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 523 records · Page 29Linked to original sources
PubMed1999

Laboratory evaluation of a compomer and a resin-modified glass ionomer cement for orthodontic bonding.

The mean shear debonding force of stainless steel orthodontic brackets with microetched bases bonded with either a compomer or a resin-modified glass ionomer cement was assessed. In addition, the amount of cement remaining on the enamel surface following bracket removal was evaluated. Finally, survival time of orthodontic brackets bonded with these materials was assessed following simulated mechanical stress in a ball mill. Debonding force and survival time data were compared with those obtained for brackets bonded with a chemically cured resin adhesive, a light-cured resin adhesive, and a conventional glass ionomer cement. There were no significant differences in mean shear debonding force of brackets bonded with the compomer, resin-modified glass ionomer, chemically cured resin adhesive, or the light-cured resin adhesive. Brackets bonded with a conventional glass ionomer cement had a significantly lower mean shear debonding force than that recorded for the other materials. The Adhesive Remnant Index (ARI) mode score indicated that significantly less cement remained on the enamel following debonding of brackets cemented with resin-modified or conventional glass ionomers compared with other adhesives. The median survival time for brackets cemented with the compomer, resin-modified glass ionomer, chemically cured resin, or light-cured resin were significantly longer than for brackets cemented with conventional glass ionomer. The compomer and the resin-modified glass ionomer adhesive appear to offer viable alternatives to the more commonly used resin adhesives for bracket bonding.

Acid Etching, Dental↗
PubMed2005

Detection of human neutrophil elastase with peptide-bound cross-linked ethoxylate acrylate resin analogs.

An assessment of elastase-substrate kinetics and adsorption at the solid-liquid interface of peptide-bound resin was made in an approach to the solid-phase detection of human neutrophil elastase (HNE), which is found in high concentration in chronic wound fluid. N-succinyl-alanine-alanine-proline-valine-p-nitroanilide (suc-Ala-Ala-Pro-Val-pNA), a chromogenic HNE substrate, was attached to glycine-cross-linked ethoxylate acrylate resins (Gly-CLEAR) by a carbodiimide reaction. To assess the enzyme-substrate reaction in a two-phase system, the kinetic profile of resin-bound peptide substrate hydrolysis by HNE was obtained. A glycine and di-glycine spacer was placed between the resin polymer and substrate to assess the steric and spatial requirements of resin to substrate with enzyme hydrolysis. The enzymatic activities of suc-Ala-Ala-Pro-Val-pNA and suc-Ala-Ala-Pro-Ala-pNA on the solid-phase resin were compared with similar analogs in solution. An increase in visible wavelength absorbance was observed with increasing amounts of substrate-resin and enzyme concentration. Enzyme hydrolysis of the resin-bound substrate was also demonstrated on a polypropylene surface, which was employed for visible absorbance of released chromophore. A soluble active substrate analog was released from the resin through saponification of the ethoxylate ester linkages in the resin polymer. The resin-released conjugate of the HNE substrate demonstrated an increased dose response with increasing enzyme concentration. The synthesis and assay of elastase substrates bound to CLEAR resin gives an understanding of substrate-elastase adsorption and activity at the resin's solid-liquid interface for HNE detection with a solid-phase peptide.

Acrylates↗
PubMed2006

Evaluation of the effect of water-uptake on the impedance of dental resins.

