Effects of argon laser curing on dentin shear bond strengths

Previous studies have demonstrated the ability of the argon laser to polymerize light-activated materials and improve enamel shear bond strengths. This study was conducted to evaluate the effects of the argon laser on dentin shear bond strengths of current dentin bonding systems. Argon laser (HGM Model 8) at 231 and 280 mW, 5 sec bonding agent, 10 sec composite, and a conventional curing light (Translux EC/Kulzer) at 10 sec bonding agent, 20 sec composite were used to polymerize samples of dentin bonding systems [Scotchbond Multi-Purpose Plus (3M) and Prime Bond (Dentsply/Caulk), both with TPH (Dentsply/Caulk) composite]. A flat dentin bonding site (600 grit) was prepared on the buccal surface of extracted human teeth. Twelve samples were made for each set of parameters for both laser and conventional light totaling 48 samples. Samples were stored in distilled water in light-proof containers for 24 h at 37 degrees C. Shear bond strengths (MPa) were determined for each sample on the Instron testing machine. Mean values were calculated for each set of data and ANOVA with Fisher PLSD were used for statistical analysis. The argon laser provided bond strengths that were 21-24% greater than those of the conventional curing light system.     

Bonding of hybrid ionomers and resin cements to modified orthodontic band materials

Orthodontic bands often fail clinically at the band-cement interface. Hybrid ionomer and resin cements and a glass ionomer control were bonded to photo-etched and standard band materials, both of which were tested in as-received and air-abraded conditions. Cements were placed in a 3 mm diameter mold at the bonding interface and bonded to 6 x 6 mm stainless steel band specimens mounted to acrylic blocks. Specimens were stored in water for 24 hours at 37 degreesC and debonded in tension on a testing machine at 0.05 cm/minutes. Bond strengths (MPa) were calculated and data were analyzed by analysis of variance. Bond strengths to as-received bands were less than 3.4 MPa for cements tested, whereas bond strengths to air-abraded bands ranged from 7.1 to 17.7 MPa, except for the glass ionomer control. Air abrasion of band materials provides highly increased bond strength of hybrid ionomer and resin cements.     

The effect of air abrasion on shear bond strength to dentin with dental adhesives

This study compared the effects of different dentin surface treatments on the shear bond strengths of three adhesive systems. The adhesive systems included a resin-modified glass ionomer, Fuji II LC, and two dentin bonding systems, One Step and Scotchbond Multi-Purpose Plus. The surface treatments compared for each adhesive system were as follows: 1) the controls, which were conditioned, 2) air abrasion at 120 psi without conditioning, 3) air abrasion at 160 psi without conditioning, 4) air abrasion at 120 psi with conditioning, and 5) air abrasion at 160 psi with conditioning. The KCP 1000 Whisperjet was used for all air-abrasive specimens. Controls for each adhesive material (Fuji II LC, One Step, Scotchbond Multi-Purpose Plus) were bonded using manufacturers' recommendations. Results showed that air abrasion significantly lowered bond strength of the resin-modified glass ionomer, conditioned or nonconditioned (P < 0.01). Air abrasion alone significantly lowered bond strengths of the dentin bonding agent systems (P < 0.01). However, air abrasion plus conditioning of the dentin surface resulted in bond strengths that were similar to the conditioned-only specimens (P < 0.01).     

