Improvement In Shear Bond Strength Research Articles

Bonding properties and mechanism of the interface between precast UHPC and post-cast UHPC

In the application of UHPC joints between the precast UHPC segmental bridges, the bonding behavior of UHPC-to-UHPC interface can influence the overall integrity and the performance of the structures. The current study used the direct shear test, splitting tensile test and slant shear test to clarify the bonding properties and mechanism of the interface between precast UHPC and post-cast UHPC. The different surface preparations, including as-cast, chiseled and grooved, were considered and discussed. DIC technique was employed to observe the failure process of UHPC bond specimens. The cohesion coefficient and friction coefficient were recommended by data analysis. The results demonstrated that the UHPC bond specimens presented adhesive failure along the bonding interface without any failure was observed in the precast UHPC or post-cast UHPC. The surface preparation showed various effects on the bond strength of interface under different stress states. The bond strength of the interface is ranked from lowest to highest as follows: as-cast interface, chiseled interface and grooved interface. The interface shear bond strength increased little with chiseled preparation, but the tensile bond strength increased significantly. The interface with grooved preparation showed a greater improvement in shear bond strength than in tensile bond strength. The correlations between the interface bond strength and chemical bonding force, Van der Waals force, mechanical interlocking force and the bridge effect and dowel action of steel fibers were discussed. The values of cohesion coefficient were 0.983 MPa, 0.995 MPa and 11.818 MPa for as-cast interface, chiseled interface and grooved interface, respectively. The corresponding friction coefficient for each surface preparation was 1.065, 1.126 and 1.190, respectively.

Influence of Silver-Zinc Zeolite Incorporation on Shear Bond Strength of Silicon Cold Cure Soft Liner

Back ground: Reduction of a durable bond to acrylic denture base is the main problem associated with soft liner materials.
 Purpose: Evaluation of the influence of addition of Ag-Zn Zeolite on shear bond strength of silicon cold cure soft liner.
 Approach: thirty specimens of silicon cold cure soft liner were constructed for shear bond- strength test and divided into three groups: Control groups: 10 specimens without incorporation of Ag-Zn Zeolite, Experimental group: 10 specimens with 0.5% by weight of Ag-Zn Zeolite Experimental Group: 10 specimens with 0.75 %by weight of Ag-Zn Zeolite Plastic pattern of acrylic block with dimensions (75 mm length x 25mm width x 5mm depth )was fabricated and evaluated by Instron testing machine.
 Results: Least significant difference of (0.75%) of Ag-Zn zeolite group was significantly different compared with the experimental group of (0.5% and control group) at p<0.05.
 Conclusion: The incorporation of 0.5%, 0.75% by weight into silicon cold cure soft liner had significant effect and causes improvement in shear bond strength.

Shear bond strength of two veneering composite resins to a modified polyetheretherketone (PEEK) material: Influence of surface pretreatments and thermocycling

Objective: To research the influence of different surface pretreatment and thermocycling on shear bond strength (SBS) between veneering resins and a modified polyetheretherketone (PEEK) material.Materials and Methods: (PEEK) specimens were machined and allocated into Four pretreatment groups, Group A; no treatment, Group B; etching with 98% sulfuric acid for 1 min, Group C; air abrasion with 50 µm Al2O3, and Group D; air abrasion with 110 µmAl2O3. Surface roughness (Ra) was determined by a profilometer. Surface morphology of specimens was scanned by a Scanning Electron Microscope. Specimens were treated with Visio.link bond, divided into two subgroups; one veneered with SR Nexco and the other with Crea.lign composites. SBS was tested immediately and after thermocycling. Data were statistically analyzed using ANOVA and Tukey HSD, α = 0.05.Results: Air abrasion with 110 µm alumina significantly increased the surface roughness (P 0.05). After thermocycling, all tested groups revealed significant improvement in SBS (p<0.001). Conclusions: A modified PEEK material strengthened with 20% submicron ceramic fillers, could be treated by etching with 98% sulfuric acid for 1 min, to enhance bond strength to veneering composites and was found to have significant improvement in bond strength after thermocycling.

