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PubMed2000

Comparison of chromatographic ion-exchange resins. I. Strong anion-exchange resins.

A comparative study has been undertaken on various strong anion-exchangers to investigate the pH dependence, titration curves, efficiency, binding strength, and dynamic capacity of the chromatographic resins. The resins tested included: Macro-Prep 25Q, TSK-Gel Q-5PW-HR, Poros QE/M, Q Sepharose FF, Q HyperD 20, Q Zirconia, Source 30Q, Fractogel EMD TMAE 650s, and Express-Ion Q. Testing was performed with five different proteins: Anti-FVII Mab (IgG), aprotinin, BSA, lipolase, and myoglobin. The dependence of pH on retention varies from generally low to very high for proteins with low pI. No direct link between pH dependence on retention and titration curves of the different resins was observed. Efficiency results show the expected trend of lower dependence of the plate height with increasing flow-rate of resins for medium and high pressure operation compared to the soft resins. Binding to the anion-exchange resins as a function of ionic strength may vary depending on the specific protein. Generally, binding and elution at a high salt concentration may be performed with Poros QE/M or Macro-Prep 25Q, while binding and elution at low salt concentration may be done with TSK-Gel Q-5PW. Dynamic capacities are strongly dependent on the specific protein employed and for some resins dependent on the flow-rate. A general good agreement was obtained between this study and data obtained by suppliers for the dynamic capacity. The results of this study may be used for selection of resins for testing in process development, however, the data does not tell anything about specific selectivity differences or resolution between a target protein and a given impurity. None of the resins studied here should be regarded as good or bad, but more or less suitable for a specific purpose, and only testing for the specific application will determine which one is the optimal resin.

Anion Exchange Resins↗
PubMed1989

Contact allergy to Manilla resin. Nomenclature and physico-chemistry of Manilla, kauri, damar and copal resins.

16 cases of allergic eczema from a resin used in a surgical adhesive (Alphacopal) are described. Because of the extreme confusion regarding the nomenclature and origin of the resins called copals and damars, this report attempts to give a terminological, botanical, physico-chemical and allergological restatement of this problem. Copals and damars are produced by trees belonging to the Araucariaceae, Caesalpiniaceae, Dipterocarpaceae and Burseraceae families. We suggest that the word "copal" be reserved for the resins of the Caesalpiniaceae and that of "damar" for the resins of the Dipterocarpaceae. The resins of the Araucariaceae are special products that may be called Manilla resin and kauri resin, which are relatively different from each other. As far as the soft resins of the Burseraceae are concerned, it would be appropriate to use the word "elemi". The component resin of the surgical adhesive implicated (Alphacopal) is a Manilla resin, produced by a variety of Agathis dammara (Lamb.) Rich., native to the Philippines. We suggest 3 allergen screening series. Finally 2 pseudo-cross-sensitivities are mentioned.

Adhesives↗
PubMed1990

Staining sections of water-miscible resins. 1. Effects of the molecular size of stain, and of resin cross-linking, on the staining of glycol methacrylate embedded tissues.

Penetration of hydrophilic acid and basic dyes into sections cut from glycol methacrylate (GMA)-embedded tissues was studied; as were the effects on such staining of superficial coatings of thin layers of GMA. Dye size was a major factor in controlling penetration of resin and staining of tissues. 'Large' dyes (greater than 1000 Da) entered GMA very slowly, and only stained those tissue components poorly infiltrated by resin. 'Small' dyes (less than 550 Da) penetrated GMA readily, and stained tissue components whether or not they were resin-infiltrated. Dyes of intermediate size penetrated the resin, but the staining of resin-infiltrated tissue elements was slow. Background staining of resin also varied with dye size. Large dyes gave no staining of GMA. Small dyes did, but were readily removed by water washing. Dye of intermediate size penetrated resin slowly, and once inside were lost slowly. This gave background staining which required use of the plasticizing solvent ethanol for its removal. Increases in resin cross-linking also reduced staining rates. As a consequence, it is possible to predict the probable suitability, or otherwise, of various staining reagents proposed for use with GMA sections; and also the probable influences of histoprocessing on stain penetration. In particular it is suggested that penetration of colloidal metals and macromolecular reagents (e.g. labelled antibodies and lectins) will be limited to resin-free structures, and to the surface of resin sections. The use of superficial GMA coatings as convenient semipermeable membranes for enzyme histochemistry is also noted.