UNLABELLED: Electrical impedance spectroscopy (EIS) offers a quantitative method of measuring the stability of resin films in aqueous solution over time. PURPOSE: The purpose of this study was to measure the EIS of five experimental dental adhesive films (ca. 17 microm thick) of increasing hydrophilicity (ranked by their Hoy's solubility parameters), and how much these values change over 3 weeks in aqueous buffer. METHODS: The resin films were placed in a U-shaped chamber and a pair of Ag-AgCl electrodes was used for EIS. The EIS results were confirmed by immersing the films in 50% AgNO3 for 24 h to trace the distribution of any water absorption into the resins by TEM observations. RESULTS: The resistance (Rr) of the resins 1-4 films increased most during the first day, and varied from 1x10(11) ohm for resin 1, to 40Omega for resin 5 at day 1. The day 1 Rr values of resins 1-4 were inversely proportional to their Hoy's solubility parameter for hydrogen bonding forces. Electrical impedance values of resins 1-3 and 5 varied widely but were relatively constant over time, while those of resin 4 decreased more than 99% from day 1 to 21 (p<0.05). Capacitance (Cr) of films of resins 1-4 all increased over the first day and then were relatively unchanged over the 20 days (except for resin 4 that continued to increase) and were between 0.01 and 1 nF. Silver uptake by TEM revealed the development of water-filled branching structures that formed in resins 4 and 5 over time.

Adhesives↗
PubMed2003

The effect of fiber reinforcement type and water storage on strength properties of a provisional fixed partial denture resin.

Fracture resistance of provisional restorations is an important clinical concern. This property is directly related to transverse strength. Strengthening of provisional fixed partial dentures may result from reinforcement with various fiber types. This study evaluated the effect of fiber type and water storage on the transverse strength of a commercially available provisional resin under two different conditions. The denture resin was reinforced with either glass or aramid fiber or no reinforcement was used. Uniform samples were made from a commercially available autopolymerizing provisional fixed partial denture resin. Sixteen bar-shaped specimens (60 x 10 x 4 mm) were reinforced with pre-treated epoxy resin-coated glass fibers, with aramid fibers, or with no fibers. Eight specimens of each group, with and without fibers, were tested after 24 h of fabrication (immediate group), and after 30-day water storage. A three-point loading test was used to measure the transverse strength, the maximal deflection, and the modulus of elasticity. The Kruskal-Wallis Analysis of Variance was used to examine differences among the three groups, and then the Mann-Whitney U Test and Wilcoxon Signed Ranks Test were applied to determine pair-wise differences. The transverse strength and the maximal deflection values in the immediate group and in the 30-day water storage group were not statistically significant. In the group tested immediately, the elasticity modulus was found to be significant (P = 0.042). In the 30-day water storage group, all the values were statistically insignificant. The highest transverse strength was displayed by the glass-reinforced resin (66.25MPa) in the immediate group. The transverse strength value was 62.04MPa for the unreinforced samples in the immediate group. All the specimens exhibited lower transverse strength with an increase in water immersion time. The transverse strength value was 61.13 MPa for the glass-reinforced resin and was 61.24 MPa for the unreinforced resin. The aramid-reinforced resin decreased from 62.29 to 58.77 MPa. The addition of fiber reinforcement enhanced the physical properties (the transverse strength, the maximal deflection, the modulus of elasticity) of the processed material over that seen with no addition of fiber. Water storage did not statistically affect the transverse strength of the provisional denture resin compared to that of the unreinforced resin. The transverse strength was lowered at water storage but it was not statistically significant. The transverse strength was enhanced by fiber addition compared to the unreinforced resin. The glass fiber was superior to the other fiber. Also the modulus of elasticity was enhanced by fiber addition compared to the unreinforced resin.

Acrylic Resins↗
PubMed1990

New type metal bracket for suppression of resin remaining in debonding.

A new type of metal bracket was prepared to minimize the destruction at the bracket-resin interface and to suppress resin from remaining on the tooth surface in debonding. The brackets were made of stainless steel and had a modified cylindrical outward shape (phi 3.8 mm x 1.8 mm), twin-type wings, and a 0.018 inch (0.457 mm) slot. Retentive forces and debonding aspects of residual resin for the brackets were studied using three representative adhesives. The mean tensile strengths at the bracket-resin interface were over 80 kgf/cm2 for all three resins. As the quantitative evaluation for the residual resin condition, a resin remaining ratio (RRR) was adopted. The aspects of the residual resin differed according to the type of adhesive resin used. Almost no resin was detected on the tooth surface just below the central part of the bracket, and even for the peripheral part which did not have an effective resin retention form, the RRR was under 30% for the heavily filled resin.

