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PubMed1989

[Physical and mechanical properties of the thermosetting resin for crown and bridge cured by micro-wave heating].

A heating method using micro-waves was utilized to obtain strong thermosetting resin for crown and bridge. The physical and mechanical properties of the thermosetting resin were examined. The resin was cured in a shorter time by the micro-waves heating method than by the conventional heat curing method and the working time was reduced markedly. The base resins of the thermosetting resin for crown and bridge for the micro-waves heating method were 2 PA and diluent 3 G. A compounding volume of 30 wt% for diluent 3 G was considered good the results of compressive strength, bending strength and diametral tensile strength. Grams of 200-230 of the filler compounded to the base resins of 2 PA-3 G system provided optimal compressive strength, bending strength and diametral tensile strength. A filler gram of 230 provided optimal hardness and curing shrinkage rate, the coefficient of thermal expansion became smaller with the increase of the compounding volume of the filler. The trial thermosetting resin for crown and bridge formed by the micro-waves heating method was not inferior to the conventional resin by the heat curing method or the light curing method.

Crowns↗
PubMedDate not supplied

Scanning microscopy of resin infiltration patterns in acid-etched incisor enamel.

Previous studies have described the surface morphologic characteristics of acid-etched enamel. The purpose of this investigation was to examine the patterns of resin infiltration into the etched enamel. Fourteen, human, incisor teeth, extracted because of advanced periodontal disease, were etched on the labial surfaces for 60 seconds with 37% phosphoric acid, washed in tap water, and then air-dried. A self-cured enamel resin was applied to the etched labial surface and supported with epoxy. The teeth were dissolved in formic acid. The resin remnants were cleaned in water, dried, mounted on specimen stubs, coated with sputtered gold, and examined in a Scanning electron microscope (SEM). Resin infiltration patterns were photographed in the SEM at a magnification of 400 in 0.125-mm2 areas of the incisal, middle, and gingival thirds of each labial surface. Resin infiltration patterns were scored according to the correspondence with the rod-core, rod-periphery, and irregular acid-etch patterns seen in enamel. The distribution of resin infiltration patterns was as follows: rod-core, 9.7%; rod-periphery, 40.5%; and irregular, 49.7%. The values were averaged over all the surface areas. Infiltration patterns into the etched enamel exhibited deep interperikymata resin penetration. Subsurface channeling of resin was responsible for the pattern seen in irregular etch and was the most common form of infiltration in the gingival region. Subsurface channeling may be related to the development of micropores observed in incipient carious lesions. Deep monomer penetration and channeling may be important factors in mechanical attachment.

Acid Etching, Dental↗
PubMed1986

Safety and efficacy of long-term diet and diet plus bile acid-binding resin cholesterol-lowering therapy in 73 children heterozygous for familial hypercholesterolemia.

Our specific aim was to examine the efficacy and safety of long-term cholesterol-lowering diet and bile acid-binding resin therapy in 73 children heterozygous for familial hypercholesterolemia (FH). We prospectively followed accretion of height and weight in 40 FH children for 5.8 years on diet alone and in 33 FH children for 4.3 years on diet and bile acid-binding resins (8 to 20 g/d). In 67 of these 73 children, sequential data on plasma cholesterol lowering was obtained, including 32 children on diet plus bile acid-binding resins and 35 on diet alone. For all 73 children, median age, sex, and race-specific percentiles for height and weight at entry were 50 and 50, respectively, and 5.7 years later, were unchanged at 50 and 50. Initial and final percentiles for height (r = .76, P less than .001) and weight (r = .70, P less than .001) were closely correlated. Percentile distributions for height and weight at entry into the study did not differ from those at the end of follow-up (P greater than .1), in both the 40 FH children on diet alone and the 33 on diet plus bile acid-binding resins. Tracking of height and weight did not differ in the 40 children on diet alone v the 33 on diet plus bile acid-binding resins (P greater than .1). During 6 years of follow-up there were no significant differences in the percentage of serial, postbaseline measurements for height which were either less than or greater than or equal to baseline percentiles, comparing 40 FH children on diet alone, 33 FH children on diet plus resin, and 39 normal children (on ad libitum diet). FH children on diet or plus resin had a smaller percentage of weight measurements equal to or more than baseline percentiles than normals on follow-up (P less than .01), probably reflecting restriction of total fat intake to less than 35% of calories. On diet alone, 32 FH children had total plasma cholesterol of 307 +/- 8 mg/dL (mean +/- SE); bile acid-binding resins were added to diet in these children at an average age of 11.5 years, with this regimen maintained for 4.6 +/- 0.4 years, leading to a mean reduction in total plasma cholesterol of 12.5% +/- 2% beyond the effects of diet alone (P less than .01).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1981