Animals↗
PubMed1990

[Visible light cured resin. Chronological change in mechanical properties of matrix resin immersed in MeOH].

Monomer composition was examined to improve durability of matrix resin of visible light cured composite resin. As a monomer, five kinds of cyclophosphazene monomers, two kinds of commercial monomers and a mixture of commercial monomers were prepared to the visible light cured resins. The mechanical properties of these set products were examined with time after immersion in MeOH, an aging accelerating solvent. Compressive strength of the resins using cyclophosphazene monomers tended to decrease with time, but it increased in accordance with the increase of the number of polymerization group. Compressive strength of the resins using commercial monomers tended to decrease, but that using the BMPEPP monomer tended to increase with time. Yield point of the resins with the cyclophosphazene monomer 4 PN-(EMA)8 tended to increase with the time but that of the resins with other cases monomers decreased. The yield point of all three resins made using commercial monomers tended to decrease with time, but the rate of decrease was small for BMPEPP monomer. Compressive elastic modulus of the resins using cyclophosphazene monomers tended to increase with time when the number of polymerization group was 6-8, while it decreased when the number was 4-5. When commercial monomers were used, it tended to decrease with time, but the rate of decrease was small for the BMPEPP monomer. Transverse strength of the resins using cyclophosphazene monomers showed a tendency to decrease with time. When a commercial monomer was used, cracks appeared in the Bis-GMA+Tri-EDMA monomer after 7 days, and with the other two monomers, the transverse strength tended to decrease with time, though the rate of decrease was small for the BMPEPP monomer. Transverse elastic modulus tended to decrease with time, but the rate of decrease was small for the BMPEPP monomer.

Composite Resins↗
PubMed1996

Properties of resin-modified glass-ionomer restorative materials and two polyacid-modified resin composite materials.

The objective of the study was to evaluate the physical properties of four resin-modified glass-ionomer cements (Fuji II LC, Ionosit Fil, Vitremer, Photac-Fil) and two polyacid-modified resin composite materials (Dyract and Variglass VLC)). They were compared with a hybrid resin composite (blend-a-lux) and a chemically cured glass-ionomer cement (ChemFil Superior). The compressive strength, flexural strength, modulus of elasticity, and surface microhardness of the resin-modified glass-ionomer materials and the polyacid-modified resin-composite materials were inferior to those of the hybrid resin composite and similar to those of the conventional glass-ionomer cement. The hybrid resin composite exhibited the lowest resistance to wear caused by brushing. Some of the materials showed a marked decrease in hardness at depths exceeding 2.0 mm. Generally, the strength properties of the tested resin-modified glass-ionomer materials and the polyacid-modified resin composite materials were inferior to those of the hybrid resin composite.

Chemical Phenomena↗
PubMed1999

Comparison of bracket debonding force between two conventional resin adhesives and a resin-reinforced glass ionomer cement: an in vitro and in vivo study.

