Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RESINS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed1998

The role of maleic anhydride in adhesive resin cements.

The adherence of resin cements depends upon, among other factors, the polar interactions across the interface: resin cement/restorative material. The polar interactions may be augmented by inclusion of polar additives such as maleic anhydride to the cement monomer. However, maleic anhydride is slowly converted to maleic acid when exposed to an aqueous environment. This may affect mechanical properties of such a cement in a negative way. It was the aim of the present investigation to analyze the role of maleic anhydride dissolved in the monomer of resin cements. The resin cement monomers used were common methacrylates, to which maleic anhydride in amounts of up to 30 mol% was added. Polymerization initiators were included to make the materials dual curing. Finally, the preparations were mixed with silanated fillers. The adherence energy of the cements bonded to a chromium-cobalt alloy was assessed by means of the double cantilever beam test. The strength and stiffness of the resin cements were recorded at base line and after two months storage in water. The initial adherence energy increased by a factor of about two as a result of addition of maleic anhydride. However, resin cements containing maleic anhydride suffered significant reductions in long-term adherence, strength and stiffness. These reductions were particularly pronounced in non-irradiated specimens. The use of resin cements containing maleic anhydride is not a viable means of conveying adhesiveness to resin cements.

Adhesiveness↗
PubMed2004

Repair bond strength of restorative resin composite applied to fiber-reinforced composite substrate.

Delamination or fracture of composite veneers can occur as a result of improper design of the fiber-reinforced composite (FRC) framework. This in vitro study tested the repair bond strength of restorative composite to aged FRC. The substrate was multiphase polymer matrix FRC (everStick) aged by boiling for 8 h and storing at 37 degrees C in water for 6 weeks. The aged substrate surfaces were wet-ground flat with 1200-grit silicon carbide paper and subjected randomly to 5 different surface treatments: 1) An adhesion primer (Composite Activator) and resin (CA), 2) Silane (EspeSil) and resin (SIL-MP), 3) Silane, adhesive primer, and resin (Clearfil Repair) (CF), 4) Air particle-abrading (CoJet), silane, and resin (CJ-SIL-MP), 5) Resin (Scotchbond Multipurpose Resin) only as control (MP). Restorative composite resin (Z250) was added to the substrate in 2 mm layer increments and light-cured. Subsequently, every surface treatment group was divided into 2 subgroups of 12 specimens each. The specimens were either 48 h water-stored or thermocycled (6000 x 5-55 degrees C). The shear bond strengths of composite resin to FRC were measured at a crosshead speed of 1.0 mm/min. The data were analyzed by ANOVA for factors 'treatment type' and 'storage condition'; Tukey's post-hoc tests and Weibull analysis were performed. ANOVA showed a significant difference as a function of surface treatment (P<0.05) and storage condition (P<0.05). The CJ-SIL-MP group showed highest bond strength and Weibull modulus after thermocycling. Repair of multiphase polymer matrix FRC may show reliable bond strength when silane treatment is used along with air-particle abrading.

Air Abrasion, Dental↗
PubMed2006

Detection and classification of composite resins in incinerated teeth for forensic purposes.

The great demand for esthetic restorations has resulted in placement of large numbers of composite resin fillings. The popularity of these materials is reflected in the quantity and variety of resin brands currently on the market. The ability to distinguish resin brands can aid in positive identification of burn victims, assuming that appropriate dental records exist. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) was used to characterize the structure and composition of 10 modern resins. The structure of each resin was unique to manufacturer, and elemental analysis allowed separation into distinct groups. These 10 resins were also placed in extracted teeth and incinerated at 900 degrees C for 30 min, simulating near cremation conditions. The resins were identifiable by SEM/EDS after incineration, and the elemental composition remained almost unchanged. The data produced are immediately useful for resin identification in forensics, and comparative analysis can be readily performed using standard equipment. This work represents the initial stage of database generation.

Acrylic Resins↗
PubMed1977

Working time and strength in relation to consistency of composite resins.