[Mechanical properties of microfilled composite resins (author's transl)].

The various mechanical properties of seven microfilled composite resins were evaluated, comparing with two conventional composite resins. The following results were obtained. 1) Though microfilled composite resins were more excellent than conventional ones on surface roughness after polishing or brushing, but they were inferior to conventional ones on the resistance to brushing abrasion. 2) Tensile, compressive and bending strength were dependent on inorganic filler content and properties of matrix resin. Particularly, their mechanical properties in the wet condition were strongly influenced by whether matrix resin was hydrophilic or hydrophobic. Compared with conventional composite resins, microfilled ones contained 30 to 40 wt% of filler had lower values of tensile and bending strength, and near values of compressive strength. While, microfilled ones contained 50 to 60 wt% of filler had higher values of compressive strength, and near values of tensile and bending strength, compared to conventional ones. 3) Modulus of elasticity and hardness were mainly dependent on inorganic filler content. Moduli of elasticity of microfilled composite resins were about 25 to 33% of them of conventional ones, and hardnesses of microfilled ones were approximately 50% of them of conventional ones except some materials. Hardnesses of microfilled composite resins with 50 to 60 wt% of filler were similar to them of conventional ones.

Chemical Phenomena↗
PubMed1981

[Dimensional stabilities of microfilled composite resins (author's transl)].

Thermal expansion, expansion by water sorption, water sorption and solubility to water, which will influence to the marginal closure of cavities restored, were evaluated in seven microfilled composite resins, comparing with two conventional composite resins. The following results were obtained. 1) Coefficients of linear thermal expansion of microfilled composite resins were 41 to 84 x 10(-6)/degrees C in the dry condition and 57 to 93 x 10(-6)/degrees C in the wet condition. Those values were about 2 to 3 times those of conventional composite resin, and about 6 to 8 times that of teeth. 2) Linear expansion by water sorption was highly correlated to water sorption. Microfilled composite resins had higher values of liner expansion by water sorption compared to conventional ones. 3) Generally, water sorption of microfilled composite resins were higher than those of conventional ones. After 7 days, they were about 0.4 to 1.9 mg/cm2. Values of microfilled ones which contained larger amount of filler or was composed of more hydrophobic matrix resin, however, were lower than others. 4) Solubilities to water of microfilled composite resins also were higher than those of conventional ones. Particularly, microfilled ones which were used organic composite filler and UDMA monomer as base material and photopolymerized had relatively higher values.

Absorption↗
PubMedDate not supplied

Biocompatibility of visible light-polymerized denture base resins.

The biocompatibility of three commercial formulations of visible light-polymerized denture base resins was studied to determine its effects on the RNA and DNA synthesis of oral epithelial cells in vitro. Isotope incorporation into RNA or DNA was measured after 24 hours of incubation with isotope and 48 hours of exposure to resin. The resins were shown to significantly inhibit the synthesis of both nucleotides as compared to a heat-processed resin control. Increasing the polymerization time can mitigate the toxicity of some of the resins. The air barrier coatings used to prevent oxygen inhibition of polymerization increased the toxic effects of two resins and decreased that of one of the materials. These investigations suggest that visible light-polymerized denture resins may impair the replication of oral epithelial cells. DNA synthesis is more sensitive to the toxic effects of the materials, which may relate to the ability to cause mucosal pathology. The cytotoxic effects may relate to the presence of unpolymerized resin constituents or polymerization by-products.

Acrylic Resins↗
PubMed1993

Bending rigidity of composite resin coating clasps.