The purpose of this study was to compare the debonding force of orthodontic brackets bonded with two conventional resin adhesives (Resilience L3 and Light Bond) and a resin-reinforced glass ionomer cement (Fuji Ortho LC). For the in vitro part of the study, 80 extracted premolars were randomly divided into four groups. In groups A and B, brackets were bonded to unetched enamel using Fuji Ortho LC cement in wet and dry conditions, respectively. In groups C and D, brackets were bonded to etched enamel using Resilience L3 and Light Bond, respectively. Debonding force was determined using a servohydraulic testing machine at a crosshead speed of 1 mm/min. Data was analyzed using the ANOVA and Tukey-Kramer multiple comparison test at p<0.05. A significant difference was found in debonding force between unetched Fuji Ortho LC and the two conventional resins. There was no significant difference between the two conventional resins or between unetched resin-reinforced glass ionomer in the wet and dry conditions. For the in vivo part of the study, 30 patients were randomly assigned to one of the three bonding material groups. Bracket survival rates and distributions were obtained by following these patients for 1.2 years. Data was analyzed using the Kaplan-Meier product-limit estimates of survivorship function. Bond failure interface was determined using a modified adhesive remnant index (ARI). These results showed no significant difference between survival rates and distributions among the three bonding materials with respect to the type of malocclusion, type of orthodontic treatment, or location of bracket. There were significant differences between survival distributions of males and females in the unetched Fuji Ortho LC group and among type of teeth in the conventional resin groups. The predominant mode of bracket failure for the unetched Fuji Ortho LC cement was at the enamel-adhesive interface, and for conventional resins, the enamel-adhesive interface and the bracket-adhesive interface. These results suggest that resin-reinforced glass ionomer cement can withstand occlusal and orthodontic forces despite having a bond strength lower than that of conventional resin adhesives.

Acid Etching, Dental↗
PubMedDate not supplied

Effect of surface treatments on the bond strength between composite resin and acrylic resin denture teeth.

PURPOSE: This investigation studied the effects of 3 surface treatments on the shear bond strength of a light-activated composite resin bonded to acrylic resin denture teeth. MATERIALS AND METHODS: The occlusal surfaces of 30 acrylic resin denture teeth were ground flat with up to 400-grit silicon carbide paper. Three different surface treatments were evaluated: (1) the flat ground surfaces were primed with methyl methacrylate (MMA) monomer for 180 seconds; (2) light-cured adhesive resin was applied and light polymerized according to the manufacturer's instructions; and (3) treatment 1 followed by treatment 2. The composite resin was packed on the prepared surfaces using a split mold. The interface between tooth and composite was loaded at a cross-head speed of 0.5 mm/min until failure. RESULTS: Analysis of variance indicated significant differences between the surface treatments. Results of mean comparisons using Tukey's test showed that significantly higher shear bond strengths were developed by bonding composite resin to the surfaces that were previously treated with MMA and then with the bonding agent when compared to the other treatments. CONCLUSION: Combined surface treatment of MMA monomer followed by application of light-cured adhesive resin provided the highest shear bond strength between composite resin and acrylic resin denture teeth.

Acrylic Resins↗
PubMed1993

The extent of polymerization of Class II light-cured composite resin restorations; effects of incremental placement technique, exposure time and heating for resin inlays.

The extent of polymerization of light-cured composite resins cured in relatively large class II cavities was estimated by measuring Knoop hardness on sectioned surfaces of resin restorations. The influences of the incremental placement technique, exposure time, and post-curing of resin inlay on the extent of polymerization of two different resin materials were examined. For both MFR type (HE) and hybrid type (P50) materials, the 3-step incremental placement technique was superior when the cavity was restored by the direct filling method. For resin inlays, the post-heating improved the conversion of resin restorations. However, because the final degree of conversion of resin attained by heating was influenced by the initial conversion of the resin at the stage of light-curing, the 2-step incremental placement technique was recommended at the light-curing stage for even resin inlays. As the exposure time is influenced by the transmittance of material and the intensity of activator light, it should be optimized in accordance with manufacturers' directions.

Acrylic Resins↗
PubMed2000

The effect of secondary curing of resin composite on the adherence of resin cement.

PURPOSE: The aim of this study was to measure the adherence between a resin cement and a resin composite polymerized with and without an additional secondary cure of the resin composite. MATERIALS AND METHODS: The resin cement was 3M Opal Luting Composite and the resin composite was Z-100. The resin composite was either polymerized by light only, or given an additional secondary cure at 110 degrees C for 10 min. For each curing mode, the composite was either ground on carborundum paper #1000 or sandblasted with alumina powder. The adherence was determined as bond strength and as bond energy. RESULTS: Without sandblasting of the resin composite, the heat treatment resulted in reduced adherence both in the bond strength and the bond energy mode of measurement. With sandblasting, only the bond energy was reduced as a consequence of the heat treatment. CONCLUSION: On the basis of the experiments conducted, it may be concluded that secondary cure of resin composites takes place at the expense of the adherence to the resin cement.

