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PubMed1998

Study on the surface of resins that burn without residues in the lost-wax procedure.

STATEMENT OF PROBLEM: When compared with waxes and prefabricated components made of dental alloys, processing resins is difficult and often results in a less accurate fit. The exact linear dimension is hard to realize, as the materials required for a dental casting are adjusted to dental waxes, and usually there are no special processing instructions for these resins. PURPOSE: The surface structure of 16 residue-free burning resins was determined to find which could enlarge the range of application for waxes in the dental casting technique. MATERIAL AND METHODS: A total of 480 specimens (30 castings for each of 16 resins) were marked with an individually cut pyramid, which left an impression in the resin. This was distinctly visible in the metal after casting in "the lost form." The surfaces of these 480 specimens were measured in three dimensions with a positioning aid "before casting in resin" and "after casting in metal" by the Perthometer micrometer. All specimens were treated identically by the lost-wax process by using the rotation symmetry of the muffle. The differences in the surface data before casting in resin and after casting in metal characterize the quality of the particular resin. RESULTS: Surface roughness differed between the 16 resins in the range of micrometer. CONCLUSIONS: With the dental casting technique, it is recommended that some resins replace waxes or wax-resin compositions.

Dental Alloys↗
PubMed2005

Sorption and desorption of perchlorate and U(VI) by strong-base anion-exchange resins.

This study investigated the sorption affinity and capacity of six strong-base anion-exchange (SBA) resins for both uranium [U(VI)] and perchlorate (ClO4-) in simulated groundwater containing varying concentrations of sulfate (SO4(2-)). Additionally, desorption of U(VI) from spent resins was studied to separate U(VI) from resins with sorbed ClO4- for waste segregation and minimization. Results indicate that all SBA resins investigated in this study strongly sorb U(VI). The gel-type polyacrylic resin (Purolite A850) showed the highest sorption affinity and capacityfor U(VI) butwasthe least effective in sorbing ClO4-. The presence of SO4(2-) had little impact on the sorption of U(VI) but significantly affected the sorption of ClO4-, particularly on monofunctional SBA resins. A dilute acid wash was found to be effective in desorbing U(VI) but ineffective in desorbing ClO4- from bifunctional resins (Purolite A530E and WBR109). A single wash removed approximately 75% of sorbed U(VI) but only approximately 0.1% of sorbed ClO4- from the bifunctional resins. On the other hand, only 21.4% of sorbed U(VI) but approximately 34% of sorbed ClO4- was desorbed from the Purolite A850 resin. This study concludes that bifunctional resins could be used effectively to treatwater contaminated with ClO4- and traces of U(VI), and dilute acid washes could minimize hazardous wastes by separating sorbed U(VI) from ClO4- prior to the regeneration of the spent resin loaded with ClO4-.

Anion Exchange Resins↗
PubMed2004

Creosote bush (Larrea tridentata) resin increases water demands and reduces energy availability in desert woodrats (Neotoma lepida).

Although many plant secondary compounds are known to have serious consequences for herbivores, the costs of processing them are generally unknown. Two potential costs of ingestion and detoxification of secondary compounds are elevation of the minimum drinking water requirement and excretion of energetically expensive metabolites (i.e., glucuronides) in the urine. To address these impacts, we studied the costs of ingestion of resin from creosote bush (Larrea tridentata) on desert woodrats (Neotoma lepida). The following hypotheses were tested: ingestion of creosote resin by woodrats (1) increases minimum water requirement and (2) reduces energy available by increasing fecal and urinary energy losses. We tested the first hypothesis, by measuring the minimum water requirement of woodrats fed a control diet with and without creosote resin. Drinking water was given in decreasing amounts until woodrats could no longer maintain constant body mass. In two separate experiments, the minimum drinking water requirement of woodrats fed resin was higher than that of controls by 18-30% (about 1-1.7 ml/d). We tested several potential mechanisms of increased water loss associated with the increase in water requirement. The rate of fecal water loss was higher in woodrats consuming resin. Neither urinary water nor evaporative water loss was affected by ingestion of resin. Hypothesis 2 was tested by measuring energy fluxes of woodrats consuming control vs. resin-treated diets. Woodrats on a resin diet had higher urinary energy losses and, thus, metabolized a lower proportion of the dietary energy than did woodrats on control diet. Fecal energy excretion was not affected by resin. The excretion of glucuronic acid represented almost half of the energy lost as a consequence of resin ingestion. The increased water requirement and energy losses of woodrats consuming a diet with resin could have notable ecological consequences.