The purpose of this study is to examine the bending profiles of composite resin coating cast clasps. The cobalt-chromium alloy cast clasps were made using tapered wax pattern. Silane coupling method (Silicoater MD, Kulzer Co.) was used to attach composite resin to metal surface. The breakage and the bending rigidity of composite resin coating clasps were evaluated. Results were as follows: 1) After the repeated bending test to the tips of clasp arm at 10,000 times in 0.25 mm deflection, neither crack on composite resin surface nor separation at resin/metal interface was observed in any specimen. 2) There was no significant difference in the bending rigidity of clasp arms between before and after composite resin coating. From these results, it was demonstrated that the composite resin coating cast clasp was available in clinical cases and coating with composite resin had little influence on the bending rigidity of clasp arms. Therefore, it was suggested that our clasp designing and fabricating system to control the bending rigidity of clasp arms could be applied to composite resin coating clasps.

Chromium Alloys↗
PubMedDate not supplied

An in vitro study of high-strength resin posterior denture tooth wear.

This in vitro study evaluated the wear resistance of a high-strength resin posterior denture tooth against eight opposing dental materials. The tooth specimen was cusp shaped and the opposing materials were formed as a 10 x 10 x 5 mm plate. All material combinations were tested using a machine designed to produce sliding contact 20 x 10(4) times at 60 cycles per minute and a 4-mm sliding distance per stroke in the buccolingual direction under a load of 1 kg. Wear analysis was measured as the total height loss of each material combination and the volume loss of each material. Wear against human enamel was evaluated as a control. The least loss was observed opposing a gold-silver-palladium-copper alloy, and the greatest loss was observed opposing porcelain. The volume loss of high-strength resin against gold-silver-palladium-copper alloy was as small as that against human enamel. High-strength resin wear was more significant against castable ceramics and porcelain. The volume losses of high-strength resin against high-strength resin, polycarbonate, or cobalt-chromium alloy were significantly larger than those against polyethersulfone, poly(methyl methacrylate), gold-silver-palladium-copper alloy, or human enamel. These findings suggest that the were resistance of high-strength resin is influenced considerably by opposing dental materials, and that the best combination was high-strength resin-gold-silver-palladium-copper alloy, and the poorest combination was high-strength resin-porcelain.

Analysis of Variance↗
PubMed1998

Pulpal response to a resin-modified glass-ionomer material on nonexposed and exposed monkey pulps.

OBJECTIVE: This study evaluated the biocompatibility of a resin-modified glass-ionomer material on monkey pulps. METHOD AND MATERIALS: Standardized Class V cavities were prepared in 112 teeth distributed in six healthy adult monkeys. The resin-modified glass-ionomer cement was placed in 24 nonexposed and 36 exposed pulps according to manufacturer's instructions. ZOE was used as a control in nonexposed pulps, while calcium hydroxide was used as a control for exposed pulps. Tissues were collected at 6 to 7, 21 to 27, and 90 to 97 days. After demineralization, the teeth were serially sectioned, stained, and observed by light microscopy. RESULTS: Except for one resin-modified glass-ionomer pulp at 6 days, there were no differences between the responses of nonexposed pulps to resin-modified glass-ionomer specimens and ZOE controls. In exposed pulps, eight of 36 resin-modified glass-ionomer pulps showed various grades of inflammatory response, all associated with stained bacteria. Pulpal healing was similar in both resin-modified glass-ionomer and calcium hydroxide direct-capped exposures. Twenty-two of 26 exposed pulps restored with the resin-modified glass-ionomer cement showed dentin bridge formation at 21 and 97 days. CONCLUSION: The resin-modified glass-ionomer material exhibited acceptable biologic compatibility in exposed and nonexposed cavities.

Analysis of Variance↗
PubMed1993

Localized three-body wear of six types of composite resin veneering materials.

The wear resistance of six types of composite resin veneering materials was determined in vitro by use of a three-body wear-testing device. This investigation examined the wear characteristics of the veneering composite resins in heavy occlusal contact areas. After repeated cyclic loading, wear values were measured with a profilometer, and surface textures were evaluated with a scanning electron microscope. All of the composite resin veneering materials were significantly more wear resistant than unfilled acrylic resin; but the composite resin materials demonstrated rougher surfaces than unfilled resin. Three of the composite resins exhibited fractures in the contact areas.

