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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 effect of alcohols, bonding resins, or dentin adhesives on the adhesive bond between the layers of visible light-activated composites when used as lubricant for composite instruments was investigated. The results of this study indicated that alcohols are not compatible with certain BIS-GMA-based and UEDMA-based composite systems (Herculite and Heliomolar composites were used for this investigation). Use of ethanol as a lubricant caused pure adhesive failure and low bond strength in UEDMA-based composite (Heliomolar), indicating that the bond strength was less than the cohesive strength of the composite. A bonding resin of a similar brand (or the same system) used to lubricate the composite instrument did not affect the bond strength of the bonded composite specimens. In light of this study, a bonding resin of the same resin system as the composite may be the most suitable and reliable material to be used for lubricating the composite instrument.
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PMID:Effects of four lubricants used during incremental insertion of two types of visible light-activated composites. 297

The role of dipicolinic acid (DPA) in determining the resistance of Bacillus cereus spores to u.v. and gamma radiation was investigated. B. cereus BIS-59 spores containing varying amounts of DPA were prepared by appropriate compositional adjustments in the secondary media. Compared with spores containing 6 per cent DPA (dry weight) those containing 0.8 per cent DPA were far more sensitive to u.v. radiation. Similar u.v. radiation sensitivity was also found in respect of a DPA-less mutant of B. cereus T 6A 1. Pre-treatment of DPA deficient spores (of wild type or mutant B. cereus) with DPA or the presence of DPA during irradiation resulted in increased resistance of these spores to u.v. radiation. In the range 0.2 to 1 per cent DPA content of spores of B. cereus BIS-59, a striking inverse relationship could be discerned between the DPA content and the number of spore photo-products (5-thymidyl, 5,6-dihydrothymine) formed in DNA and spore viability. The resistance of B. cereus spores to gamma radiation did not seem to be influenced by their DPA content.
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PMID:Involvement of calcium and dipicolinic acid in the resistance of Bacillus cereus BIS-59 spores to u.v. and gamma radiations. 310 Apr 69

In its present version, the Gluma system for bonding restorative resin to dentin involves the application of an enamel bonding agent prior to the composite resin. Conceivably, pretreating the dentin with solutions of amino acids, and incorporating camphorquinone and selected methacrylic monomers into the Gluma adhesive would nullify the need for the enamel bonding agent. A bond strength to dentin of 13.4 MPa was obtained in the control experiment. Using a solution of pyruvic acid and glycine as pretreatment, and an optimized adhesive mixture containing glutaraldehyde, HEMA, BIS-GMA, camphorquinone, and water, bond strengths to dentin of 14.5 MPa and to enamel of 23.3 MPa were obtained. Thus, the new Gluma bonding system gave acceptable bond strengths without the prior application of enamel bonding agents.
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PMID:Adhesion to dentin by means of Gluma resin. 314 33

The bond strengths between composite layers either cured to themselves or to other types (classes) of composites of similar or different brands were measured by using a direct tensile test (true tension). The diametral compression test for tension for each material tested was also conducted according to ADA specification No. 27. The values were used for comparison. 1. The interfacial bond strengths were generally found to be higher than the cohesive strengths of the weaker materials when cured to different types of composites or of the weak region in the specimen when composites were cured to themselves. 2. The cohesive tensile failure of the materials occurred at much lower stress levels than their corresponding diametral tensile strength (ranging from 1/4 to 1/3 of the diametral strength). 3. When two types of composites were bonded together the cohesive failure occurred consistently within the materials with lower diametral strength. Correlation was observed between the values of cohesive strength of material measured with true tension and the diametral test. 4. A urethane dimethacrylate microfilled composite bonded weakly to BIS-GMA composite, therefore, their combined use should be avoided. 5. Incremental placement produced a clinically acceptable bond strength because it exceeded or was at least comparable to the cohesive strength of the material.
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PMID:Interfacial bond strengths between layers of visible light-activated composites. 327 79

In the United States there is a new method for obtaining strong adhesive bonding between composite resins and both dentine and enamel. This experimental procedure has not reached commercial availability but several manufacturers are making preparations to supply it. The procedure comprises the sequential application of three compounds in solution. The first is an aqueous solution of ferric oxalate which conditions the dentine or enamel surface. The second is an acetone solution of a surface-active compound such as N-phenylglycine. After the acetone evaporates the excess compound is removed by the use of more solvent. The next step is the application of an acetone solution of a monomer that resembles the BIS-GMA used in composite resins but which has certain important differences. The short label for it is 'PMDM' because it is the reaction product of pyromellitic dianhydride and 2-hydroxyethylmethacrylate. When the volatile solvent quickly evaporates a thin layer of the PMDM remains on the treated dentine or enamel surface. Composite resins will then adhere strongly to these prepared surfaces, giving tensile adhesive bond strengths up to 14 MN/m2. Bond strengths of this magnitude have, on at least ten occasions, been sufficient to break pieces of dentine out of the surfaces of the extracted teeth during testing. The bond strengths to dentine obtained by this method in the laboratory are much higher than the strengths obtained with commercially available materials. The new technique is more complicated than those now in use. This creates a challenge to the dental manufacturers who must produce and supply these materials in a storage-stable form and who must provide directions that will lead to their proper use and the best results.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Bonding of restorative materials to dentine: the present status in the United States. 389 42