Animals↗
PubMed2002

Wetting characteristic of ceramic to water and adhesive resin.

STATEMENT OF PROBLEM: Maximum wetting of ceramic by adhesive resin is required to achieve optimal adhesion of the resin to ceramic. It is unknown whether the adhesion of the resin to the ceramic is affected by the surface topography and wetting by water or the adhesive resin. PURPOSE: This study was designed to characterize the effect of surface topography on the wetting of ceramics by water and adhesive resin. MATERIALS AND METHODS: Three materials, a veneering ceramic, Eris (ERV), and 2 core ceramics, Empress 1 core ceramic (E1C) and an experimental core ceramic (EXC), were used. Four surface-roughening procedures were used. They included polishing through 1200-grit SiC paper (P), air abrasion with 50 microm Al(2)O(3) (A), etching with 5% hydrofluoric acid gel (E), and a combination of airborne particle abrasion and etching (A/E). Forty bar specimens (15 x 10 x 1.5 mm) were prepared from each material (N=120). Twelve groups of 10 specimens each were prepared for the 4 surface-roughening procedures. Advancing (theta(A)) and receding (theta(R)) contact angles were measured with a CAHN Dynamic Contact Analyzer, on the basis of the Wilhelmy plate technique, with water and adhesive resin. The work of adhesion (W(A)) by the probing media was calculated by use of advancing contact angle data. The data were analyzed by t testing, analysis of variance, and Duncan's tests (alpha=0.05) to determine the statistical significance of differences in the contact angles between ceramic and water or resin as a function of surface roughening. RESULTS: In general, the mean theta(A) values were higher than the mean theta(R) values except for groups of E or A/E specimens with water used as a probing medium. E and A/E treatments yielded the lowest contact angle values, followed by A and P treatments (P<.001). The E1C exhibited the highest mean contact angles, whereas EXC exhibited the lowest mean contact angle except for the theta(R) with resin. The corresponding values for ERV were between those of E1C and EXC except for theta(R) values with resin. The resin medium yielded higher mean contact angles than the water medium for the same surfaces. W(A) ranged from 62.9 to 145.2 mJ/m(2). CONCLUSIONS: Within the limitations of this study, etching or a combination of air abrasion and etching were comparably effective in increasing the surface area for bonding. The most wettable surface as measured by the resin medium was EXC, followed by ERV and E1C.

Acid Etching, Dental↗
PubMed1996

Accuracy of wax, autopolymerized, and light-polymerized resin pattern materials.

PURPOSE: The marginal fit of MOD inlay and full-crown patterns fabricated from wax, autopolymerized acrylic resin, and two light-polymerized, diacrylate resin pattern materials was compared on standardized dies. MATERIALS AND METHODS: Four pattern materials were studied-two light-polymerized, diacrylate resin materials (Palavit G LC and Triad VLC Burnout Paste), an inlay wax, and an autopolymerized resin (Duralay). Patterns were fabricated using incremental and bulk techniques on stone dies made from addition silicone impressions of American Dental Association MOD and full-crown master dies. Gaps were measured with a measuring microscope in four marginal areas on the master dies at 1 and 24 hours after fabrication. RESULTS: For the MOD inlay patterns, marginal gaps ranged from 7 to 23 microns, and the light-polymerized, diacrylate resins and autopolymerized acrylic resin material had statistically smaller gaps than the inlay wax. For the full-crown patterns, marginal gaps ranged from 10 to 23 microns, with the exception of the autopolymerized acrylic resin prepared by the bulk technique (40 to 46 microns). With the incremental technique, the light-polymerized, diacrylate resins and inlay wax had statistically smaller gaps than the autopolymerized acrylic resin material. Overall, the incremental technique produced equal or smaller marginal gaps than the bulk technique for full-crown patterns. Generally, the patterns measured at 1 hour had smaller marginal gaps than at 24 hours. CONCLUSIONS: When measured on intra- and extracoronal master dies, the light-polymerized, diacrylate resins had equal or better marginal fit, compared with wax or autopolymerized acrylic resin, and were less affected by placement technique and storage. The marginal gaps of all four pattern materials ranged from 7 to 46 microns and are within the range of clinical acceptability.

Acrylic Resins↗
PubMed2000

Biocompatibility of resin-modified filling materials.