Bond strengths of resin-to-metal bonding systems

STATEMENT OF PROBLEM: Resinous materials for the veneers of fixed prostheses commonly require mechanical retention on metal substructures because there is no chemical adhesion. However, mechanical retention does not restrict creation of a marginal gap at the resin-metal interface, which can cause discoloration or detachment of resinous material. The development of a chemical resin-to-metal bonding could resolve this problem and also reduce the need for mechanical retention (pearls, wires) on metal frameworks. PURPOSE: This study evaluated six current methods with the use of various storage conditions to predict clinical efficacy. MATERIAL AND METHODS: Six resin-to-metal bonding systems were tested: Silicoater, Silicoater MD, Rocatec, OVS, Sebond, and Spectra-Link. All specimens were examined in bending tests after 24 hours of dry storage (category A), after 24 hours of water storage and thermocycling (category B), and after 2 months of water storage and thermocycling (category C). Tensional tests were completed for all bonding systems after dry storage, and microscopic examination (optical and SEM) was performed for all specimens. RESULTS AND CONCLUSIONS: This study indicated that certain systems can provide stable bonding of resin to metal substructures despite prolonged wet storage and intensive thermocycling. These systems can also be used clinically without retentive configurations on metal frameworks, resulting in better esthetics. Some bonding systems revealed progressive weakening of bond strengths, so research is needed to verify their clinical efficacy.     

Synergism of capillary isotachophoresis and capillary zone electrophoresis

Commercially pure titanium (CPT) substrate was subjected to porcelain firing and bond strengths under three-point bending mode (span length: 15 mm; crosshead speed: 0.5 mm/min) were evaluated. Experimental variables included surface treatments of CPT and porcelain firing schedules. Variables for the surface treatments were (1) sandblasting, (2) mono- and triple-layered nitridation, and (3) mono-layered chrome-doped nitridation. Variables for the porcelain firing schedule included (4) bonding agent application, (5) bonding agent plus gold bonding agent application, and (6) Procera porcelain application. All together eleven sample groups were prepared with different combination of aforementioned experimental variables. Statistically all of them exhibited no significant differences. Hence, we employed two further criteria; (I) the minimum bond strength should exceed the maximum porcelain strength per se, and (II) the CPT substrate should not be heated close to the beta-transus temperature. After applying these criteria, it was concluded that mono-layered nitridation and mono-layered application of chrome-doped nitridation on both (with and without) sandblasted and non-sandblasted surfaces were the most promising conditions for a successful Titanium-Porcelain System.     

Effect of aging on microleakage of restorative systems

This study evaluated the sealing properties of AP.H/Prisma Universal Bond 3, Z100/Scotchbond MultiPurpose, AP.H/Imperva Bond, Charisma/Denthesive, Bisfil M/All-Bond 2, resin composite/dentin adhesive systems and Fuji II LC light-cured glass ionomer, in Class V preparations following 6 months of storage in a 37 degrees C water bath. The Class V preparations extended just beyond the cemento-enamel junction of extracted human molars. The restored teeth were placed in 37 degrees C water for 24 hours and then thermally stressed for 100 temperature cycles. Half of the specimens were tested for microleakage at this time. The other specimens were returned to water storage and thermally stressed every 30 days during the following 6 months and then assessed for microleakage by dye penetration. AP.H/Imperva Bond, Z100/Scotchbond Multi-Purpose and Fuji II LC were not affected by the storage, while AP.H/Prisma Universal Bond 3, Charisma/Denthesive and Bisfil M/All-Bond 2 revealed some increase in microleakage at the dentin/cememtum margin.     

Determination of proton magnetization transfer rate constants in heterogeneous biological systems

Two procedures are currently in use for the determination of proton magnetization transfer rate constants between macromolecular tissue components and water. The first method assumes that there are only two spin baths (macromolecular plus solvent) and that during off-resonance irradiation complete saturation of the "immobile" proton spin bath occurs (S. H. Koenig, R. D. Brown, III, R. Ugolini, Magn. Reson. Med. 29, 311 (1993)). This approach neglects the possibility of incomplete saturation and polydispersity, and yields an apparent magnetization transfer rate constant, Kapp. The second approach utilizes a formalism which can account for polydispersity and incomplete saturation of the immobile spin bath (K. Kuwata, D. Brooks, H. Yang, T. Schleich, J. Magn. Reson., in press). In this work magnetization transfer rate constants derived by the use of both methods for two systems, ocular lens tissue and cross-linked bovine serum albumin (BSA) were compared. For both samples Kapp was dependent on B2 off-resonance irradiation frequency and power when the first method was used. The second method provided values of the magnetization transfer rate constant that were similar to the values obtained by the first method, as the limit of complete saturation was approached.     