Composite resin pastes can be made more fluid for injection purposes by adding small amounts of enamel bond resin before mixing. The aim of this work was to study the influence of the added resin on the working time and on the early and final strength of the composite. The pastes of two different brands diluted with their respective resins and the working time of the mix was determined by measuring the time during which it was possible to squeeze the material from a Centrix syringe. The results revealed that adding universal resin reduced the working time of both brands. The catalyst resin increased the working time of Adaptic but with Concise the amount of the catalyst paste had also to be increased to gain more working time. Adding catalyst resin did not affect the early strength or the strength after 24 h. Furthermore, it was observed that adding resin reduced the amount of porosities in the composite.

Composite Resins↗
PubMed1986

A clinical comparison of three anterior restorative resins at 3 years.

An in vivo comparison was made of three different types of restorative resins: a conventional composite resin, a chemically cured microfilled resin, and a small-particle, glass-filled, visible light-cured composite resin. Twenty-eight sets of three restorations were placed 20 patients and examined using the Ryge rating system. All resins performed well and were not significantly different from one another at 1 year. After 3 years, all materials were considered satisfactory, but the conventional composite resins had significantly more surface roughness than did the other resins. Each of the resin materials also declined in color match after 3 years.

Acrylic Resins↗
PubMed1979

[8-Quinolinol-5-sulfonic acid-loaded resin as a preconcentrating agent in the neutron activation analysis of the chalcophile elements (author's transl)].

A chelating agent-loaded resin consisting of 8-quinolinol-5-sulfonic acid and an anion-exchange resin (HOx-resin) was prepared in order to concentrate trace chalcophile elements in natural water samples selectively before neutron activation analysis. The exchange capacity of the Diaion SA No. 100 for the reagent (1.8 meq . g-1 resin) corresponds approximately to that for chloride ion (1.83 meq . g-1 resin), indicating that 8-quinolinol-5-sulfonic acid is adsorbed quantitatively on the exchange site of the resin through the sulfonate anion in the reagent. The basic conditions for the adsorption of the metal ions on the resin were investigated by employing the column method. The nitrate concentration and the pH of the sample solution affect the adsorption behavior of metal ions. Several solutions containing metal ions with varying pH or varying nitrate concentration were applied to the resin column (35 mm x 7 mm phi) with a flow rate of 2.0 cm3 . min-1. As a result, the optimum conditions for the quantitative adsorption of copper(II), zinc(II), cadmium(II), cobalt(II), nickel(II) and manganese(II) were as follows: NO3- less than 0.01 mol . dm-3 pH greater than 4.6. Furthermore, the feasibility of the above conditions as well as quantitative adsorption of the chalcophile elements was confirmed through the neutron activation analysis of the synthesized metal solutions.

Activation Analysis↗
PubMed2001

Does single versus stepped curing of composite resins affect their shear bond strength?

BACKGROUND: Shrinkage occurs during polymerization of all resin composites, affecting not only the physical properties of the composites but also the marginal integrity of the restoration. Stepped photo-polymerization, in contrast to single-cure photo-polymerization, is said to minimize this shrinkage. The thickness of the increments of resin composite being cured may also be a factor in final shear bond strength. This study compared the shear bond strength resulting from these two curing methods with resin composites of various thicknesses. METHODS: Resin composite in increments of 1.5, 3 and 4.5 mm thickness, cured by stepped or single-cure photo-polymerization, was bonded to human third molar dentin with either the Scotchbond Multipurpose adhesive system or the Singlebond adhesive system. Each experimental group consisted of 12 specimens. After 7 days of storage in water, shear bond strength was tested to failure, and the mode of failure was recorded. RESULTS: The thickness of the resin composite and the method of curing had no significant effect on shear bond strength for bonds mediated by Scotchbond Multipurpose adhesive, but significantly lower shear bond strength was recorded for bonds mediated by Singlebond adhesive for resin composite 4.5 mm in thickness. With thicker resin composite, there was a tendency toward a greater proportion of adhesive cohesive bond failures. CLINICAL SIGNIFICANCE: The stepped photo-polymerization system of curing appears to offer no advantages over single-cure photo-polymerization, except that the former reportedly improves marginal adaptation and reduces marginal leakage. These results suggest that increments of resin composite to be cured by either method should be no thicker than 2 mm, particularly when the bond is mediated by a single-bottle adhesive.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2001

Fracture toughness of posterior resin composites.