Increasing numbers of resin-based dental restorations have been placed over the past decade. During this same period, the public interest in the local and especially systemic adverse effects caused by dental materials has increased significantly. It has been found that each resin-based material releases several components into the oral environment. In particular, the comonomer, triethyleneglycol di-methacrylate (TEGDMA), and the 'hydrophilic' monomer, 2-hydroxy-ethyl-methacrylate (HEMA), are leached out from various composite resins and 'adhesive' materials (e.g., resin-modified glass-ionomer cements [GICs] and dentin adhesives) in considerable amounts during the first 24 hours after polymerization. Numerous unbound resin components may leach into saliva during the initial phase after polymerization, and later, due to degradation or erosion of the resinous restoration. Those substances may be systemically distributed and could potentially cause adverse systemic effects in patients. In addition, absorption of organic substances from unpolymerized material, through unprotected skin, due to manual contact may pose a special risk for dental personnel. This is borne out by the increasing numbers of dental nurses, technicians, and dentists who present with allergic reactions to one or more resin components, like HEMA, glutaraldehyde, ethyleneglycol di-methacrylate (EGDMA), and dibenzoyl peroxide (DPO). However, it must be emphasized that, except for conventional composite resins, data reported on the release of substances from resin-based materials are scarce. There is very little reliable information with respect to the biological interactions between resin components and various tissues. Those interactions may be either protective, like absorption to dentin, or detrimental, e.g., inflammatory reactions of soft tissues. Microbial effects have also been observed which may contribute indirectly to caries and irritation of the pulp. Therefore, it is critical, both for our patients and for the profession, that the biological effects of resin-based filling materials be clarified in the near future.

Animals↗
PubMed1989

[Antibacterial actions of denture base resin on oral bacteria].

Antibacterial action of various denture base resins on thirteen species of bacteria were studied in vitro. Antibacterial effect of 5% tannin-fluoride preparation, 5% tannic acid and 5% chlorhexidine added to resins on these thirteen bacterial species were also investigated using heat-curing denture base resins. Fresh microwave-curing resin and pour-type resin each showed an antibacterial action on one bacterial strain. Fresh self-curing resins had antibacterial actions on several bacterial strains. However, after storage in water at 37 degrees C for one week, antibacterial action of microwave-curing and pour-type resin were diminished and self-curing resins partially lost their antibacterial actions. Denture base resin containing tannin-fluoride preparation or tannic acid showed an antibacterial effect on one bacterial strain. On the other hand, denture base resin containing chlorhexidine had an antibacterial action on eleven bacterial strains. However, color and mechanical properties of the drug-containing resins were not satisfactory.

Bacteria↗
PubMed1978

Marginal leakage and consistency of the composite resin material in etched cavities.

The purpose of the study was to evaluate the degree of adaptation of undiluted and diluted composite resin to etched enamel walls with and without an intermediary resin. Cavities (O = 2 mm) were drilled in extracted teeth and the walls were etched with phosphoric acid. Fillings were made of Concise composite resin, without applying an intermediary resin (1), after applying the resin layer (2), after diluting the mix with one (3) or two (4) drops of catalyst resin but without an intermediary resin, and after diluting the mix and applying the resin layer (5). The fillings were ground flush with the tooth surface and the teeth were cycled thermally between two dye solutions baths. The marginal penetration of the dye was evaluated by measuring the discoloured portion of the margin at different depths using a stereomicroscope. The restorations with an intermediary resin (2 and 5) exhibited significantly less leakage than fillings without the intermediary layer (1, 3 and 4). When no resin layer was applied the dilution of the mix seemed to reduce the leakage compared with undiluted material but the differences were not statistically significant. The results indicate the advantage of using an intermediary resin with etching even when the composite is diluted.

Acid Etching, Dental↗
PubMed1998

The properties of resin supports and their effects on solid-phase organic synthesis.

Solvated resin supports are important carriers for solid-phase organic synthesis in combinatorial chemistry and high-throughput parallel synthesis. The physical properties of resin, resin swelling and dynamic solvation, effects of solvated supports on synthesis, kinetics, site interaction, and product purity are reviewed. Selective solvation of resin alters the local reactivity and accessibility of the bound substrate and the mobility of the entrapped reagent. Resin solvation changes during the course of the reaction when the attached substrate changes its polarity or other physicochemical properties. Selective adsorption determines the reaction kinetics and the action of a phase-transfer catalyst further improves the reaction on resin. Sites interact with each other in 1% DVB polystyrene resins to varying degrees depending on solvent, resin, and reactivity of the pendant groups. Total site isolation seems only achievable by controlling several factors simultaneously such as lower loading and steric hindrance. Through the proper selection of resin and solvent, alternating solvents to accommodate dynamic solvation of the resin, optimization of kinetics when changing solid supports and a careful control of resin impurities, solid-phase organic synthesis can lead to high quality combinatorial libraries.