Acrylic Resins↗
PubMed1989

[Fundamental study on photocured resin for crown and bridge].

The purpose of this study is to clarify the superiority of five polyfunctional acrylates to composite filler and comonomer system, and the reasonable concentration of catalyst, Camphor quinone/Dimethylamino-ethylmethacrylate (CQ/DMAEMA), in the photocured resin for crown and bridge. The results are summarized as follows: 1. The influence of acrylate resin matrix of composite fillers was found in the elastic modulus (Em), Knoop hardness (Hk) and the wear resistance (Rw) of the photocured resin. Two photocured resins including Dipentaerythrytol hexaacrylate (DPHA) or DPHA-4(3-acryloxy propyl) tetramethylol methane (DPHA-APTM) composite fillers showed a higher Em, Hk and Rw but slightly lower tensile strength (Ts) and bending strength (Bs) than the one which included Bis-2-methacryloxyethyl 2, 2, 4-trymethyl hexamethylene diurethane (UDMA) or Trimethylolpropane trimethacrylate (TMPTMA) under a wet condition. And these two resins showed as a high water sorption value (Ws) as that of the photocured resin of UDMA. 2. The conversion of polymerization, cured depth and physical properties (Em, Hk and Rw) of the photocured resins were examined. They increased up to 0.5/1.0 or 1.0/1.0 in proportion to the increase of the concentration of the catalysts (CQ/DMAEMA). 3. When DPHA was added into the photocured resins consisted with UDMA monomer and DPHA or DPHA-APTM composite fillers, these resins showed a higher Em, Hk and Rw than the photocured resin with only UDMA as monomer. No significant difference of Ts and Bs between the photocured resins with and without DPHA was observed under a dry condition, but the values of Ts and Bs decreased in proportion to the increase of DPHA monomer under the wet condition. The residual monomer of the photocured resins was less than 1.2 per cent.

Acrylic Resins↗
PubMed2001

Effects of filler composition and surface treatment on the characteristics of opaque resin composites.

The effects of filler composition and surface treatment of titanium dioxide (TiO2) on the shear bond strength to noble metal and mechanical properties of opaque dental resin composites were assessed. A series of fillers for resin composites were prepared with untreated TiO2 or treated silica/alumina-coated TiO2 with silane coupling agent; these fillers were replaced with silanized SiO2 in increasing amounts. Each of various powder compositions were mixed with the liquid and applied to the surface of a silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy and light cured. A light-activated resin-veneering composite material was placed on top with the use of a brass ring mold and light cured. Specimens were stored at 37 degrees C in water for a period of 24 h. Additionally some specimens were thermocycled at 4 degrees C and 60 degrees C in water baths for 1 min each for 5000 cycles before shear mode testing was performed. Light-activated opaque resin composites containing filler with specific filler compositions of 50 wt% of untreated TiO2-50 wt% of silanized SiO2 (untreated TiO2(50)) and 40 wt% of untreated TiO2-60 wt% of silanized SiO2 (untreated TiO2(40)) showed higher shear bond strengths to the Ag-Pd-Cu-Au alloy than any other specific compositions when no thermocycling was involved. Surface treatment of TiO2 filler and TiO2(50)- and TiO2(40)-opaque resin composites prepared thereof showed significantly higher shear bond strengths than untreated TiO2(50)- and TiO2(40)-opaque resin composites when subjected to thermocycling. Surface-treated opaque resin composite had significantly higher compressive and flexural strength than untreated opaque resin composite after immersion in water for 1 month. Scanning electron microscopy of the fractured opaque resin composite surface showed an interface failure between TiO2 and the matrix resin for untreated composite, and cohesive failure within the resin for surface-treated composite. Surface-treated TiO2(50) and TiO2(40) may be clinically useful as the filler for light-activated opaque dental resin composites.

Adhesiveness↗
PubMed2004

Influence of the microporosity and surface chemistry of polymeric resins on adsorptive properties toward phenol.

