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Query: EC:2.3.1.177 (BIS)
 957 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism of the hydrolytic deterioration of the silane coupling agent layer on silica filler of composite resin was examined. As a result of the desorption of the absorbed silane molecules, the contact angle between water drop and the silica plate treated with the silane coupling agent decreased when the plate was soaked in hot water and the rate of the decrease in the contact angle leveled off with an increase in the concentration of the silane coupling agent solution. With an increase in the soaking time in hot water, the strength of adhesion of poly (BIS-GMA) to the silica treated with the silane coupling agent decreased and the position of the fracture shifted from the matrix resin (adherend failure) to the silane coupling layer (adhesion failure). The time when the adhesion failure took place depended on the concentration of the silane coupling agent solution and there was the optimum concentration for water-resistant adhesion.
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PMID:[Study on surface treatment of silica filler. Hydrolytic deterioration of the silane coupling layer]. 249 Feb 2

A cone-plate viscometer was employed for studying the rheological characteristics of certain unfilled resins and etching gels. Of these, BIS-GMA monomer and its diluted mixtures exhibited Newtonian, dilatant and thixotropic behaviour depending on the shear rate. Other unfilled resins also exhibited various types of behaviour. At high shear rates reproducible hysteresis loops were obtained for etching gels which may be useful in characterization.
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PMID:The use of a cone and plate viscometer for determination of flow properties of unfilled resins and etching gels. 252 63

7 patients were occupationally sensitized to dental composite resin products (DCR): 6 dental nurses and 1 dentist. All had a positive patch test to their DCR. 2 independent types of allergy were seen; (a) aromatic epoxy acrylate, and/or (b) aliphatic acrylates. 4 out of 5 patients reacted to BIS-GMA, the most widely used aromatic epoxy acrylate in DCR, but not the dentist. She and 2 dental nurses were allergic to aliphatic acrylates, including triethylene glycol dimethacrylate (TREGDMA) and triethylene diglycol diacrylate (TREGDA). 4 patients were allergic to epoxy resin (ER) (containing mainly MW 340), possibly an impurity in some DCR. 2 patients were also allergic to methyl methacrylate (MMA): the dentist, had been exposed to MMA, but the nurse's exposure was uncertain. 1 patient was also allergic to rubber gloves, 2 to rubber chemicals but not their gloves, and 5 to disinfectants used. diagnosis was delayed as long as 13 years in spite of previous patch testing. Dermatologists need to use the patients' own DCR and the (meth)acrylate series for patch testing. No dental nurses could continue their occupation, but the dentist could occasionally handle DCR if wearing PVC gloves. Dental personnel need to know about the risks of DCR, and use no-touch techniques and protective gloves.
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PMID:Allergic contact dermatitis from dental composite resins due to aromatic epoxy acrylates and aliphatic acrylates. 252 51

The use of short glass fibers as a filler for dental restorations or cement resins have not been examined extensively. The mechanical properties and untreated glass fibers (5 microns dia x 25 microns) in Bis-phenol A glycidyl methacrylate (BIS-GMA) diluted with triethylene-glycol dimethacrylate (TEGDMA) resin were investigated for possible use as a restorative dental composite or bone cement. Compression, uniaxial tension and fracture toughness tests were conducted for each filler composite mixtures of 40, 50, 60 and 70%. Set time and maximum temperature of polymerization were determined. The results show that the elastic modulus, tensile strength and compressive strength are dependent on the percent of filler content. Elastic modulus and compressive yield (0.2%) strength of silane treated glass fibers filled composite increased from 2.26 to 4.59 GPa and 43.3 to 66.6 MPa, respectively, wtih increasing the filler content while the tensile strength decreased from 26.7 to 18.6 MPa. The elastic modulus of the untreated composite was less than that of the silane treated fiber composite. The tensile strength and compressive strengths were 20 to 50% lower than those of silane treated composites. The fracture toughness of the silane treated glass fiber additions were not significantly different from the untreated additions. The highest fracture toughness was obtained at 50% filler content with 1.65 MPa m.5. Set time increased from 3.5 to 7.7 minutes with increased filler content and peak temperature dropped from 68.3 to 34 degrees C. The results of this study indicate that the addition of silane coated glass fiber to BIS-GMA resin increased the elastic modulus, tensile and compressive strengths compared with non-treated fibers. The addition of either treated or non-treated fibers increased the set time of the material and decreased the maximum temperature.
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PMID:Mechanical properties of BIS-GMA resin short glass fiber composites. 253 Feb 34

A new resin dentin adhesive consisting of a primer (phosphonate dimethacrylate) and bonding agent (phosphonated BIS-GMA) was evaluated with bond strength tests, marginal microleakage studies, and SEM examination. The mean bond strength to dentin was 15.6 +/- 3.7 MPa. Microleakage studies found no marginal leakage at the enamel cavosurface margin and very minimal microleakage at the dentin/cementum margins. SEM examination showed that the primer was very effective in modifying the smear layer.
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PMID:Shear bond strength, microleakage and SEM study of the XR Bond adhesive system. 253 77

An automatic microprocessor complex is used for measurements, automatic calculations and registration on the screen of the TV monitor; along with the 24 hemodynamic ADPD parameters at the tetrapolar rheograms, ECG and arterial pressure. The complex is based on BIS K180IBMI.
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PMID:[Operative automated monitor of hemodynamics using a tetrapolar rheogram]. 262 2