Chemistry, Pharmaceutical↗
PubMed2006

[The influence of bonding strength of denture soft reline resin by different surface treatments].

PURPOSE: This study evaluated the influence of bonding strength of heat-polymerized denture soft reline resin by 4 different surface treatments bonded to denture base resin. METHODS: Denture base resin (8mm in diameter and 15 mm in length) were fabricated from heat-polymerized acrylic resin (Densply). And heat-polymerized denture soft reline resin disks (Physio liner) were also made (4 mm thick and 10 mm diameter). Two denture base resins were bonded to the denture reline resin disk at the centure on the two sides of the disk. All the specimen were divided into 4 groups (n=10) with 3 different surface treatments: (1) no treatment(control), (2) sandblasted, (3) surface liner application, (4) surface liner application+sandblasted. Bond strength (MPa) was measured by tension bond testing at a 12.7 mm/min speed until the soft reline resin debonded from the base resin. Data were statistically analyzed by SPSS 10.0 software package for ANOVA. RESULTS: The mean bond strengths of group 1, 2, 3, 4 were 3.518, 2.834, 4.077, 3.852MPa respectively. The bonding strength of all the three groups showed significant difference (P<0.0014). The group with surface liner application showed significantly highest bonding strength, while the group with sandblasted showed the lowest bonding strength. CONCLUSIONS: The use of surface liner can significantly improve the bonding strength of heat-polymerized denture soft reline resin to the denture base resin, while the bonding strength decreased after using sandblasting.

Acrylic Resins↗
PubMed1989

Comparative bond strengths of plastic teeth to microwave-curing, heat-curing and 4-META containing denture base resins.

Bond strength of hardened plastic teeth or acrylic resin teeth to microwave-curing, conventional heat-curing and 4-META-containing denture base resins were comparatively investigated in this study. Effects of grinding and monomer coating of the tooth ridge lap were also studied. Bond strength of plastic denture teeth to microwave-curing denture base resin was slightly higher than the other two resins. With all denture base resins used, an increased bond strength was obtained with hardened plastic teeth by treatment of tooth ridge lap but not with acrylic resin teeth. However, scattering of the bond strength was reduced by treatment of tooth ridge lap in acrylic resin teeth specimens. With hardened plastic teeth specimens, fracture in the base resin was increased by monomer coating. With acrylic resin teeth specimens, no specific fracture patterns were demonstrated by treatment of tooth ridge lap. Fracture occurred mostly in the acrylic resin teeth. These results suggest that bond strength of both denture teeth to microwave-curing or 4-META-containing denture base resin was increased or solidified by grinding or monomer coating of tooth ridge lap.

Acrylic Resins↗
PubMed1989

[Correlation between the illumination time and cytotoxicity of light-cured composite resins].