In this work, the effects of the microporosity and chemical surface of polymeric adsorbents on adsorptive properties of phenol were investigated. Textural parameters of four kinds of polymeric resins, namely AB-8, D4006, NKA-II and D16 resin, were separately measured by ASAP 2010. The surface chemistry of these polymeric resins was determined by means of inverse gas chromatography (IGC) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Static equilibrium adsorption experiments were carried out to obtain the isotherms of phenol on the polymeric resins. It was shown that NKA-II and AB-8 resin possessed relatively high BET surface areas and micropore volumes, while D4006 and D16 resin possessed comparatively low BET surface areas and micropore volumes. The results of IGC experiments revealed that NKA-II resin had extraordinary high specific component of the free energy of adsorption both for polar acetone and benzene probe, and thus extraordinary strong surface polarity compared to the other polymeric resins. It was also found that the isotherm of phenol on NKA-II was much higher than that on the other polymeric resins due to its strongest surface polarity and largest micropore volume among four kinds of resins. These experimental observations indicated that adsorption of phenol on the polymeric resins depended greatly on their microporosity and surface chemistry. The well-developed microporosity and the strong surface polarity would improve the adsorption of phenol on the polymeric resins.

Adsorption↗
PubMed2000

Dimensional accuracy of an epoxy resin die material using two setting methods.

STATEMENT OF PROBLEM: Resinous die materials have several important advantages including strength, abrasion resistance, and detail reproduction. Despite these advantages, the shrinkage of resinous die materials during polymerization has limited their widespread acceptance. PURPOSE: This study determined whether a retarded setting reaction could improve the accuracy of an epoxy resin die system, and compared the accuracy of this epoxy resin system with gypsum-based die materials. MATERIAL AND METHODS: Four groups were compared: an epoxy resin manipulated according to manufacturer's instructions (Ivoclar, Schaan, Liechtenstein); the same epoxy resin manipulated to undergo a retarded set; a high-strength high-expansion gypsum (Die Keen); and a resin-filled gypsum (Resin Rock). Ten dies were fabricated for each material from a master metal model using conventional prosthodontic laboratory techniques. The mean of 3 independent measurements recorded using a toolmaker's microscope and digital positioners was used to describe each die. RESULTS: One-way ANOVA revealed that significant differences existed among the materials (P <.0001). Tukey's multiple comparisons testing ranked the dies as follows, from largest to smallest: high-strength high-expansion gypsum, resin-filled gypsum, master metal model, retarded epoxy, and manufacturers epoxy (P <.05). CONCLUSION: Retarding the setting reaction of an epoxy resin die material improved its accuracy. Of the materials tested, retarded set epoxy dies had the least mean dimensional change from the metal master. Epoxy resin die materials had a net shrinkage, but the gypsum-based materials had a net expansion. The epoxy resin materials exhibited more variability than the gypsum-based materials.

Analysis of Variance↗
PubMed1998

Comparison of bond strengths of three denture base resins to treated nickel-chromium-beryllium alloy.