Bond strength of six soft denture liners processed against polymerized and unpolymerized poly(methyl methacrylate)

The bond strength of six commercial soft denture liners was evaluated by a two-phase tensile test. The soft denture liners investigated were VinaSoft, Prolastic, Flexor, Molloplast-B, Novus, and SuperSoft. The samples were fabricated by processing them (1) against polymerized poly(methyl methacrylate), and (2) against unpolymerized poly(methyl methacrylate). The soft denture liners were processed according to the manufacturers recommendations. The samples were tested using an Instron Universal Testing Machine. The mode of failure, adhesive or cohesive, was also recorded. The bond strength when processed against unpolymerized poly(methyl methacrylate) ranged from 0.48 to 2.60 MPa, and when processed against polymerized poly(methyl methacrylate) the bond strength ranged from 0.94 to 2.56 MPa. A two-way analysis of variance (P = .05) revealed a significant increase in bond strength when the liners were processed against polymerized poly(methyl methacrylate), except for Novus, which had no change, and VinaSoft, which decreased. The Tukey interval between materials was .22 and between methods of polymerization was .08. Four of the six liners investigated demonstrated increased bond strength when processed against polymerized poly(methyl methacrylate). It was concluded that bonding can be influenced by the processing method.     

Dentastic bond strength to dentin

PURPOSE: To evaluate the shear bond strength to the dentin of permanent teeth and failure site of Dentastic hydrophilic dentin bonding agent. MATERIALS AND METHODS: Forty permanent noncarious molar teeth stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat with hand pressure with a series of SiC paper ending with the 600 grit to provide a uniform surface on dentin to which the resin composite could be applied. After preparing the tooth surface, the teeth were stored in distilled water for 48 hours. They were then divided at random into four groups of 10 specimens each: Group 1: Dentastic, five coats of primer; Group 2: Dentastic, three coats of primer; Group 3: Dentastic, five coats of primer, light-cured adhesive before resin bonding; Group 4: Dentastic, three coats of primer, light-cured adhesive before resin bonding. All specimens were thermocycled (500x) and sheared in a testing machine. After shear testing, the debonded sites of all samples were examined with a stereomicroscope and a scanning electron microscope. RESULTS: The results in MPa were: Group 1: 22.63 +/- 6.24; Group 2: 23.35 +/- 5.14; Group 3: 23.58 +/- 5.66; Group 4: 27.26 +/- 8.22. ANOVA and Student-Newman-Keuls showed no statistically significant difference between the groups. In all groups, all specimens failed at the dentin (dentin cohesive failure = dentin fracture) or at the resin (resin cohesive failure = resin fracture). This means that the bond strength of the product is stronger than the cohesive strengths of the dentin and the resin.     

Balneophotochemotherapy with 8-methoxypsoralen in lichen sclerosis et atrophicus

A 66-year-old woman with longstanding lichen sclerosus et atrophicus improved strikingly with PUVA bath photochemotherapy over a period of 6 weeks. The cumulative UVA dose was 31.7 J/cm2; the single UVA dose ranged from 0.3 to 2.3 J/cm2. After 16 treatment sessions, the sclerotic lesions had softened greatly, while after 24 treatments, the skin lesions were almost completely cleared and pruritus was diminished. Histopathological analysis of biopsy specimens from previously affected sites as well as 20 MHz ultrasound examinations showed almost no residual sclerosis. Although long-term results are not yet available, PUVA bath photochemotherapy seems to be a promising and effective new treatment modality without systemic side effects for patients with disseminated lichen sclerosus et atrophicus.     