The initial rate of inactivation of T4 phage by solutions of [Pt(NH3)2Cl2], [PtenCl2] and [Pten(H2O)2] (NO3)2 at fixed values of pH is strongly reduced by phosphate buffer, slightly reduced by acetate buffer and apparently not influenced by bis(2-hydroxyethyl)aminotris(hydroxymethyl)methane (BIS-Tris) buffer and HEPES buffer. The phosphate abolishes the antiphage activity of the platinum complexes probably by some sort of complex formation. This together with dimerization reactions qualitatively explains the tailing off of the phage inactivation rate. High concentrations of NaNO3 as the salt medium give increased phage inactivation rates, which are also strongly pH-dependent.
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PMID:Phosphate buffer and salt medium concentrations affect the inactivation of T4 phage by platinum(II) complexes. 401 1

The traditional infrared spectroscopic methods for assessing the degree of polymerization of dental monomers are often hampered by the difficulties of sample preparation and, in the case of composites, by interference from the filler component. These difficulties may be circumvented by the use of another technique, differential scanning calorimetry (DSC). In this preliminary investigation, DSC was used to ascertain the degree of vinyl polymerization of an experimental monomer system consisting of seven parts BIS-GMA and three parts TEGDMA (triethylene glycol dimethacrylate). Thermally-activated polymerizations of this monomer system were studied using benzoyl peroxide (BP) as the initiator. Both the heating rate and the concentration of BP affected the percent of reacted vinyl groups. For a BP concentration of 0.39% and heating rates of 10 degrees/min and 2.5 degrees/min, conversions were 73 and 38%, respectively. Chemically-activated polymerizations using BP and fast-acting amine accelerators (e.g., p-t-butyl-N,N-dimethylaniline) gave approximately the same results (e.g., 50% conversion) as those obtained with slower-acting promoters (e.g., ascorbyl palmitate). Experimental difficulties are encountered in observing an exotherm with the very reactive accelerators unless the other parameters (e.g., BP or inhibitor content) involved in the reaction are adjusted accordingly. As a method for evaluating the performance of various dental monomers, initiator systems, and inhibitors, DSC has great potential utility.
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PMID:Extent of polymerization of dental resins by differential scanning calorimetry. 621 91

Most composite materials in dentistry used today, contain resins based on dimethacrylates. BIS-GMA [2,2-bis-(4-(2-hydroxy-3-methacryloxypropoxy)phenyl)propane], the addition reaction product of bisphenol A and glycidyl methacrylate or an epoxy resin and methacrylic acid, is used most extensively. More recently, dimethacrylates based on bisphenol A, with various chain lengths have appeared on the market as a substitute for or in addition to BIS-GMA. Such compounds are BIS-MA [2,2-bis-(4-(methacryloxy)phenyl)propane], BIS-EMA [2,2-bis-(4-(2-methacryloxyethoxy)phenyl)propane] and BIS-PMA [2,2-bis-(4-(3-methacryloxypropoxy)phenyl)propane]. Increasing interest in the radiaton cure of coatings and printing inks have focused attention on these substances and on epoxy diacrylates as radiation-curable resins. The sensitizing capacity of the different acrylates based on bisphenol A or epoxy resin have been investigated with the guinea pig maximization test. The pattern of simultaneous reactivity of the compounds was also studied. Epoxy diacrylate [2,2-bis-(4-(2-hydroxy-3-acryloxy-propoxy)phenyl)propane], BIS-EMA and BIS-MA are shown to be strong sensitizers, while the linear fraction of BIS-GMA and its isomers and BIS-PMA have none or a low sensitizing capacity. The impurities in the BIS-GMA and BIS-MA batches seem to have high allergenic potential. These results stress the importance of a pure substance when discussing allergenicity and cross reactions.
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PMID:The sensitizing potential of di-(meth)acrylates based on bisphenol A or epoxy resin in the guinea pig. 623 44

The aim of this study was to determine how otherwise acceptable diluent monomers affect the marginal adaptation of BIS-GMA-based composites. Based on the results of the investigation, the following conclusions can be drawn: 1. Addition to dimethacrylate diluents containing (CH2) recurring units generally yields composites having better marginal adaptation than do those containing (CH2 CH2 O) groups. Best marginal adaptation for a single diluent is obtained for compositions using 1, 4 and 1, 10-polymethylene glycol dimethacrylate as diluent. 2. Marginal adaptation is improved on lowering the diluent concentration. Optimum adaptation will be obtained for a formulation containing a minimum percentage of diluent with clinically acceptable working properties. 3. Volume changes on temperature cycling resulting from differences in thermal expansion coefficients of composites do not effect the marginal integrity as much as does curing shrinkage.
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PMID:Marginal adaptation of BIS-GMA-based composites containing various diluents. 645 54

Bis (2,3-dibromopropyl) phosphate (BIS-BP) is one of two identified metabolites of Tris (2,3-dibromopropyl) phosphate (TRIS-BP). We have previously shown that BIS-BP is more acutely nephrotoxic than TRIS-BP. We now report the effect of sex and inhibition of drug metabolism on BIS-BP toxicity. Compared to male rats, age-matched female rats developed less severe and extensive structural damage after BIS-BP. Renal dysfunction, as indexed by serum creatinine and in vitro renal cortical uptake of para-aminohippurate and N-(14C) methylnicotinamide was similar in males and females. Pretreatment of males with the drug metabolism inhibitor, cobaltous chloride, reduced both functional and structural evidence of BIS-BP toxicity. In separate studies, there was no difference in the distribution of radiolabel in male and female rats three days after administration of 14C-TRIS-BP. These studies showing that female rats are resistant to acute BIS-BP structural damage may explain the previously reported lack of carcinogenicity of TRIS-BP in female rats. The reduction of BIS-BP toxicity by CoCl2 suggests that unidentified, nephrotoxic metabolites exist and are responsible for part of the nephrotoxicity of BIS-BP.
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PMID:Bis (2,3-dibromopropyl) phosphate nephrotoxicity: effect of sex and CoCl2 pretreatment. 682 91


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