PURPOSE: In-vitro bond strengths of 3 denture base resins (Trutone, Lucitone 199, and Triad) to a nickel-chromium-beryllium removable partial denture alloy (Ticonium) were tested with 3 surface pretreatments: sandblast, acid etch, and Rocatec (silica blasting), with or without primers (Dentsply, CR inlay cement, and Super Bond). MATERIAL AND METHODS: Lucitone 199 denture base resin bonded to the nonprimed sandblasted alloy specimen served as the control group. Alloy specimens were prepared, surface treated, and primed or not primed with primer. The treated specimens were then packed and processed with the denture base resin. Bonded specimens were stored in the distilled water at 37 degrees C for 24 hours, and then debonded in tension. The force at which the bond failed was noted, and bond strength was calculated in megapascals (MPa). Five replications for each condition (180 specimens total) were tested. RESULTS: Significant differences in bond strength were observed with primer, the most important factor, followed by pretreatment and denture base resin. Without primer for all 3 denture base resins, the Met-Etch and Rocatec treated group showed significantly higher bond strengths than the sandblasted groups. For Trutone denture base resin, nonprimed treated groups produced significantly higher bond strength than those for the other 2 denture base resin, nonprimed treated groups produced significantly higher bond strength than those for the other 2 denture base resins. The control group had zero bond strength. For Dentsply primer, the Rocatec treated group bonded to Lucitone 199 resin produced the highest bond strength value (14.8 +/- 1.8 MPa). For CR inlay cement, the Met-Etch and Rocatec treated groups for Lucitone denture base resin demonstrated the highest bond strength (19.3 +/- 4.8 MPa, and 19.3 +/- 1.8 MPa, respectively). For super Bond primer, the Met-Etch treated group for Trutone resin demonstrated the highest bond strength (19.8 +/- 6.2 MPa). CONCLUSIONS: Without primer, the control had the lowest bond strength (0 MPa), and the Trutone groups showed the highest bond strength (11.7 +/- 4.1 MPa). Met-Etch and Rocatec treated groups produced higher bond strengths than the sandblasted groups. The primed specimens demonstrated significantly higher bond strengths than nonprimed specimens, except for Trutone resin, for which primed specimens produced lower bond strengths than the nonprimed specimens.

Acid Etching, Dental↗
PubMed2001

Fracture resistance of dentin-composite interfaces using different adhesive resin layers.

OBJECTIVES: The objective of this study was to study the effect of different adhesive layers on the interfacial fracture toughness (K(ICi)) of dentin-resin composite interfaces. METHODS: Miniature short-rod fracture toughness specimens containing a chevron-shaped dentin-bonded interface along their midplane were used for testing. Each interface zone contained a thinned (one coat of unfilled adhesive resin, air-thinned), one-layer (one coat of unfilled adhesive resin, brush-thinned), two-layer (two coats of unfilled adhesive resin, brush-thinned), 10% filled or 45% filled adhesive resin layer. After storage in distilled water at 37 degrees C for 24h, the fracture toughness test specimens were loaded in tension at an extension rate of 0.5mm/min until fracture and the K(ICi) were determined. The results were analysed by ANOVA and Fisher's LSD test (p<0.05). Scanning electron microscopy was used to examine representative fracture surfaces. RESULTS: There were no significant differences in mean K(ICi) among the different unfilled adhesive resin layer groups. SEM examination of these specimens showed that fracture generally occurred between the resin-infiltrated layer and adhesive resin layer during interfacial fracture toughness testing. The mean K(ICi) for the 10% filled groups was not significantly different from the unfilled groups. The 45% filled group, however, demonstrated the highest K(ICi) values, the thickest adhesive resin layer under SEM examination, and a fracture path through the adhesive resin layer. CONCLUSIONS: There were no significant differences in K(ICi) when the unfilled adhesive resin was used despite different application methods. The 45% filled adhesive resin improved the properties of the dentin-composite interface with respect to both interfacial fracture resistance and dentinal seal after fracture.

Acid Etching, Dental↗
PubMed1996

Laser-aided degradation of composite resin.

The removal of residual composite resin after debonding orthodontic brackets often creates surface scratches, enamel loss, and enamel tearouts. If the Nd:YAG laser could selectively degrade the resin without damaging the underlying tooth structure, these problems might be eliminated. The purpose of this study was to determine the effectiveness of the Nd:YAG laser in degrading composite resin within a time frame that will not cause pulpal damage. Minimal lasing times and optimum frequencies were determined by testing the compressive strengths of resin cylinders exposed to laser radiation for 2, 3, 5, 10, or 15 seconds at frequencies of 60, 80, or 100 Hz. The optimum condition was determined to be a 3 second lasing time at a frequency of 100 Hz. Cylinders of composite resin were divided into four groups consisting of: (1) resin, (2) resin with a laser enhancing dye, (3) resin lased for 3 seconds at 100 Hz, and (4) resin with the dye which was lased for 3 seconds at 100 Hz. The compressive strengths of the four groups were statistically compared. The resin groups that were lased for 3 seconds at 100 Hz showed a 75% reduction in compressive strength. The results of this study demonstrate that dual wavelength pulsed Nd:YAG laser energy, when used within the parameters described here, will degrade the mechanical properties of composite resin, thereby offering the potential for a quick and efficient method of removing residual composite resin.