OBJECTIVES: The purpose of this study was to evaluate and compare the resistance to crack propagation, as measured by the fracture toughness, of some packable posterior resin composites with other posterior resin composite materials. METHOD AND MATERIALS: Fracture toughness determinations were made for the 5 packable and the other posterior resin composites using 3-point flexure of beams with a standardized central single-edge notch. Ten beams of each material were tested on an Instron test machine. The maximum loads were determined, from which the fracture toughness values (KIC) were calculated. The data were analyzed statistically using ANOVA and t tests. RESULTS: The resin composites tested demonstrated a range of KIC values. The materials were separated according to the mean KIC values into 5 groups that were statistically different. While 2 packable resin composites had KIC values that were among the highest, the other packables were substantially lower than nonpackables. The intermediate value group consisted of 3 of the conventional posterior resin composites. CONCLUSION: There was a very weak correlation between fracture toughness and reported volume concentration of particulate reinforcing elements. The posterior resin composites tested exhibited a spectrum of KIC values. The packable resin composites were distributed along this spectrum, with 2 products exhibiting high potential for resistance to crack propagation.

Acrylic Resins↗
PubMedDate not supplied

Temperature rise during adhesive and resin composite polymerization with various light curing sources.

This study evaluated the temperature rise in two different adhesive (Clearfil SE Bond [CSEB] and EBS-Multi [EBSM]) and composite systems (Clearfil AP-X [CAPX,] Pertac II [PII]) by the same manufacturer when illuminated by four different light sources: Light-emitting diode (LED), Plasma arc curing (PAC), high intensity quartz tungsten halogen (HQTH) and quartz tungsten halogen (QTH). Forty dentin disks were prepared from extracted premolars. These dentin disks were placed in apparatus developed to measure temperature rise. Temperature rise during photopolymerization of adhesive resin and resin composite was then measured. The mean values of temperature increases for adhesive and resin composites did not differ significantly (p=0.769). The highest temperature rise was observed during photopolymerization of EBSM with PAC (5.16 degrees C) and HQTH (4.28 degrees C), respectively. Temperature rise values produced by QTH (1.27 degrees C - 2.83 degrees C for adhesive resin; 1.86 degrees C - 2.85 degrees C for resin composite) for both adhesive and resin composites were significantly lower than those induced by PAC and HQTH (p<0.05). However, these values were significantly higher than those produced by LED (1.16 degrees C - 2.08 degrees C for adhesive resin; 1.13 degrees C - 2.59 degrees C for resin composite). Light sources with high energy output (PAC and HQTH) caused significantly higher temperature rise than sources with low energy output (QTH and LED). However, in this study, no temperature rises beneath 1-mm dentin disk exceed the critical 5.6 degrees C value for pulpal health.

Analysis of Variance↗
PubMed1991

Effects of warm air-drying and spreading on resin bonding.

The purpose of this study was to compare the effect on resin-to-enamel bonding produced by warm air from a hair dryer, and to correlate changes in resin bond strength with resin tag structure. Herculite-XR resin composite and Bondlite bonding resin were used. The three technique variables were the type of air used for drying, air dryer distance, and drying and spreading time. Control samples were dried and the bonding resin spread with a dental air syringe, whereas warm air from a hair dryer was used on the experimental samples. The bond strength (MPa) was determined in shear at a crosshead speed of 1 mm/min. Following bond strength evaluation, the teeth were immersed in 10% HCl for enamel dissolution and the resin tag structure was examined with the SEM. ANOVA analyses of shear bond strengths were performed. Warm air-drying and spreading for 15 seconds at 6 cm and 5 seconds at 6 cm respectively, produced statistically greater shear bond strengths (x = 20.4 +/- 4.4 MPa, P less than 0.05). The other drying time/distance combinations, including the control (x = 14.4 +/- 3.3 MPa), were not statistically different. Differences in resin tag structure were qualitatively evident under the SEM, with sharp tags produced by the warm air-drying and spreading techniques, compared to the blunt tags created by syringe air-drying and spreading. Warm air-drying and spreading significantly improved the bond strength. No apparent correlation exists between bond strength and tag length.