This study was undertaken to compare the relative cytotoxicity of light cured composite resins, and the cytotoxic reduction of light cured composite resins by illumination time by means of in vitro cell culture test. Light cured composite resins (P-30, Silux, Occlusin, Graft LC, Litefil A, Photo Clearfil A, Palfique light and Herculite XR) were filled into glass tubes (4 mm inner dia. x 1 mm high), then illuminated for 0, 10, 20, 30, 40, 50 and 60 seconds through a matrix strip with direct contact ot an Optilux light source (3M), just before testing. Fibroblasts, 2 ml of 1 x 10(5) cells/ml in Eagle's MEM medium supplemented with 10% FCS, penicillin (100 U/ml) and streptomycin (100 micrograms/ml) were evenly seeded on a cover glass in a tissue culture dish and incubated for 24 hours at 37 degrees C in a humidified atmosphere of 5% CO2 in the air. After 24 hours of incubation, the medium was replaced with 2 ml of agar overlay medium consisting of 10% FCS, Eagle's MEM medium and 1.5% agar. Glass tubes (N = 8) filled with the light cured composite resins were placed at the center of the agar, and incubated for 24 hours in 5% CO2 in air at 37 degrees C. After 24 hours of incubation, the cover glass was removed and the cells were fixed in a 10% neutral formalin, then stained with toluidine blue (pH = 9.3) to differentiate the areas of affected and unaffected cells beneath the test specimens. The affected area was quantitatively determined using an image analysis system. The results indicated that there was a high significant reduction in the cytotoxicity of any of the light cured composite resins except Palfique light when light was illuminated. All of the uncured light-cured composite resins revealed a high magnitude of cytotoxicity. However, when composite resin was illuminated, the cytotoxcity of the resin was dramatically reduced, and the longer the light illumination time became, the lesser the cytotoxicity was shown. Palfique light showed a much higher magnitude of cytotoxicity at any light illumination time than any other composite resins. heruclite XR showed less cytotoxicity than Palfique light, however at 60 seconds illumination the cytotoxicity was still shown. The cytotoxicity of composite resins was completely eliminated with illumination times of 50 seconds for P-30, and 60 seconds for Silux. The cytotoxicity of Graft LC, Occlusin and Photo Clearfil A was eliminated with 20 secondlight illumination which showed the least cytotoxicity among the light cured-composite resins tested.(ABSTRACT TRUNCATED AT 400 WORDS)

Cells, Cultured↗
PubMed1989

[New acrylic resins with very low residual monomer].

New experimental acrylic resins were prepared by polymerization of MMA in the presence of vinylidene fluoride/hexafluoropropylene copolymer. The amount of residual monomer in the resins prepared by visible light curing, cold curing, and heat curing, at various polymer/monomer ratios, was measured and compared with the usual MMA/PMMA resin. In the visible light cured resins containing 60 or 70 wt% of the fluoropolymer, the amount of residual monomer was less than 0.1%. In the cold cured resins, the amount of residual monomer was very low: 0.2% and 0.7% for the resins containing 70 and 60 wt% of the polymer, respectively. These values were comparable to the usual heat cured MMA/PMMA resins. In the heat cured resins, the amount of residual monomer was the lowest; less than 0.1%, even in the resin consisting of 50 wt% polymer. Thus, we prepared new acrylic resins with much less residual monomer than the usual MMA/PMMA resins.

Acrylic Resins↗
PubMed1989

[The effect of composition on the mechanical properties of composite resin].

The objective of this investigation was to determine whether the composition of composite resin affects the amount of residual monomers and the strength of resin. Six types of resin composition were designed and 30 composite resin specimens were made in glass mold of 6mm diameter and 3mm height. The residual monomer of each specimen was extracted by 10cc ethanol solution for 1, 2, and 3 days of experiment. UV/Vis spectrophotometer was used to estimate the amount of residual monomer of the specimen, and universal testing machine was used to test the diametral tensile strength of the composite resin. The results were as follow; 1. Composite resins of 1% benzoyl peroxide concentration released the higher level of residual monomers than the resin of 0.8% benzoyl peroxide concentration. 2. t-Butylaminoethylmethacrylate.HF of 17% concentration exhibited the greater level of residual monomer than the other resin monomers. 3. As the concentration of the trimethylolpropane trimethacrylate increased, the amount of Bis-GMA residual monomer increased. 4. Composite resin of 1% benzoyl peroxide concentration showed higher tensile strength than the resin of 0.8% benzoyl peroxide concentration. 5. As the concentration of trimethylolpropane trimethacrylate increased above 50%, the strength of the composite resin decreased.

Chemical Phenomena↗
PubMed1989

[Temporary restoration using light-cured resin].

In spite of various problems involved in chemically cured resin (self-curing resin), e.g., irritability, and heat and shrinkage at polymerization, it has traditionally been the material of choice in the production of temporary restorations. However, light-cured resin, which does not have the disadvantages of chemically cured resin, has recently been developed and applied to clinical treatment. The present study was conducted to examine the clinical application of light-cured resin to temporary crowns. Two types of light-cured resin and one type of chemically cured resin were examined for their mechanical properties. The properties involved in handling and setting, and the methods of producing crowns were also studied. The results were as follows: 1) In the tensile strength test, there was no significant difference between the two types of light-cured resin, i.e., Triad and Unifast LC. The tensile strength of Unifast, a chemically cured resin, was slightly greater than the others, the difference being significant. 2) The Vickers hardness test showed no significant differences between the three types of resin. 3) The mechanical properties of Triad were not influenced by differences in the curing unit (the unit for general oral use or exclusive use) used for polymerization. 4) The test of setting properties revealed that Unifast LC needed longer than Unifast from the 2nd through the 4th clinical stage. In particular, Unifast LC required about 2.5 times the duration needed by Unifast at the 2nd stage in the tray method. 5) The heat generation test showed that the exothermic temperature in Unifast was significantly higher than in the two types of light-cured resin. 6) Heat generation associated with light curing was noted during the use of a light-curing unit for oral use.