Aluminum Silicates↗
PubMed1998

Distribution of calcium ions at the interface between resin bonding materials and tooth dentin. Use of commercially available adhesive systems.

It has been proposed that calcium ions play a key role in chemical (chelate) binding between the adhesive resin and dentin surface. However, no data is available concerning how calcium ions are distributed at the binding sites. The aim of this study is to demonstrate calcium ions at the resin-dentin interface by means of X-ray microanalysis and calcium ion-sensitive histochemical staining. The dentin surface in human teeth was ground by use of 240 grit silicon carbide abrasive paper under running water and treated with the dentin-primer and adhesive resin in Clearfil Liner Bond System or IMPERVA Bond System according to the manufacturer's instructions. After removing dentin matrix and isolating adhesive resin by the KOH-digestion method, one half of the samples were processed for scanning electron microscopy. The rest were embedded in Epon 812 and processed either for glyoxal bis (2-hydroxyanil) (GBHA) staining or transmission electron microscopy combined with X-ray microanalysis. Transmission electron microscopy revealed Ca-phosphate deposits at the bottom of the resin-impregnated layer. The adhesive resin above the resin-impregnated layer was amorphous and showed no precipitates of Ca-phosphate. GBHA displayed intense calcium reactions throughout the resin-impregnated layer and also moderate ones in the 10 microns (Clearfil Liner Bond System) or 30 microns (IMPERVA Bonding System) thick boundary zone of the adhesive resin as well as in the resin tags. These data are the first to offer a distinct localization of calcium ions within the adhesive resin at the dentin-resin interface.

Calcium↗
PubMed1995

Resin bonding efficacy of Gluma 2000 to dentine of primary teeth: an in vitro study.

The aim of this study was to investigate (i) the effect of Gluma 2000 conditioning solution on the dentine of primary teeth, (ii) the penetration of Gluma 2000 adhesive resin into the etched dentine, (iii) the shear bond strength of a composite resin restorative material (Pekafill) bonded with Gluma 2000 to dentine, and (iv) the depth of penetration of adhesive resin into the etched dentine as a function of the conditioning time. Dentine surfaces conditioned for 15, 30, 60 and 120 seconds were examined by scanning electron microscopy. The smear layer was totally removed and, with the longer conditioning times, a fine crystalline precipitation, presumably calcium oxalate, was formed. After Gluma 2000 bonding of composite resin and dissolution of the teeth the resin interface showed excellent penetration into the etched dentine. Shear bond strengths of composite resin bonded with the adhesive resin were similar following conditioning for 15, 30, 60 and 120 seconds. Microphotographs of debonded specimens indicated that the mode of failure was cohesive within the resin. The depth of penetration of resin into etched dentine was determined by scanning electron microscopy, and a linear relationship was found between the thickness of the resin-impregnated layer and conditioning time. It was therefore concluded that depth of resin penetration and shear bond strength are not correlated. The study shows that the Gluma 2000 bonding system produces reliable adhesion of composite resin to dentine of primary teeth.

Acid Etching, Dental↗
PubMed1984

The transverse strength of acrylic resin strips and of repaired acrylic samples.

A method was developed for measuring the transverse strength of repaired acrylic samples at a single butt joint. The strength was determined for samples prepared from two types of heat polymerizing resins and two types of repair resins. The temperature elevation during curing of the repair resins was determined. Cross-linking of the resins was evaluated by immersion of samples in solvents. The appearance of the bead microstructure after various treatments was considered to indicate relaxation at the sample surface. Repaired samples of the heat polymerizing resin which exhibited relaxation after immersion in monomer, had a lower strength than samples prepared from the resin for which relaxation was not observed, although both resins were cross-linked to a similar extent. The application of pressure during curing increased the strength of the samples repaired with the rapid curing, cross-linked, repair resin. The strength of the samples repaired with the uncross-linked, slow curing, repair resin was affected by pressure only if the insertion of the repair resin between the sample parts was delayed after mixing. Variations in the powder to liquid ratio of the uncross-linked repair resin did not affect the sample strength. Wetting of the sample parts with monomer before repair, and variations in the curing temperature did not affect the sample strength for the investigated resin combinations.