Adhesiveness↗
PubMed2007

Sorption kinetics of ethanol/water solution by dimethacrylate-based dental resins and resin composites.

In the present investigation the sorption-desorption kinetics of 75 vol % ethanol/water solution by dimethacrylate-based dental resins and resin composites was studied in detail. The resins examined were made by light-curing of bisphenol A glycol dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), bisphenol A ethoxylated dimethacrylate (Bis-EMA), and mixtures of these monomers. The resin composites were prepared from two commercial light-cured restorative materials (Z100 MP and Filtek Z250), the resin matrix of which is based on copolymers of the above-mentioned monomers. Ethanol/water sorption/desorption was examined in both equilibrium and dynamic conditions in two adjacent sorption-desorption cycles. For all the materials studied, it was found that the amount of ethanol/water sorbed or desorbed was always larger than the corresponding one reported in literature in case of water immersion. It was also observed that the chemical structure of the monomers used for the preparation of the resins directly affects the amount of solvent sorbed or desorbed, as well as sorption kinetics, while desorption rate was nearly unaffected. In the case of composites studied, it seems that the sorption/desorption process is not influenced much by the presence of filler. Furthermore, diffusion coefficients calculated for the resins were larger than those of the composites and were always higher during desorption than during sorption. Finally, an interesting finding concerning the rate of ethanol/water sorption was that all resins and composites followed Fickian diffusion kinetics during almost the whole sorption curve; however, during desorption the experimental data were overestimated by the theoretical model. Instead, it was found that a dual diffusion-relaxation model was able to accurately predict experimental data during the whole desorption curve. Kinetic relaxation parameters, together with diffusion coefficients, are reported for all resins and composites.

Absorption↗
PubMed1989

An in vitro evaluation of a visible light-cured resin as an alternative to conventional resin bonding systems.

An in vitro study of 69 premolars was conducted to evaluate a visible light-cured resin system used in orthodontic bonding. The material was evaluated under various parameters to determine its relative value as an alternative to the conventional chemically activated resin systems. The 30-hour bond strength for the visible light-cured resin system was approximately one half of that found for a chemically cured resin system. Initial 1-hour bond strength of the visible light-cured resin system was found to be only 26% of the 30-hour bond strength. Enamel loss associated with debonding and subsequent cleanup of the visible light-cured resin was approximately one half of that found with the chemically cured, heavily filled resin. With the visible light-cured resin system, cleanup of remaining resin required the use of hand scalers only.

Composite Resins↗
PubMed2005

Shear bond strength of Bis-GMA resin and methacrylated dendrimer resins on silanized titanium substrate.

OBJECTIVES: The study compared the bond strengths of three resins, Bis-GMA and two novel experimental methacrylated polyester dendrimer resins to grit-blasted titanium substrate with three silanes. METHODS: Two commercial dental silanes (ESPE Sil and Monobond-S) and an experimental 0.5 vol% 3-methacryloxypropyltrimethoxysilane were applied to grit-blasted Ti substrates. Light-polymerizable resins of Bis-GMA and methacrylated dendrimer were applied to the grit-blasted Ti substrate with polyethylene molds. The substrates with resin stubs (n = 10) were thermocycled (6000 cycles, 5-55 degrees C) or kept in water (37 degrees C, 24 h). The shear bond strength of the resin was measured at a crosshead speed of 1.0 mm min(-1). The surface examination, before and after silanization, was made with a scanning electron microscope (SEM). The silane reactions on the Ti surface were monitored by Fourier transform infrared spectrometry. RESULTS: Statistical analysis (ANOVA) showed that the highest shear bond for thermocycled samples was obtained for Bis-GMA with Monobond-S (19.4 MPa, standard deviation (SD) 7.1 MPa), and after water storage with a laboratory-made silane (26.4 MPa, SD 8.1 MPa). The dendrimer and Bis-GMA resins conferred equal bonding properties to grit-blasted titanium after thermocycling. The silane, resin type, and storage conditions significantly affected the shear bond strength (p < 0.001 for all factors). SEM images suggested a mainly cohesive type of bonding failure. SIGNIFICANCE: A dendrimer based resin and the Bis-GMA resin systems conferred statistically equivalent bonding properties to silica-coated Ti after thermocycling.