Acrylic Resins↗
PubMed2005

Effects of resin hydrophilicity on water sorption and changes in modulus of elasticity.

UNLABELLED: As acidic monomers of self-etching adhesives are incorporated into dental adhesives at high concentrations, the adhesive becomes more hydrophilic. Water sorption by polymers causes plasticization and lowers mechanical properties. The purpose of this study was to compare the water sorption and modulus of elasticity (E) of five experimental neat resins (EX) of increasing hydrophilicity, as ranked by their Hoy's solubility parameters and five commercial resins. METHODS: After measuring the initial modulus of all resin disks by biaxial flexure, half the specimens were stored in hexadecane and the rest were stored in water. Repeated measurements of stiffness were made for 3 days. Water sorption and solubility measurements were made in a parallel experiment. RESULTS: None of the specimens stored in oil showed any significant decrease in modulus. All resins stored in water exhibited a time-dependent decrease in modulus that was proportional to their degree of water sorption. Water sorption of EX was proportional to Hoy's solubility parameter for polar forces (delta(p)) with increasing polarity resulting in higher sorption. The least hydrophilic resin absorbed 0.55 wt% water and showed a 15% decrease in modulus after 3 days. The most hydrophilic experimental resin absorbed 12.8 wt% water and showed a 73% modulus decrease during the same period. The commercial resins absorbed between 5% and 12% water that was associated with a 19-42% reduction in modulus over 3 days.

Absorption↗
PubMed2001

Effect of three adhesive primers on the bond strengths of four light-activated opaque resins to noble alloy.

The effect of commercial adhesive primers for noble metals on the bond strength of light-activated opaque resin has not been determined. This study evaluated the effect of three adhesive primers on the shear bond strengths of each of the four light-activated opaque resins to silver--palladium--copper--gold (Ag--Pd--Cu--Au) alloy. The adhesive primers Alloy Primer (AP), Metal Primer II (MPII) and Metaltite(MT) were used. Four commercial light-activated opaque resins (Axis (AX), Cesead II (CEII), Dentacolor(DE) and Solidex (SO) were used to bond a light-activated resin-veneered composite to Ag--Pd--Cu--Au alloy. The specimens were stored in water at 37 degrees C for 24 h and then immersed alternatively in water baths at 4 and 60 degrees C for 1 min each for up to 20,000 thermal cycles before shear mode testing at a cross-head speed of 0.5 mm min(-1). All the primers examined improved the shear bond strength between opaque resin and Ag--Pd--Cu--Au alloy compared with non-primed specimens prior to thermal cycling. After 20,000 thermal cycles, the bond strengths of combined use of AP and DE and that of MT and each of AX, CE or DE were significantly greater than any other groups. Significant difference was observed between the bond strengths at thermal cycles 0 and 20,000, with the combined use of MT and DE. With the combination of appropriate adhesive metal primers and light-activated opaque resins, complicated surface preparations of metal frameworks of resin-veneered prostheses that are composed of casting Ag-Pd-Cu-Au alloy may be negligible.

Adhesives↗
PubMed2003

Effect of resin surface sealers on improvement of stain resistance for a composite provisional material.