Acrylic Resins↗
PubMed2000

Tensile bond strength of resin-modified glass-ionomer cement to microabraded and silica-coated or tin-plated high noble ceramic alloy.

PURPOSE: The purpose of this study was to evaluate the influence of alloy surface microabrasion, silica coating, or microabrasion plus tin plating on the tensile bond strengths between a resin-modified glass-ionomer luting cement and a high-noble alloy. Bond strength between the microabraded alloy specimens and conventional glass-ionomer cement or resin cement were included for comparison. MATERIALS AND METHODS: One hundred twenty uniform size, disk-shaped specimens were cast in a noble metal alloy and divided into 6 groups (n = 10 pairs/group). The metal surfaces of the specimens in each group were treated and cemented as follows. Group 1: No surface treatment (as cast, control), cemented with a resin-modified glass-ionomer cement. Group 2: Microabrasion with 50-microm aluminum oxide particles, resin-modified glass-ionomer cement. Group 3: A laboratory microabrasion and silica coating system, resin-modified glass-ionomer cement. Group 4: Microabrasion and tin-plating, resin-modified glass-ionomer cement. Group 5: Microabrasion only, conventional glass-ionomer cement. Group 6: Microabrasion and tin-plating, conventional resin cement. The uniaxial tensile bond strength for each specimen pair was determined using an Instron Universal Testing Machine (Instron Corp, Canton, MA). Results were analyzed using a one-way analysis of variance (alpha = 0.05) and a Tukey post-hoc analysis. RESULTS: Mean bond strength: Group 1: 3.6 (+/- 1.5) MPa. Group 2: 4.2 (+/-0.5) MPa. Group 3: 6.7 (+/- 0.9) MPa. Group 4: 10.6 (+/- 1.8) MPa. Group 5: 1.1 (+/- 0.4) MPa. Group 6: 14.6 (+/- 2.3) MPa. Group 6 was significantly stronger than Group 4. The bond strength of specimens cemented with the resin-modified glass-ionomer cement using microabrasion and tin-plating (Group 4) was significantly stronger than all other groups except the resin cement with microabrasion and tin-plating (Group 6). CONCLUSION: Microabraded and tin-plated alloy specimens luted with the resin-modified glass-ionomer cement resulted in the greatest mean tensile strengths for the resin-modified glass-ionomer cement groups. This strength was 73% of the mean tensile strength of microabraded specimens luted with resin cement.

Aluminum Oxide↗
PubMed1991

Occupational skin diseases from epoxy compounds. Epoxy resin compounds, epoxy acrylates and 2,3-epoxypropyl trimethyl ammonium chloride.