Dental Restoration, Temporary↗
PubMed1989

[Disintegration of visible light-cured composite resins caused by long-term water immersion].

The purpose of this study is to clarify a cause of disintegration of composite resins by long-term immersion in distilled water. Three kinds of visible light-cured composite resins (Heliosit, Plurafil Super and Visio Dispers) and one conventional composite resin (Clearfil F II) were prepared as the specimens with a 20 mm diameter and 1 mm thickness. These specimens were immersed in distilled water at 37 +/- 1 degree C for 3 years. These specimens were analysed and observed by a comprehensive multi analyzer and scanning electron microscope. The other hand residues in distilled water were analysed by infrared (IR) and nuclear magnetic resonance (NMR) spectrometers. The surface layer of all four composite resins showed signs of disintegration. The composite resins with abundant dissolved substances had disintegrated markedly, and such disintegration occurred deep inside the specimens. In IR and 1H-NMR spectra of dissolved substances, two visible light-cured composite resins (Heliosit and Plurafil Super) could be detected unreacted monomers, but one visible light-cured composite resin (Visio Dispers) and one conventional composite resin (Clearfil F II) could not be detected them. In 1H-NMR spectra of dissolved substances of all four composite resins, new signals not composed originally were observed. The progress of disintegration were demonstrated clearly. The dissolved substances were shown as the disintegrated substance between resin matrixs and silane coupling agents. It is suggested that the disintegration of composite resins by long-term water immersion is derived from hydrolysis.

Composite Resins↗
PubMed1981

[Studies on the dynamic durability of dental restorative materials. Part 4. Materials evaluation of initial and fatigue specimen for composite resins by acoustic emission method].

Present study is directed towards development for a method of materials evaluation of the static and dynamic properties for dental restorative materials and nondestructive inspection of the dental restorations in oral cavity by acoustic emission (AE) method. AE characteristics and deformation-fracture behavior of hour commercial composite resins under three points bending test are examined in order to evaluate initial and fatigue specimen for conventional and microfilled composite resins. Experimental results obtained are as follows: (1) Deformation-fracture behavior of conventional and microfilled composite resins exhibits different mode, corresponding to relatively brittle and ductile fracture behavior, respectively. Therefore, the primary sources of AE for conventional and microfilled composite resins under bending test are related mainly to the nucleation and propagation of cracks and plastic deformation, respectively. (2) In conventional composite resins under bending test, the burst type AE signal of higher amplitude and shorter decay time and more many AE total counts tend to be observed. In microfilled composite resins under bending test, the burst type AE signal of lower amplitude and longer decay time and more a few total counts tend to be observed. (3) Composite resins, particularly conventional composite resins under unload and repeated bending load are indicative of different AE characteristics. Accordingly, application of AE method for composite resins offers a method to evaluate the static and dynamic strength of composite resins. (4) In conventional composite resins under bending test, as characteristic AE are observed in a few stress regions before fracture, it may be possible to monitor nondestructively the restorations in oral cavity by using AE method.

Composite Resins↗
PubMed1977

Allergenicity of epoxy resins in the guinea pig.

The sensitizing capacity of epoxy resins of diglycidylether-Bisphenol A type was investigated using the "guinea pig maximization test". One isolated resin had a molecular weight (MW) of 340, which is the lowest among this type of epoxy resin. The other resins were mixtures with different MWs. Their distribution is not known, but only their average MW. The low molecular weight resin sensitized all of the animals and can be classified as an extreme allergen. The sensitizing capacity decreased in inverse proportion to the increase in the average MW of the resin mixtures. The cross-testing also indicated that the resin mixtures with higher average MW contained enough of the low MW resin (MW 340) to render this resin a sensitizer. Bisphenol A did not sensitize the animals at all but epichlorhydrin sensitized 60%. It is evident that in order to formulate hypoallergenic epoxy resins it will be necessary to achieve sensitization of animals with isolated resins of varying molecular weight.

Allergens↗