BACKGROUND: Resistance to staining is desirable to maintain the esthetic appearance of a provisional material. A resin sealant may improve stain resistance. PURPOSE: Color changes of a resin composite provisional material were measured by reflection spectrophotometry after storage in three staining solutions and water to determine stain resistance when treated with three methacrylate or urethane dimethacrylate resin surface sealants and when left untreated. MATERIALS AND METHODS: Specimens of a resin composite provisional material received one of three resin sealants (Fortify Plus, Bisco, Inc., Schaumburg, IL; Jet Seal, Lang Dental Manfacturing, Wheeling, IL; Triad LC, Dentsply International, York, PA, USA) or no surface sealer and then were stored for 72 hours in one of four staining solutions (water [control], black coffee, cranberry juice, red wine). Color was measured by CIE L*a*b* on a reflection spectrophotometer (Color-Eye 7000, Macbeth Division, Kollmorgen Instruments, Newburgh, NY, USA) at baseline and after storage. Color change (deltaE*) was calculated and analyzed statistically by two-factor analysis of variance, with four solutions and four surface treatments as independent variables. RESULTS: deltaE* ranged from 0.7 to 1.7 in water, from 1.1 to 5.5 in cranberry juice, from 1.1 to 6.5 in black coffee, and from 1.5 to 3.9 in red wine. Statistically significant differences were observed (p < .05), with Fortify Plus showing increased staining (deltaE* > 3.3) and Jet Seal and Triad LC showing decreased staining (deltaE* < 2.0) in cranberry juice and coffee compared with staining of the unsealed specimens. Only Jet Seal provided resistance to staining in red wine. CONCLUSIONS: Specimens without a surface sealer had statistically higher (p < .05) and perceptible or nearly perceptible color changes in cranberry juice, black coffee, and red wine than in water. Specimens coated with Jet Seal had statistically lower (p < .05) color changes than uncoated specimens in cranberry juice, black coffee, and red wine. When coated, the color changes of the stained specimens were not perceptible. Specimens coated with Triad LC had statistically lower (p < .05) color changes than unsealed specimens in cranberry juice and black coffee. When sealed, the color changes of the specimens stained with cranberry juice and black coffee were not perceptible. Both unsealed and sealed specimens stained with red wine were nearly perceptible. Specimens coated with Fortify Plus had statistically higher (p < .05) color changes than uncoated specimens in cranberry juice and black coffee but statistically the same (p < .05) color change as uncoated specimens in red wine. These specimens had perceptible color changes in cranberry juice, black coffee, and red wine. CLINICAL SIGNIFICANCE: Surface of methacrylate or dimethacrylate resins can improve resistance of a resin composite provisional material to staining caused by cranberry juice, black coffee, and red wine.

Acrylic Resins↗
PubMed1998

A five-year multi-practice clinical study on posterior resin-bonded bridges.

Previous clinical observations have revealed that resin-bonded bridges for posterior tooth replacements are less retentive than anterior resin-bonded bridges. Improved bonding procedures and preparation designs, however, may have a positive effect on the functional durability of these restorations. The present study reports the final analysis of a randomized controlled clinical trial in which different designs of posterior resin-bonded bridges were evaluated for a period of at least 5 years. The operational hypothesis was that the bonding system and the preparation design used in posterior resin-bonded bridges have an influence on the survival and clinical functioning of these restorations. Survival in this study was defined at two levels: (1) 'complete' survival (survival without any debonding), and (2) 'functional' survival (survival including loss of retention on one occasion and successful rebonding of the original RBB without further debonding). With regard to 'complete' survival, no significant differences were found between the bonding systems used for adherence of the restorations to abutment teeth (etching/Clearfil F2, sandblasting/Panavia EX, and silica-coating/Microfill Pontic C). The variable 'preparation form' (conventional preparation form vs. modified preparation form) for complete survival was statistically in favor of the modified preparation form (62% vs. 46%), but did not influence the functional survival. With regard to 'functional' survival, the combination of silica coating and Microfill Pontic C was more retentive than the other bonding systems (90% survival vs. 72% and 75%, p < 0.01). Factor location was found to be highly significant for both survival levels [Cox's PH model, p = 0.0002 (Cox, 1972)]: The five-year 'complete' survival rates were 65% for maxillary restorations and 40% for mandibular restorations, while the five-year 'functional' survival rates were 89% and 68%, respectively. It is concluded that preparation of grooves in abutment teeth for posterior resin-bonded bridges is beneficial to their chance of survival. Resin-bonded bridges placed in the maxilla have a better prognosis than those made in the mandible. The bonding systems used in this study appear to have no influence on the chance of failure. In rebonded posterior resin-bonded bridges, the bonding system silica-coating/Microfill Pontic C was more retentive than the other systems tested.

Acid Etching, Dental↗
PubMedDate not supplied

In vitro studies using ion exchange resins as potential phosphate binders for renal failure patients.