Air↗
PubMed1997

Reinforcement of acrylic resins for provisional fixed restorations. Part II: Changes in mechanical properties as a function of time and physical properties.

In Part I, it was found that (i) 2 vol.% admixture of reinforcing elements in PMMA (Jet) resin matrix had a significant beneficial effects on the mechanical properties, and (ii) among these, zirconia exhibited the greatest improvements in modulus of elasticity, transverse strength, toughness, and hardness number. Using the best combination (i.e., PMMA resin matrix and 2 vol.% ZrO2), exothermic temperature raise and polymerization shrinkage were further investigated. Deterioration in mechanical properties due to prolonged water sorption were also studied for 5 weeks. The following can be concluded: (1) By increasing liquid/powder ratio for PMMA control samples, the peak temperature occurrence was retarded by 3 min and raised by 8 degrees C. (2) The effect of admixed oxide particles to PMMA resin matrix or the heat generated during polymerization was not significant. (3) The polymerization volumetric shrinkage was influenced by the a mixture of particles, with increases as large as 0.9% (or 0.3% in linear shrinkage). (4) PMMA resin admixed with 2 vol.% of zirconia particles showed a continuous weight gain due to water sorption, mechanical properties appears to be increasing up to 1-week sorption, followed by rapid drop of all properties. (5) Autopolymerizing acrylic resins are a resin-resin composite material of pre-polymerized beads embedded in a newly formed acrylic matrix. The main fracture modality appears to occur through the matrix and at the interface, although some trans-beads fractures were identified. (6) It was suggested that incorporating certain type of oxide particles into the pre-polymerized beads would provide stronger resin matrix.

Acrylic Resins↗
PubMed2004

Performance of three resin-based materials for treating uranium-contaminated groundwater within a PRB.

Three materials that are designed to treat uranium-contaminated water were investigated. These are a cation exchange resin, IRN 77; an anion exchange resin, Varion AP; and a recently developed material called PANSIL (quartz sand coated with 2% amidoxime resin by weight). The reaction rate, capacity, and effective pH range of the three materials are reported. The capacity and conditional distribution coefficient in neutral, uranyl-contaminated synthetic groundwater containing carbonate are also reported. The suitability of each material for treating uranium-contaminated groundwater using a permeable reactive barrier (PRB) approach is then discussed. All three materials react rapidly in the pH range 5-7, reaching equilibrium in less than 4h at approximately 23 degrees C. The unconditioned cation exchange resin removed 8 g UO2 2+ per kg of resin from neutral synthetic groundwater containing 30 mg/l of UO2 2+, but a lower capacity is anticipated in groundwater with either higher ionic strength or lower UO2 2 concentrations. It operates by first acidifying the solution, then sorbing UO2 2, and can release UO2 2 when its buffering capacity has been exhausted. The anion exchange resin is very effective at removing anionic uranyl carbonate species from solutions with a pH above 5, with good specificity. Up to 50 g/kg of uranium is removed from contaminated groundwater at neutral pH. PANSIL is effective at sequestering cationic and neutral uranyl species from solutions in the pH range 4.5-7.5, with very good specificity. The capacity of PANSIL is pH-dependent, increasing from about 0.4 g/kg at pH 4.5, to about 1 g/kg at pH 6, and 1.5 g/kg around pH 7.5. In neutral groundwater containing carbonate, both the anion exchange resin and PANSIL exhibit conditional distribution coefficients exceeding 1470 ml/g, which is about an order of magnitude higher than comparable reactive barrier materials reported in the literature.

Adsorption↗
PubMed1996

Influence of dentin conditioning on bond strength of light-cured ionomer restorative materials and polyacid-modified composite resins.