Effect of etchant, etching period, and silane priming on bond strength to porcelain of composite resin

The purpose of this study was to evaluate the effect of etching and silane priming on bond strength to a feldspathic porcelain (VMK 68) of a composite resin (Clearfil APX). Two hydrofluoric acid etchants (2.5% and 5%) and seven different etching times (0, 30, 60, 90, 120, 150, and 180 seconds) were used to etch the porcelain specimens respectively. A self-curing bonding agent containing a silane coupler (Clearfil Porcelain Bond) was used on both etched and unetched porcelain surfaces. Etched relief patterns were observed by means of a scanning electron microscope, and the bond strengths between the photocured composite resin and the porcelain were determined. Scanning electron micrographs revealed complicated etching patterns with increased etching time periods. Shear testing results showed that the bond strength to the unetched porcelain of the composite resin was very low, and that etching periods for more than 30 seconds effectively enhanced the bond strength. Of the two etching agents applied to the unsilanated porcelain, the buffered 2.5% etchant produced higher bond strengths than the 5% etchant for all etching time periods except for 180 seconds. Silane priming was effective and critical for improving bond strength to the porcelain. Application of the silane bonding agent to the porcelain after hydrofluoric acid etching appeared to be suitable for achieving consistent bonding between the composite resin and the porcelain.     

Stimulation of G-CSF gene expression in the macrophage cell line by contact with extracellular matrix proteins and a pre-B leukaemia cell line

Freshly prepared dentine specimens of human teeth were perfused with either horse serum or physiologic saline. After application of AllBond2, ART Bond, Syntac or an experimental dentine bonding agent called P-Bond, a composite cylinder was added and cured at the same time. After 1500 thermal cycles with constant imitation of intrapulpal pressure, the shear bond strengths were measured. Resulting shear bond strength values were analysed with Students t-test or Mann-Whitney Test. The values for AllBond2 were not significantly different. The values for ART Bond (P < 0.05) and for Syntac (P < 0.05) were significantly higher if the dentine was perfused with horse serum. For P-Bond (P < 0.001) the values were significantly higher if the dentine was perfused with physiologic saline. According to these results it does not seem to be appropriate to take a clear decision as to which of the two perfusing media investigated might be more suitable to imitate in vivo conditions.     

Runoff Characteristics for Construction Site Erosion Control Practices

Controlling soil erosion during and after construction is a major concern due to the impacts of sediment on stream water quality, and many studies have focused on the effectiveness of erosion control best management practices (BMPs) to prevent erosion. However, their ability to reduce runoff volume and peak discharge is not commonly studied or integrated into storm water designs due to lack of data and design guidelines. This study investigated runoff characteristics (total runoff, peak flow rate, curve number, and rational method runoff coefficient) from bare compacted soil conditions with and without erosion control BMPs, with an emphasis on compost erosion control blankets (CECBs), at three different slope (2H:1V, 3H:1V, and 4H:1V). Experiments were performed in the San Diego State University, Soil Erosion Research Laboratory on a 3-m by 10-m indoor titling soil bed using simulated rainfall based on conditions specified in ASTM D-6459. Eleven erosion control BMPs were evaluated at a slope of 2H:1V, three at 3H:1V, and three at 4H:1V. The variations in slope were used to assess the effects of slope and CECB thickness on runoff. The results from this study provide new insight regarding the runoff characteristics from bare soil and erosion control BMPs that can be used to improve construction-site storm water design. The results show that 2.5- and 5.0-cm-thick CECBs on top of netting or an excelsior fiber blanket provided a significant reduction in runoff relative to the bare soil and the other BMPs (e.g., 1.3-cm CECBs, other blankets) due to water storage within the CECB, the mass of the CECB providing a strong bond between the soil surface and the bottom of the blanket reducing the potential for flowing water from coming in contact with the soil surface, and the netting/blanket under the CECB providing additional friction that helps keep the CECB from sliding down slope. The results show that slope impacts on runoff are minimal but that as CECB thickness increases runoff was reduced due to the added storage within the blanket. The results from this study can be used to aid in the selection of CECB thickness and to assess the effects of CECBs on runoff for more efficient cost effective storm water designs.     

