and elongation at break varied with the length of the methylene and ethyleneglycol units in the monomers. It was found that flexible polymeric membranes having various properties for medical applications could be obtained by radiation cast-polymerization of hydroxyalkyl and hydroxypolyethyleneglycol methacrylate monomers.

Acrylates↗
PubMed1987

Cell responses to biomaterials. I: Adhesion and growth of vascular endothelial cells on poly(hydroxyethyl methacrylate) following surface modification by hydrolytic etching.

Hydrogels of poly(hydroxyethyl methacrylate) (polyHEMA) homopolymer do not normally support the attachment and growth of mammalian cells. By altering the surface it has been possible to dramatically change this cell-substratum interaction so that vascular endothelial cells can attach and completely populate a polyHEMA surface. While this can be achieved by copolymerisation of polyHEMA with methacrylic acid or diethylaminoethyl methacrylate, it is most conveniently achieved by brief treatment of polyHEMA hydrogel with concentrated sulphuric acid. The resultant creation of surface-COOH groups, revealed by electron spectroscopy for chemical analysis, is consistent with the hydrolytic formation of methacrylic acid on the surface layer. Surface--COOH groups created by treatment with chloric or hydrofluoric acids were not effective. Following sulfuric acid treatment, cell adhesion and growth on polyHEMA hydrogel were better than on Teflon and approached those attained on glow-discharge-treated polystyrene. The capacity of acid-treated polyHEMA to adsorb albumin or fibronectin was of the order of 100-fold or 10-fold lower respectively than either polystyrene, Teflon, or segmented polyurethane. Hydrolytic "etching" in this way is proposed as an efficient means of expanding the use of polyHEMA hydrogel as a biomaterial without modifying the overall physicochemical properties of the bulk of the material.

Acrylates↗
PubMed1989

Effect of substrate condition and substituted phenols and methacrylates on toluene diisocyanate/dentin bond strengths.

One aim of this in vitro investigation was to determine the effect of substituting four phenols and two methacrylates with vinyl functions on the dentin bond strengths of several new experimental dentin bonding agents. Another objective was to determine the effect of postextraction age and dentin level within the tooth on tensile bond strengths of these toluene diisocyanate-derived adhesives. Extracted third molars were divided into postextraction age groups and sectioned into three slices approximately 400 microns thick. The four substituted phenols were: eugenol, o-methoxyphenol, o-chlorophenol, and p-cresol. Substituted methacrylates with vinyl ligands were 2-hydroxyethyl methacrylate (HEMA) and 6-hydroxyhexyl methacrylate (HHMA). Results showed that adhesives made with o-chlorophenol, p-cresol, and methoxyphenol with HEMA were the best, while those made with eugenol and HHMA were the worst. The post extraction age of the tooth and the dentin depth had no consistent effect on most adhesive bond strengths which were generally around 10.3 MPa (1500 psi).

Acrylates↗
PubMed1993

Protein adsorption to poly(ether urethane ureas) modified with acrylate and methacrylate polymer and copolymer additives.

To understand better blood interactions with poly(ether urethane urea) (PEUU) materials, a radioimmunoassay and whole or diluted human plasma were used to characterize the presence of fibrinogen, immunoglobulin G, factor VIII/von Willebrand factor, Hageman factor (factor XII), and albumin on a PEUU formulation and on PEUU formulations modified with the amphiphilic additive Methacrol 2138F (co[diisopropylaminoethyl methacrylate (DIPAM)/decyl methacrylate] [3/1]), or with hydrophobic acrylate or methacrylate polymer or copolymer additives. The protein adsorption assay showed that PEUU films loaded or coated with Methacrol 2138F (Methacrol) or homopoly-DIPAM (h-DIPAM) adsorbed significantly lower amounts of the studied proteins than did either the base PEUU formulations or the PEUUs loaded with the more hydrophobic acrylate or methacrylate polymer additives. Experiments with Methacrol-loaded PEUUs, where the loading of Methacrol was varied from 0.25 wt% to 20.0 wt%, showed that the adsorption of each of the characterized proteins did not vary significantly throughout the Methacrol loading range, and that all Methacrol-loaded PEUU formulations adsorbed significantly lower amounts of the studied proteins than did the unloaded PEUU. Phase separation within the additive loaded PEUUs was characterized by scanning electron microscopy (SEM). The solubility parameters of the additives, as well as of the base PEUU, were calculated and used to interpret differences in phase separation of the additive modified PEUUs. The analysis showed that additives of lower solubility parameter phase-separated into fewer large microdroplets within the PEUU matrix. SEM analysis also showed that additive microdroplets were not present on the air side surface of loaded PEUUs. To explain the differences in protein adsorption to the air side of additive loaded PEUUs when compared to the base PEUU, it was assumed that the additives near this region of the solvent swollen PEUU matrix may have migrated to, at, or near the PEUU-air interface during film formation, creating an additive enriched PEUU surface region. Once at this surface region, it was suggested that dynamic surface reorientation in response to an aqueous medium ensured that the additives were able significantly to influence protein adsorption behavior only if they interacted with aqueous media more favorably than the PEUU.

Acrylates↗
PubMed2003

Comparative study of bone cements prepared with either HA or alpha-TCP and functionalized methacrylates.