Of a total of 3731 patients investigated between 1974 and 1990, 1844 (49.4%) had an occupational skin disease. Of them 142 (7.7%) had an occupational skin disease caused by epoxy compounds--135 patients (95%) had allergic contact dermatitis, five had irritant contact dermatitis, and two had contact urticaria. Apart from dermatoses, two patients had IgE-mediated asthma from exposure to DGEBA epoxy resins. Thus epoxy compounds are one of the main causes of occupational allergic contact dermatoses and can be considered potential causes of occupational asthma. The most frequent causes were epoxy resin compounds, which together induced 93% (132 cases) of all epoxy compound dermatoses. The three most common causative products were epoxy paints and their raw materials (31%, 41 cases), epoxy resin compounds used in electrical insulation (29%, 38 cases) and epoxy glues (18%, 24 cases). Fewer cases were caused by products containing epoxy acrylate and EPTMAC. The present study found that, in addition to contact allergy to DGEBA epoxy resins, contact allergy to epoxy hardeners, non-DGEBA resins and reactive diluents is common. Polyamine hardeners, most frequently MDA, DETA and TETA, rarely IPDA, tris-DMP, EDA, TMD and XDA, were the second commonest causes of contact allergy induced by epoxy resin compounds, after DGEBA epoxy resins. Cycloaliphatic epoxy resins and other non-DGEBA epoxy resins, including heterocyclic dimethyl hydantoin, phenol novolak and brominated epoxy resins, were the third commonest causes, and reactive diluents the fourth commonest cause of allergic dermatitis due to epoxy resin compounds. Most patients sensitized to reactive diluents were allergic to PGE, ortho-CGE, HDDGE and BDDGE, whereas fewer patients were sensitized to AGE, NPGDGE and BGE. Cross-sensitization between reactive diluents was common. Cardura E 10 and Epoxide 8 provoked no reactions. The present study also indicated that DGEBA epoxy resins with a high average MW ought to be regarded as potential sensitizers, and organic solvents probably promote sensitization to DGEBA, even if the amount of DGEBA is low in the causative products. When contact dermatitis induced by epoxy compounds is suspected, an accurate diagnosis is made with the use of detailed data on the patient's exposure and extensive patch testing, including tests with the patient's own products. No chemical can be used alone to screen for sensitization to all different contact allergens of epoxy compounds.(ABSTRACT TRUNCATED AT 400 WORDS)

Benzhydryl Compounds↗
PubMed2000

Effect of stepped light exposure on the volumetric polymerization shrinkage and bulk modulus of dental composites and an unfilled resin.

PURPOSE: To compare the volumetric polymerization shrinkage and dynamic bulk modulus of five resins and an experimental unfilled resin polymerized with a stepped power light and with a conventional one step curing light. MATERIALS AND METHODS: Parallel sided glass rings 5 mm in diameter and 2 mm high were etched for 5 min with hydrofluoric acid and silanated. The density and volume of the rings were calculated before they were filled with either SureFil, AEliteflo, Pertac II, Z100, or an experimental unfilled resin. When cured, the resin was bonded to the glass ring which produced a mold with a configuration C-factor of approximately 0.8. The resin was cured for 40 s on each side using either a one step curing light or a stepped power curing light. After curing, the specimens were weighed in air and in water to calculate their final density and volumetric shrinkage. Ten samples were made using each light system and for each resin (total of 100 samples). The bulk modulus was determined for each resin using an ultrasonic method, and the percentage filler contents were determined by thermogravimetric analysis. RESULTS: The mean +/- SD volumetric polymerization shrinkage values ranged from 3.10 +/- 1.19% for SureFil using the one step light to 12.35 +/- 1.38% for the unfilled resin using the stepped power curing light. Student-Newman-Keuls post hoc test separated the 10 different materials into three significant groups at P= 0.05. The unfilled resin exhibited the highest volumetric shrinkage followed by the flowable composite (AEliteflo). For all materials tested, there was no significant difference in the volumetric shrinkage values when the resin was cured with the one step or the stepped power curing light. There was no significant difference in the volumetric shrinkage values for the hybrid composites (Pertac II, Z100, and SureFil). The volumetric shrinkage values were highly sensitive to filler weight (P < 0.001). Except for Z100, there was no difference in the specific gravity values and velocities of the longitudinal and shear waves and bulk modulus when the one step and stepped power curing lights were used. The bulk modulus values ranged from 6.30 +/- 0.19 GPa for unfilled resin, to 17.10 +/- 1.09 GPa for Z100. Curing with the one step or the stepped curing light had no significant effect on the modulus values for any resin with the exception of Z100, P = 0.05. The bulk modulus values were highly sensitive to filler weight, and higher modulus values were associated with increased filler weight (P < 0.001). There was no significant difference between the bulk modulus of Pertac II and SureFil (P = 0.05).

Acid Etching, Dental↗