The uptake of phosphate [expressed as phosphorus (P)] by the anion exchange resins, Dowex 1-X8, Dowex SBR, and Bio-Rex 5, aluminum hydroxide, and sucralfate tablets was evaluated. The maximum uptake capacities (in mg P per gram of "wet" resin or solid) were 56, 49, and 84 mg for Dowex SBR, Dowex 1-X8, and Bio-Rex 5 resins, respectively, and 164-168 mg for aluminum hydroxide and sucralfate. At a concentration of P considered to approximate that encountered in the stomach (0.3 mg/ml), Bio-Rex 5 resin, aluminum hydroxide, and sucralfate bound similar amounts of P. Physiologic concentrations of bicarbonate or chloride and simulated gastric or intestinal fluids caused small changes in P uptake by Bio-Rex 5 resin. The resins bound large quantities of taurocholic (TA) and glycocholic (GA) acids. However, when Bio-Rex 5 was converted to the taurocholate form, it bound the same amount of P as the original chloride-form resin, and the binding of TA was prevented.

Aluminum↗
PubMed2004

Bulk carbon, oxygen, and hydrogen stable isotope composition of recent resins from amber-producing Hymenaea.

Resins of Hymenaea, an angiosperm tree genus known to be a copious resin producer and a major source of amber since the Oligo-Miocene, were collected from a wide range of tropical environments from Latin America and Africa, and analyzed for their carbon, hydrogen, and oxygen stable isotope composition. The average value for delta13C in the resins was found to be -27.0+/-1.3 per thousand, which is very similar to the values reported for resins in other studies. Delta18O values for the Hymenaea resins averaged +11.2+/-1.6 per thousand, or about 20 per thousand more depleted than normal plant cellulose. DeltaD values of the resins ranged from -196 to -319 per thousand, with an average of -243+/-30 per thousand. Rough estimates suggest a fractionation of -200 to -210 per thousand between the resins and the environmental water. This value is similar to the -200 per thousand value observed for the fractionation between other plant lipids and environmental water. The present study suggests that the stable isotope composition of fossil resins (amber) has the potential to provide information on ancient environmental waters.

Amber↗
PubMed2001

Reactivity of Trametes laccases with fatty and resin acids.

Lipophilic extractives commonly referred to as wood pitch or wood resin can have a negative impact on paper machine runnability and product quality. The lipophilic extractives are composed mainly of fatty acids, resin acids, sterols, steryl esters and triglycerides. In this work, the suitability of laccases for the modification of fatty and resin acids was studied, using two model fractions. In the treatments, resin and fatty acid dispersions were treated with two different laccases, i.e. laccases from Trametes hirsuta and T. villosa. Different chromatographic methods were used to elucidate the effects of laccase treatments on the chemistry of the fatty and resin acids. Both laccases were able to modify the fatty and resin acids to some extent. In the case of fatty acids, a decrease in the amount of linoleic, oleic and pinolenic acids was observed, whereas the modification of resin acids resulted in a reduced amount of conjugated resin acids.

Abietanes↗
PubMed1994

Dimensional stability of denture bases following repair with microwave resin.

The dimensional stability of a commercially available acrylic resin, designed specifically for polymerization by microwave irradiation, was compared with that of a conventional water-bath-cured resin. Resin bases were processed on duplicate stone casts prepared from a cobalt chromium master die. Twenty bases were polymerized, using acrylic resin modified for rapid heat curing, in a water-bath at 100 degrees C for 22 min. A further 20 bases were polymerized using a microwave curing acrylic resin, in a conventional microwave oven at 500 W power output for 3 min. Ten bases from each group were sectioned in a parasagittal direction and repaired using the microwave curing resin. Following each curing cycle the fit of the posterior border of each base was evaluated via a silicone index formed between the base and the master die. The index was invested in stone and sectioned through the posterior palatal region to allow measurement of its thickness by means of an eyepiece micrometer. One-way analysis of variance and unpaired Student's t tests were employed to compare the differences in distortion at the initial cure and following repair. No significant differences were found in the distortion of the acrylic resin bases produced from the heat-cured or microwave-cured materials. All bases exhibited significant further distortion on repair with the microwave-cured acrylic resin.

Analysis of Variance↗