The properties of bone cements prepared with both hydroxyapatite (HA) and alpha-tricalcium phosphate (alpha-TCP) and methacrylates containing acidic or basic groups are the main interest of this article. The presence of methacrylic acid or diethyl amino ethyl methacrylate as comonomers in the bone cement and both ceramic types as filler were found not to affect the amount of residual monomer, which was generally less than 4.5 wt%. In contrast, setting times, maximum temperature, and glass transition temperature were found to be composition dependent. For samples with acidic comonomer, a faster setting time, a higher maximum temperature, and higher glass transition temperatures were observed compared to those with the basic comonomer. The presence of the fillers slightly increased the setting time but did not affect the other parameters. The mechanical properties of the filled bone cements depended mainly on composition and type of testing. Both HA or alpha-TCP filled systems fulfilled the minimum compressive strength required for bone cement application, although a significantly lower value was observed for the alkaline comonomer systems. The minimum bending strength was not satisfied by any of these formulations. The tensile and shear strength of these composites ranged from 20 to 37.9 and from 18 to 27 MPa, respectively. In all cases it was higher for bone cements containing methacrylic acid. The results of this study suggest that the properties of dry unfilled bone cements prepared with MAA are comparable to CMW 3 in mechanical terms but inferior in their setting properties.

Bone Cements↗
PubMed2005

Methacrylate-based chromatographic media.

This review summarizes the preparation and application of chromatographic separation media based on methacrylate monomers with a major focus on highly crosslinked macroporous beads prepared from 2-hydroxyethyl methacrylate and glycidyl methacrylate, respectively. The effects of process variables such as composition of the polymerization mixture that includes monomers, porogenic solvents, and free radical initiator, suspension stabilizer, reaction temperature, and stirring are detailed for both classical and templated suspension polymerization. In addition, specific features of the preparation of monodisperse beads are also discussed. The performance of methacrylate-based separation media is demonstrated on numerous separations in a variety of chromatographic modes.

Chromatography↗
PubMed1988

Ablation of bone and methacrylate by a prototype mid-infrared erbium:YAG laser.

An erbium:YAG laser was used to generate 200-microseconds pulses of mid-infrared 2.94-microns light in both the single and multimode configurations. Laser pulses were focused on the surfaces of both rabbit long bones and methacrylate blocks, and the tissue response was examined histologically. The depth of thermal injury was determined by ocular micrometry. Over all energy levels tested, the erbium:YAG laser produced ablation of bone and methacrylate with minimal thermal damage to adjacent tissue. Increasing the laser energy per pulse produced increasingly wider and deeper grooves in both bone and methacrylate. However, such increase in laser energy produced a proportionately greater increase in the zone of thermal injury in methacrylate as compared with bone. These studies suggest the feasibility of a surgical erbium:YAG laser in orthopaedics and other forms of ablative surgery.

Animals↗
PubMed2005

Characterization of methyl methacrylate grafting onto preirradiated biodegradable lignocellulose fiber by gamma-radiation.

Gamma-radiation-induced graft copolymerization of methyl methacrylate onto natural lignocellulose (jute) fiber was carried out by the preirradiation method in an aqueous medium by using octylphenoxy-polyethoxyethanol as an emulsifier. The different factors that influenced the graft copolymer reaction process were investigated. In the case of radiation-dose-dependent grafting, samples irradiated in the presence of air produced up to 73% graft weight compared to 53% obtained in the case of irradiation in a nitrogen environment. By assuming Arrhenius reaction kinetics, the activation energy (E(a)) of the grafting reaction process was evaluated for different reaction temperatures. Moreover, the graft copolymer reaction was controlled by incorporating a homopolymer-inhibiting agent and three different chain-transfer agents in the reaction medium. The mechanical and thermal properties of jute fiber 'as received' and jute-graft-poly(methyl methacrylate) were also investigated. The results showed that the percentage of grafting with jute fiber has a significant effect on the properties. The kinetic parameters were evaluated from TGA thermograms by using Broido's method in the temperature range 240-350 degrees C. Scanning electron micrographs show that the structural changes on the surface of jute fibers were induced by graft copolymerization of methyl methacrylate monomer. Fiber-fiber surface friction was measured in terms of the average maximum load and the kinetic friction. SEM of jute-graft-poly(methyl methacrylate).

Biocompatible Materials↗
PubMed1986

Methacrylic acid as a teratogen in rat embryo culture.

Using day 10 rat embryos cultured in vitro, we have shown that methacrylic acid is teratogenic at concentrations ranging from 1.2 to 2.1 mM. At these concentrations, methacrylic acid produced concentration-dependent decreases in growth parameters, i.e., crown-rump length, number of somites, and embryo protein content. In addition, methacrylic acid exposure produced malformed embryos characterized primarily by abnormal neurulation. Less frequent abnormalities included hypoplasia of the prosencephalon, edema, malpositioned heart, abnormal flexion, and dilated otic vesicles. Accompanying these abnormalities was an underlying increase in methacrylic acid-induced cell death.

Acrylates↗
PubMed1984

Standardization of various applications of methacrylate embedding and silver methenamine for light and electron microscopy immunocytochemistry.

The use of butyl-methyl-methacrylate embedding and the application of the silver methenamine (SM) method as a poststaining of the immunoperoxidase-DAB (IP) procedure led to the standardization of several useful methods for the visualization of tissue antigens at the light and electron microscope level. These procedures included: 1) Standardization of the actual methacrylate embedding; 2) The IP-SM method with and without periodic acid oxidation, which provided 100% intensification of the IP staining; 3) The IP-SM method made it possible to stain semithin sections (0.5 micron), and this in turn, permitted a) clear visualization under the light microscope of the intracellular distribution of antigens and, b) staining, in several adjacent sections, of roughly the same cytoplasmic region of the same cell with different primary antisera; 4) a double immunostaining whereby the first antigen in the sequence was revealed by the IP-SM method and the second by the IP procedure; 5) standardization of the IP and the IP-SM methods for post-embedding staining of ultrathin methacrylate sections. The combined application of methacrylate embedding and the IP-SM, and the use of an appropriate fixative, resulted in an ultrastructural immunocytochemical procedure characterized by a good immunoreactivity of the tissue sections, a strong and selective immunoreaction and a well preserved ultrastructure.

Acrylates↗