Shear bond strength of oil well cement in carbonic acid environment

Abstract Shear Bond Strength (SBS) is an important property of cement that determines the life of oil and gas wells. This paper presents the results of an experimental study on the effect of carbonation on the SBS of cement under high-pressure high-temperature (HPHT) condition. The study is aimed at examining the effects of CO2 concentration, temperature, and pressure on SBS of cement containing 35% of silica flour. The study was conducted by aging two types of specimens (i.e. cement cores and SBS samples made of steel pipe and cement). After curing, the specimens were aged for 14 days in an autoclave. The autoclave was 80% filled with brine saturated with mixed gas containing CO2 and CH4. Aging pressure (21–62 MPa), temperature (38–221 °C) and CO2 concentration (10–100% CO2) were varied. After aging, the specimens were recovered, and their SBS, porosity and mineralogical composition were determined to assess the level of carbonation and degradation. To identify the most dominant factor affecting the SBS of cement, measurements were analyzed applying the Analysis of Variance (ANOVA) method. The analysis showed that temperature has a more prominent effect on the carbonation process than pressure and CO2 concentration. Furthermore, results showed strong interaction effect among the main influential factors (pressure, temperature and CO2 concentration). SBS increased with the carbonation. Medium-range temperatures (107 and 177 °C) caused high levels of carbonation as manifested by huge improvement in SBS and a significant reduction in porosity after exposure to a carbonic acid environment.

Evaluation of the effect of Poly Vinyl Pyrrolidone addition on the shear bond strength of acrylic resin artificial teeth to heat cured acrylic resin denture base material

Background: The most common materials used for fabrication of denture bases are poly methyl methacrylate (PMMA). Fracture or debonding of plastic teeth from denture base are common clinical problems which are facing both the patient and the dentist. The aim of this study is to evaluate and compare the shear bond strength of acrylic resin artificial teeth treated by different chemical surface treatments (solvents like acetone & thinner) to the experimental prepared material and to the control material before and after thermocycling. Materials and methods: Preparation of modified heat cured denture base acrylic resin was carried out by preparing of (PMMA) (80%) and poly vinyl pyrrolidone (PVP) (20%) and the liquid part composed of methyl methacrylate (MMA) monomer. Control: poly methyl methacrylate (PMMA) + methyl methacrylate ( MMA ) as control group ( 2.5 : 1 ) by weight (1). Experimental: PMMA (80% ) + PVP ( 20% ) + MMA as experimental group ( 2.5 : 1 ) by weight. Sixty artificial acrylic teeth were prepared and cured by control and experimental denture base acrylic resin, then teeth were divided into three groups and treated with different surface treatment; first group received no further treatment (control), second group treated with acetone and third group treated with thinner. The denture teeth were flasked and wax was eliminated with running hot water. Denture resin was packed and cured according to manufacturer's instructions and specimens were deflasked upon the completion of resin processing. Then half of specimens from all surface treatments were tested by using Instron machine and subjected to shear force until failure. The other half of specimens which also include the surface treatments groups were thermocycled. Teeth surfaces after treatment and fracture sites were examined and photographed visually and under reflecting light microscope. Results: The results showed that all surface treatments produced significantly high improvement in shear bond strength (SBS). Control group had shown significantly lower (SBS) than experimental group bonded to artificial acrylic teeth. On the other hand, experimental denture base resin bonded to artificial acrylic teeth were affected more significantly by thermocycling than the same teeth bonded to control denture base resin. Results indicated that thinner treatment for acrylic teeth is recommended prior to denture base processing. Conclusion: higher SBS of artificial acrylic teeth bonded to experimental denture bases rather than to control denture bases.

Influence of Surface Modifications of Acrylic Resin Teeth on Shear Bond Strength with Denture Base Resin-An Invitro Study.

Debonding of artificial teeth from the denture base is an important issue for edentulous patients rehabilitated with conventional or implant supported complete dentures. The purpose of this study was to evaluate shear bond strength between denture base resin and acrylic resin denture teeth subjected to three different surface modifications on the ridge lap area as compared to unmodified denture teeth. Forty acrylic resin central incisor denture teeth were selected and randomly divided into four test groups. The teeth in each group were subjected to one of the three different surface modifications, namely, chemical treatment, sandblasting and placement of retentive grooves on the ridge lap area respectively, prior to packing of the denture base resin. The group with unmodified teeth served as control. Forty acrylic resin test blocks thus obtained were tested for shear bond strength between acrylic resin teeth and denture base resin in Universal Testing Machine. Data obtained was statistically analysed using one-way ANOVA and Student- Newman- Keul's test (p< 0.05). Analysis of shear bond strength revealed that retentive grooves on the ridge lap area showed highest bond strength values followed by sandblasting and both were statistically significant compared to the control and chemically treated groups. Unmodified surface of the resin teeth showed the least bond strength. Within the limitations of this invitro study the placement of retentive grooves or sandblasting of the ridge lap area showed highly significant improvement in shear bond strength compared to the unmodified surface. Chemical treatment did not result in any significant improvement in the shear bond strength compared to the unmodified surface.