Analysis of Variance↗
PubMed1976

Occupational eczema from para-tertiary-butylphenol formaldehyde resins: a review of the sensitizing resins.

The first case of allergy due to para-tertiary-butylphenol formaldehyde resins (PTBP resins) were found in 1958 in the shoe-making industry. These resins are found in certain neoprene adhesives. PTBP resin hypersensitivity may be due either to the para-tertiary-butylphenol, to the resin itself or less frequently to the formaldehyde. These resins may cause occupational allergy (in the automobile industry and chiefly in the shoe-making industry) and non-occupational allergy (footwear and clothing hypersensitivity). Patients allergic to PTBP resins have been found to show a cross-reaction to other resins such as Alresen PA 103, Schenectady SP 126 and Schenectady SP 154. The authors give a reference list of sensitizing neoprene adhesives and PTBP resins so that manufacturers can limit the use of these products as far as possible.

Dermatitis, Occupational↗
PubMed2006

Effect of light curing tip distance and resin shade on microhardness of a hybrid resin composite.

Resin composite shades and resin composite polymerization performed with a distanced light tip are factors that can affect polymerization effectiveness. This in vitro study aimed to evaluate the influence of curing tip distance and resin shade on the microhardness of a hybrid resin composite (Z250-3M ESPE). Forty-five resin composite specimens were randomly prepared and divided into nine experimental groups (n = 5): three curing tip distances (2 mm, 4 mm, and 8 mm) and three resin shades (A1, A3.5, and C2). All samples were polymerized with a continuous output at 550 mW/cm(2). After 24 hours, Knoop microhardness measurements were obtained on the top and bottom surfaces of the sample, with a load of 25 grams for 10 seconds. Five indentations were performed on each surface of each sample. Results showed that bottom surface samples light-cured at 2 mm and 4 mm presented significantly higher hardness values than samples light-cured at 8 mm. The resin shade A1 presented higher hardness values and was statistically different from C2. The resin shade A3.5 did not present statistical differences from A1 and C2. For the top surface, there were no statistical differences among the curing tip distances. For all experimental conditions, the top surface showed higher hardness values than the bottom surface. It was concluded that light curing tip distance and resin shade are important factors to be considered for obtaining adequate polymerization.

Color↗
PubMed1989

[Polymerization of visible-light cured veneering resins. 3. Influence of conversion on the bond strength of opaque resins].

New light-curable adhesive opaque resins were prepared using 4-methacryloxyethyl trimellitate anhydride (4-META), triethylene glycol dimethacrylate (TEGDMA), di (methacryloxyethyl) trimethylhexamethylene diurethane (UDMA) and titanium dioxide. The purpose of this study was to investigate the relation between the conversion of opaque resins and the bond strengths. Amounts of residual monomers in the bulk-photo-polymerized resins with various compositions were determined by high-performance liquid chromatography. Shear bond strengths of light-cured opaque resins joined to surface-treated Au-Ag-Pd alloy were measured with various primers, components and curing conditions. Photo-polymerized resins which contained mehyl methacrylate (MMA) showed lower conversion compared with bifunctional methacrylate resins. Favorable shear bond strengths were obtained from TEGDMA/UDMA based opaque resins. The opaque resins without MMA bonded strongly to heated and 4-META primed Au-Ag-Pd alloy and 22-23 M Pa strengths were maintained after 20,000 thermocycles. The results revealed that the conversion of MMA with photo-initiater system was lower than that of bifunctional methacrylate, which affected bond strength of opaque resins.