The adsorption of 4-methacryloxyethyl trimellitate anhydride (4-META) was studied from ethanol and dichloromethane onto synthetic hydroxyapatite (containing about 1.5 monolayers of physisorbed water) in order to study its role in restorative composite bonding to teeth. The adsorption isotherm of 4-META was S-shaped and reversible from ethanol, and followed the Langmuir plot at lower concentrations. The isotherm was irreversible from dichloromethane, and a constant amount of adsorbate was removed from the solutions above a certain concentration. The irreversibly adsorbed compound was completely removed by washing with ethanol. Therefore, the bonding between teeth and the restorative resin containing 4-META as a coupling agent is micromechanical and not chemical in nature. An analysis of isotherms showed that the benzene rings of the adsorbate molecules lie flat on the surface for both solvents. The molecules adsorbed from ethanol rotate about the solvent-modified (esterified) or unmodified carboxylic anhydride moieties with methacrylate hydrocarbon groups which are folded upward. However, the molecules adsorbed from dichloromethane remain fixed to the surface without rotation, and their methacryloxyethyl groups are folded over the rings. The diametral tensile strength of a BIS-GMA polymer with adsorbate-covered apatite was approximately equal to that of the composite filled with untreated apatite.
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PMID:Adsorption of 4-methacryloxyethyl trimellitate anhydride (4-META) on hydroxyapatite and its role in composite bonding. 264 29

A radioligand that selectively labels beta 1-adrenoceptors, 3H-(-)-bisoprolol (3H-BIS), is introduced. The binding properties of 3H-BIS to membrane particles of kitten heart are compared with the blocking properties of (-)-bisoprolol against stimulant effects of (-)-adrenaline and (-)-noradrenaline in heart preparations of kitten and guinea pig. 1. On kitten heart tissues (-)-bisoprolol antagonized the positive chronotropic and inotropic effects of catecholamines competitively. The effects of (-)-adrenaline were antagonized considerably less by (-)-bisoprolol than the corresponding effects of (-)-noradrenaline on sinoatrial pacemakers. The antagonism was nearly the same against both (-)-adrenaline and (-)-noradrenaline in left atria and papillary muscles. The data were analyzed with a model for 2-receptor subtypes by non-linear regression. Equilibrium dissociation constants KB (mol/l; -log KB = pKB) for a high-affinity beta 1-adrenoceptor of 8.8 and for a low-affinity beta 2-adrenoceptor of 7.0 were estimated in the three classes of tissues. In kitten sinoatrial pacemaker beta 1-adrenoceptors contribute 76% to the stimulus induced by (-)-adrenaline and 97% to the stimulus induced by (-)-noradrenaline. In ventricle and left atrium beta 1-adrenoceptors contribute 97-99% and 100% to the stimulus caused by (-)-adrenaline and (-)-noradrenaline, respectively. 2. Both 3H-BIS and unlabelled (-)-bisoprolol caused competitive blockade of the positive chronotropic effects of (-)-noradrenaline in guinea-pig right atria. pKB-values of 8.7 were estimated for both unlabelled and tritiated (-)-bisoprolol. The positive chronotropic effects of (-)-adrenaline were antagonized considerably less by (-)-bisoprolol than those of (-)-noradrenaline in guinea-pig atria. In the presence of low concentrations of beta 2-selective ICI 118,551, which did not antagonize beta 1-adrenoceptor mediated effects, (-)-bisoprolol antagonized positive chronotropic effects of (-)-adrenaline to the same extent as those of (-)-noradrenaline. The results are consistent with the concept of a significant role of sinoatrial beta 2-adrenoceptors of guinea pig for the effects of (-)-adrenaline but not for those of (-)-noradrenaline. 3. 3H-BIS associated and dissociated quickly with and from ventricular beta 1-adrenoceptors. A koff of 1.0 min-1 was estimated. An equilibrium dissociation constant pKL* of 8.2 for 3H-BIS was estimated from saturation binding.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Direct labelling of myocardial beta 1-adrenoceptors. Comparison of binding affinity of 3H-(-)-bisoprolol with its blocking potency. 286 49

A dental assistant developed sensitivity to dental restorative materials within 3 months of starting to use them. They contained the epoxy acrylate BIS-GMA, which is the most commonly used dimethacrylate monomer in dental composite restorations. She was positive to a patch test with BIS-GMA, which was the probable allergen, and epoxy resin, but this substance was not present in the materials used, as shown by high performance liquid chromatography. The patient was also allergic to the disinfectant Desimex i containing dodecyl diaminoethyl glycine.
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PMID:Occupational dermatitis due to an epoxy acrylate. 294 56

This study evaluated the tensile bond strength of Conclude luting composite to dentin under different environmental conditions with Scotchbond dental adhesive, the FNP system, and unfilled BIS-GMA resin used as bonding agents. Although the bonding systems reportedly yield high tensile bond values to enamel, large differences were observed in this study for bond values to dentin. Only the FNP bonding system produced consistently high tensile load values to dentin under the three environmental conditions tested.
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PMID:Bond strength of a luting composite to dentin with different bonding systems. 295 95


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