Strength of secondary-cured resin composite inlay repairs

A study was designed to simulate the repair of an indirect resin composite restoration with conventionally cured resin composite. Two-part specimens were prepared to test the diametral tensile strength of the repair interface between the base material of an indirectly cured resin composite (Herculite XRV) and repairs carried out with three directly cured materials (Herculite XRV, TPH, and Charisma). The repairs were carried out with and without use of the bonding resin for the repair material. The diametral tensile strengths of all repaired specimens were significantly less than those of bulk unrepaired specimens. There were no significant differences between the diametral tensile strengths of repaired blocks when the repair materials were used without bonding resin. The use of an intermediate layer of bonding resin significantly increased the bond strengths obtained when Herculite XRV and TPH were used for repair. There was no significant difference between the strength values of Herculite XRV and TPH, but Charisma exhibited the lowest strengths of repaired specimens.     

Model study for subsurface trajectory of 75FeSi and SiMn ferroalloys in steel

The present study, using a low temperature model, is aimed at examining the feasibility of subsurface melting of 75FeSi and SiMn alloys added to steel baths. Wooden objects, simulating 75FeSi and SiMn of various sizes and shapes, were prepared so as to have same density ratio of 75FeSi and SiMn to steel, and their subsurface trajectories in water or zinc chloride solution following three meters of free fall through air were analyzed using video images. In general, subsurface retention times were observed to gradually increase with size of object up to a steady value. For those objects simulating 75FeSi, it was found to be dependent on shapes, spherical objects having longer retention times. The effect of shape was less pronounced for objects simulating SiMn. In a gas stirred bath, smaller cuboids for SiMn were entrained. Comparisons with estimated melting times of 75FeSi suggest that regular sized 75FeSi (ex. 20 to 50 mm) will float up and melt at the surface, when dropped to the steel bath in a ladle. A similar situation is expected with SiMn alloys. Subsurface melting may be feasible by reducing the size of 75FeSi addition from 1 to 5 mm dia. and of SiMn down to about 10 mm while simultaneously applying sufficient turbulent mixing of steel bath or providing entraining downflow velocities in the range of 10 to 30 cm/s.     

New Inorganic-organic Hybrid Tetravanadate: Preparation, Characterization and Application in Chemically Modified Electrode

A new inorganic-organic hybrid tetravanadate [Co(2,2'-bpy)3]2V4O12·11H2O(1) has been prepared and characterized. X-Ray diffraction study reveals that compound 1 contains classical cluster anions [V4O12]4-, coordi-nated cations [Co(2,2'-bpy)3]2+ and eleven water molecules, in which an interesting decamer water cluster is formed. The hybrid nanoparticles were firstly used as a bulk-modifier to fabricate a chemically modified paste electrode (1-CPE). The electrochemical behavior and electrocatalysis of 1-CPE have been studied in detail. The results indicate that 1-CPE has a good electrocatalytic activity toward the reduction of bromate in a 0.5 mol/L H2SO4 aqueous solu-tion. 1-CPE shows remarkable stability that be ascribed to the hydrogen bonding interactions between V4O12 cluster and water cluster, which are very important for practical application in electrode modification.     

Effect of application technique and dentin bonding agent interaction on shear bond strength

This study evaluated the interaction of five clinical application techniques and the shear bond strength of four DBAs (OptiBond FL, Clearfil SE Bond, PQ1 and Prime & Bond NT). A hybrid resin composite (Herculite XRV restorative resin) was attached to human dentin surfaces using five application techniques: Group A--adhesive spread with a 3M brush for 30 seconds, followed by compressed air 0.5 cm from the surface for one second to remove the excess adhesive. Group B--adhesive spread with a 3M brush for 30 seconds, followed by compressed air 0.5 cm from the surface for three seconds to remove the excess adhesive. Group C--adhesive spread with 3M brush for 30 seconds, excess adhesive removed with a clean brush, two strokes side by side, no compressed air. Group D--adhesive spread with a Micro-applicator brush for 30 seconds followed by compressed air 0.5 cm from the surface for one second to remove the excess adhesive. Group E--adhesive spread with a Micro-applicator brush for 30 seconds, the excess adhesive removed with a clean brush, two strokes side by side and no compressed air. The specimens were stored in distilled water at 37 degrees C for 24 hours, followed by thermocycling between 5 degrees C and 55 degrees C for 1,000 cycles. The shear bond strengths were determined on a universal testing machine operating with a crosshead speed of 5 mm/minute. The fracture sites were examined by 20x stereo microscope to determine the type of failure that occurred during the debonding procedure. Bond strength data were compared with analysis of variance at a significance level of p<0.05. Post hoc comparisons of means were performed with t-tests with p-values adjusted for multiple comparisons. This in vitro study concluded that there was an interaction between the application technique and bonding agent tested. All DBAs utilized the one-second compressed air technique, which yielded the highest bond strengths.     