Acrylic Resins↗
PubMed1991

An in vitro study of the tensile strength of composite resins repaired with the same or another composite resin.

Interfacial tensile bond strengths of self-cured and light-activated composite resins, repaired with the same or another composite resin were measured. The bond strengths were measured as a function of age of the substrate or as a function of the adhered surface treatment. One control group of solid resin samples was tested for tensile strength. Other groups of specimens, matured for 48 hours, 7 days, and 1 year, were cut in half and ground flat before a fresh mass of composite resin was added. Six groups were coated with a thin layer of intermediate resin or bonding agent before the fresh composite resin was added. In general, the repaired composite resins revealed lower strength than did the cohesive samples, with bond strengths ranging from 19% to 52% of the strengths of the unrepaired resins. The intermediate resin increased the bond strength in all cases.

Composite Resins↗
PubMed1979

Detection of drugs using XAD-2 resin. I:Choice of resin, chromatographic conditions, and recovery studies.

Amberlite XAD-2, a nonionic polystyrene divinylbenzene resin, was first used for the analysis of drugs in urine and a number of reports have described the development at optimal conditions for extraction, including type of resin columns, pH conditions, and eluting solvents. XAD-4 and XAD-7 resins were compared to the similarly structured XAD-2 resin and no significant advantage over the XAD-2 resin for drug screening was observed. A quantity of 5 to 6 g of resin was found to have sufficient capacity for the extraction of 200 ml of pentobarbital solution (1 mg/100ml). A column flow rate of approximately 15 ml/min (gravitational flow) was sufficient for analysis and slower rates were not more efficient. A mixture of ethyl acetate and 1,2-dichloroethane (3:2) was found to give best overall recovery (66 to 94%) of drugs, the resulting extracts being reasonably free of interfering substances. A pH value of 8.5 is recommended as optimum for comprehensive analysis of acidic and basic drugs. Recovery studies were conducted on spiked samples to determine drug losses occuring during various steps in the XAD-2 extraction procedure for four acidic (amobarbital, secobarbital, pentobarbital, and phenobarbital) and four basic (morphine, codeine, meperidine, and methadone) drugs. A relatively small amount (0 to 5%) of the drugs was not adsorbed by the resin and amounts varying from 6 to 40% failed to be desorbed by the eluting solvent. Additional losses occurred during the removal and analysis of TLC spots. Recovery of drugs from aqueous solutions analyzed with the XAD-2 resin were compared to recoveries reported in the literature with other XAD-2 resin methods for the extraction of drugs from urine. Recovery of phenobarbital, morphine, and codeine improved by 4 to 23% while recoveries of amobarbital, pentobarbital, secobarbital, methadone, and meperidine were 4 to 28% less efficient when compared to literature data.

Barbiturates↗
PubMed1998

Antigen detection on resin sections and methods for improving the immunogold labeling by manipulating the resin.

Considering the importance of immunolocalization of cellular substances combined with good ultrastructure and ease of use, this review is focused on the use of resin and the possibilities of manipulating the resin before and after embedding in order to improve the immunolabeling of resin sections for electron microscopy. The qualities of acrylic resins and conventional epoxy resin for immunoelectron microscopy are discussed. Acrylic sections are usually more suited for immunoelectron microscopy than conventional epoxy sections. Different etching procedures (sodium ethoxide or sodium metaperiodate) may be applied to conventional epoxy sections to enhance the yield of immunolabeling. Lately, a method which does not involve any kind of etching has been developed for enhancing the immunogold labeling of epoxy sections up to about 8 times. This method involves increased concentration of accelerator in the epoxy resin mixture when processing the tissue. The ultrastructural preservation of the tissue is important in immunoelectron microscopical procedures, and not only the intensity of the immunolabeling; in this respect no resin may compete with the widely used epoxy resins.

Acrylic Resins↗