The purpose of the study was to evaluate the dentin bond strength of restorative materials containing both glass ionomer and composite resin components. Three resin-modified glass ionomer restorative materials (Fuji II LC, Photac-Fil, Vitremer), three polyacid-modified composite resins (Dyract, Ionosit Fil, VariGlass VLC), a hybrid composite (blend-a-lux) and a chemical-cured glass ionomer cement (ChemFil Superior) were investigated for dentin tensile bond strength with and without conditioning of the tooth surfaces. For each material, tensile bond strength was determined using five conditioned and five unconditioned bovine tooth specimens. Conditioning of the specimens was performed according to the manufacturers' instructions. The tensile bond strength was tested with a universal testing machine. Statistical analysis was performed with analysis of variance, the Scheffe's-test and the Student's t-test. All materials showed higher adhesion to conditioned dentin than to unconditioned specimens. Except for Photac-Fil, the bond strength to conditioned dentin of all resin-modified glass ionomer restorative materials and polyacid-modified composite resins was higher as compared to the chemical-cured glass ionomer and the hybrid composite. However, these differences were not statistically significant. All polyacid-modified composite resins resulted in higher bond strengths to conditioned dentin as compared to the resin-modified glass ionomer restorative materials. These differences were statistically significant only for VariGlass VLC as compared to Photac-Fil. In order to improve adhesion of the tested materials to dentin it is highly recommended to follow the manufacturers' instructions concerning dentin conditioning.

Acrylic Resins↗
PubMed1997

Epoxy-embedded versus nonembedded TEM examination of the resin-dentin interface.

When transmission electron microscopy (TEM) is used to evaluate resin-dentin interface specimens for completeness of hybridization, the epoxy resin embedding medium that normally facilitates ultrathin sectioning may produce a secondary or artifactual hybrid layer. This secondary hybrid layer, composed of epoxy resin rather than adhesive resin, may fill the pores that remain as evidence of incomplete resin infiltration, obscuring the fact that they ever existed. In this study, resin-dentin interfaces produced by two dentin adhesive systems, Optibond (OPTI, Kerr) and Scotchbond Multi-Purpose (SBMP, 3M), were comparatively investigated by TEM in epoxy-embedded and nonembedded nondemineralized sections. The hypothesis advanced was that no difference in ultramorphology of the hybrid layer would result from either specimen preparation method. The two adhesive systems were applied to four mid-coronal dentin disks per manufacturer's instructions. One half of each sample was processed following common procedures for TEM sample preparation with epoxy embedding, whereas the other half was not embedded but instead immersed in hexamethyldisilazane (HMDS), dried and mounted so that it protruded from a base of cold-cure acrylic resin. Each sample was then sectioned using a diamond knife in an ultramicrotome. With either means of preparation, a hybrid layer with a relatively uniform electron density and a loose collagen fibril arrangement with electron lucent interfibrillar channels was formed by OPTI. At the base of the hybrid layer, collagen fibrils were anchored in the underlying unaffected dentin, and no microporosities or gaps were observed. Similarly, whether SBMP was embedded or nonembedded, it was found to have a hybrid layer of variable electron density and an electron dense phase localized at the surface of the hybrid layer. No porosities were evident at the base of the hybrid layer. Thus, with either of the two adhesive systems, no ultrastructural difference in hybrid layer formation was observed between epoxy-embedded and nonembedded sections, and no direct evidence of ineffective resin-infiltration of the demineralized collagen scaffold was found.

Acid Etching, Dental↗
PubMed1999

Cytotoxicity tests of in situ polymerized resins: methodological comparisons and introduction of a tissue culture insert as a testing device.

The in vitro cytotoxic potential of six commonly used methacrylate polymers was evaluated using human oral fibroblast cultures with different cell-material contact systems. A tissue culture insert was introduced to test resin-released components. Both acute and delayed cytotoxic effects of resin were quantified by cellular enzymatic and DNA synthetic activities of fibroblasts over a 6-day exposure period. Resin toxicity was material-dependent. Statistical analysis showed that the experimental conditions significantly contributed to the overall toxicity and the cytotoxicity pattern for a given material. DNA synthesis activity of human oral fibroblasts assayed by 3H-thymidine incorporation was more sensitive to resins than cellular enzyme activity, as determined by tetrazolium bromide reduction. However, extended exposure increased the cytotoxicity of all resins, as measured by tetrazolium bromide reduction, which seemed to be a better indicator of the development of resin toxicity than 3H-thymidine incorporation. Removal of the oxygen inhibition layer on resin specimens partially enhanced cell viability, indicating that this surface layer together with other unknown factors contributed to resin toxicity.

Cell Survival↗
PubMed2004

ULTRAMINE: a high-capacity polyethylene-imine-based polymer and its application as a scavenger resin.