Dyes for caries detection influence sound dentin bond strength

This study evaluated the influence of caries-detection dyes on the in vitro tensile bond strength of adhesive materials to sound dentin. Caries-free human molars were ground to expose superficial dentin. Two dyes (a commercial 0.5% basic fuchsin in propylene glycol and Cari-D-Tect) were applied to sound dentin and rinsed. Subsequently, the dentin was etched with phosphoric acid (35%) and rinsed, leaving a moist dentin surface. The adhesive (Prime & Bond 2.0) was applied in two layers and light cured. A composite (TPH Spectrum), a compomer (Dyract), and a hybrid ionomer (Advance) were used to prepare the bond-strength specimens with a 3-mm-in-diameter bonding area. Control groups were made without use of dyes. Six specimens were prepared for each group. After 24 hours in distilled water, tensile bond strength (MPa) was measured using a testing machine. Analysis of variance was used to evaluate the data. Without dyes, bond strengths of TPH Spectrum and Dyract with Prime and Bond 2.0 were similar and both values were significantly (P < 0.05) higher than that of Advance with Prime & Bond 2.0. Dyes for caries detection reduced the bond strength of TPH Spectrum and Dyract but not Advance when used with Prime and Bond 2.0.     

Bond strengths and SEM evaluation of Clearfil Liner Bond 2

PURPOSE: To evaluate a dental adhesive system that uses a single conditioning/primer agent. MATERIALS AND METHODS: Twenty-five flat enamel and dentin bonding sites were prepared to 600 grit on human molar teeth. The Clearfil Liner Bond 2 adhesive system was used to bond Clearfil AP-X composite to both enamel and dentin. After 24 hours of water storage, shear bond strengths were determined using an Instron testing machine. Fifty V-shaped cavity preparations were prepared in human molar teeth with an enamel and cementum margin. Composite restorations were placed using the new adhesive system. The teeth were stored for 24 hours, thermocycled, stained with AgNO3 , sectioned and examined for microleakage. SEM examinations were also completed to evaluate the effects of the treatment steps on enamel and dentin surfaces. RESULTS: Mean shear bond strengths for the experimental adhesive to enamel and dentin were 28.2 +/- 4.9 and 19.4 +/- 3.1 MPa. A t-test revealed that the enamel bond strength was significantly greater (P<0.05) than the dentin strength. No marginal leakage was observed from the enamel margins of the restorations. Three restorations showed minimal leakage from the cementum margins. SEM examinations showed resin penetration into both the conditioned enamel and dentin surfaces. The adhesive system produced high bond strengths to both enamel and dentin, exhibited very minimal microleakage and was easy to use.     

现役长寿的武钢5号高炉

武钢5号高炉通过采取一系列措施:优化高炉设计与炉料结构,提高入炉原燃料质量,选择合适的高炉内衬、改良炉底结构与材质,注重开炉前的基础工作与开炉初期的长寿准备,加适量的钒钛矿护炉,开发冷却壁垂直水冷管修补换新技术,维护好炉体与冷却壁,选择合理的装料制度与风口布局, 强化软水密闭循环冷却系统的日常管理等,实现了高炉强化冶炼与长寿生产,高炉利用系数达到2 229 t/(m3·d)。