The synthesis of a novel high-loading polyethylene-imine resin (ULTRAMINE) is described, and its application as a scavenger resin in various acylation reactions is demonstrated. The inverse suspension polymerization technique was used for the synthesis of well-defined spherical polymer beads. Polymer beads with different cross-linking densities were synthesized according to the degree of acryloylation of the polyethylene-imine polymer. The resin was characterized by various spectroscopic techniques. The size, shape, and morphological features of the resin were demonstrated by microscopy. The resin showed excellent swelling properties in both polar and nonpolar solvents. The chemical stability of the resin in various reagents and solvents was investigated and monitored by IR spectroscopy. The mechanical stability of the beads was determined by a single-bead compressive experiment. The ULTRAMINE beads can be used as an excellent scavenger for excess acylating reagent, as demonstrated for a variety of reactions. ULTRAMINE-red resin was derived from ULTRAMINE through exhaustive reduction of the amide carbonyl groups to yield an all-amine resin.

Imines↗
PubMed1993

In vivo biocompatibility of an acrylic, fluoride-releasing, anion-exchange resin.

This study evaluated the biocompatibility of an unfilled, fluoride-releasing acrylic resin by subcutaneous implantation in guinea pigs. The experimental fluoride resin was compared to a nonfluoride, dental pit and fissure sealant (DELTON) of similar composition. Thirty-four male albino guinea pigs received four Teflon tubes each, implanted in the dorsal area. The tubes were open at both ends, three contained the experimental fluoride resin and one held the nonfluoride resin. The tubes and surrounding tissue were excised in 1-2 cm blocks, by necropsy, at 14 and 84 days. Histological evaluation showed that inflammatory response was none-to-slight at 14 days for 95% of the fluoride and 100% of the nonfluoride specimens. Five percent of the fluoride specimens produced a moderate tissue response. At 84 days, inflammatory response was none-to-slight for 82.5% of the fluoride and 61.5% of the commercial nonfluoride specimens, while 17.5% of the fluoride and 38.5% of the nonfluoride specimens produced moderate tissue responses. Chi-squared analysis and Fisher's Exact test revealed no statistically significant difference (p less than or equal to 0.05) in tissue response between the two resins at either 14 or 84 days. Hence it is concluded that the experimental, fluoride-releasing resin produces a very mild subcutaneous tissue response and that its biocompatibility is comparable to that of a widely used nonfluoride dental resin. It can, therefore, be considered as having a high potential for biological safety as a dental restorative resin or adhesive, or for other biomedical applications.

Acrylic Resins↗
PubMed1991

Interactions of proteins in human plasma with modified polystyrene resins.

Investigations are reported on the composition of protein layers adsorbed from plasma to various modified polystyrene resins. As well as polystyrene itself, polystyrene bearing sulfonate groups in the benzene rings, and polystyrene sulfonate in which the sulfonate groups were converted to amino acid sulfamide, were investigated. Some of these resins were shown in previous work to have anticoagulant properties. To study the adsorption of proteins from plasma, the resins were exposed to citrate anticoagulated human plasma for 3 h. Adsorbed proteins were then eluted sequentially by 1M Tris buffer and 4% SDS solution, and examined by SDS-PAGE. The gel patterns were similar on all resins except polystyrene. From the MWs of the gel bands, the major protein component appeared to be fibrinogen. Smaller amounts of plasminogen, transferrin, albumin, and IgG were also present. In addition, Ouchterlony immunoassay of the eluates from one resin gave positive identification of complement C3, fibronectin, IgG, and IgM. Many other minor gel bands remain unidentified. A consistent finding for all resins was the presence of plasmin-type fibrinogen degradation products though the amounts varied with resin type. It is concluded from this (and from experiments showing FDP formation when fibrinogen was absorbed to the resins, from buffer containing a trace of plasminogen) that the functional groups in these materials promote the adsorption of plasminogen and its activation to a plasmin-like molecule. It appears from the substantial quantities of fibrinogen adsorbed to these materials after 3 h exposure to plasma that the Vroman effect (giving transient adsorption of fibrinogen) is not operative on these materials. It is hypothesized that specific interactions occur between fibrinogen and sulfonate groups.

Adsorption↗