Influence of acid-etching or double-curing time on dentin bond strength of one-step self-etch adhesive

Abstract This in vitro study was undertaken to investigate the effects of an optional etching step with 35% phosphoric acid or double curing time on the shear bond strength (SBS) of one-step self-etch adhesives to dentin. A significant improvement in shear bond strength was demonstrated when dentin was acid-etched with 35% phosphoric acid prior to the application of one-step self-etch adhesives. The use of curing time double that was recommended by the manufacturers of the respective adhesives was capable of increasing the bond strength of the Single Bond Universal Adhesive but not that of the other two adhesives (Xeno® V + and AdheSE®One F VivaPen), indicating that the bond strength is adhesive-dependent. Therefore, the use of phosphoric acid-etching on dentin is highly recommended, followed by one-step self-etch adhesives.

In vivo effects of two acidic soft drinks on shear bond strength of metal orthodontic brackets with and without resin infiltration treatment

To evaluate the in vivo effects of two acidic soft drinks (Coca-Cola and Sprite) on the shear bond strength of metal orthodontic brackets with and without resin infiltration treatment. In addition, the enamel surface was evaluated, after debonding, using a scanning electron microscope. Sixty noncarious maxillary premolars, scheduled for extraction in 30 orthodontic patients, were used. Patients were randomly divided into two groups according to the soft drink tested (Coca-Cola or Sprite). In each group, application of resin infiltration (Icon. DMG, Hamburg, Germany) was done on one side only before bonding of brackets. Patients were told to rinse their mouth with their respective soft drink at room temperature for 5 minutes, three times a day for 3 months. Shear bond strength was tested with a universal testing machine. After shearing test, a scanning electron microscope was used to evaluate enamel erosion. Statistical analysis was performed by twoway analysis of variance followed by the least significant difference test. The Coca-Cola group without resin infiltration showed the lowest resistance to shearing forces. Scanning electron micrographs of both groups after resin application showed a significant improvement compared with results without resin use, as the enamel appeared smoother and less erosive. Pretreatment with the infiltrating resin has proved to result in a significant improvement in shear bond strength, regardless of the type of soft drink consumed.

Effect of pre-etching enamel on fatigue of self-etch adhesive bonds

Objective A previous study found that the shear bond strength (SBS) to bovine enamel for the self-etching adhesive Adper Prompt-L-Pop (PLP) was 75% of that found with the etch-and-rinse material SingleBond, while the comparative value for the shear fatigue limit (SFL) was only 58% at 10 5 load cycles. Resin penetration into the enamel surface was substantially less for PLP but it was not conclusive that this was the reason for the lower results cited above. The objective of this study was to determine if pre-etching enamel would substantially improve the SBS and SFL of the PLP adhesive over those found in the previous study. Materials and methods All test methods were the same as for the previous study. SBS measurements were conducted for composite bonds to bovine enamel using a phosphoric acid pre-etch with the PLP adhesive (PLP-10) and for a conventional enamel-bonding adhesive (EB). Fatigue testing was done with the same test fixtures, load cycling at 2 Hz up to a maximum of 10 5 cycles at four selected peak load values between 35 and 60% of the respective bond strengths. Fatigue limits were determined from the data obtained. SEM analysis of resin penetration of the enamel surface was carried out for each adhesive. Results A significantly greater SBS and SFL were found for EB (SBS: 30.4 MPa; SFL: 15.6 MPa) than for PLP-10 (SBS: 20.2 MPa; SFL: 9.9 MPa). Compared with previously found results, the pre-etching of enamel had no significant improvement in SBS and only slight improvement in SFL. Resin tag penetration of the enamel surface for PLP-10 was similar to that previously found for PLP alone, suggesting that the porosity created by phosphoric acid was effectively removed by the acidic PLP adhesive. Significance Unlike some self-etching adhesives reported in the literature, pre-etching enamel did not improve the performance of the Prompt-L-Pop adhesive.

Shear bond strength of Resilon to a methacrylate‐based root canal sealer

To evaluate the adhesive strength of Resilon to Next root canal sealant (Heraeus-Kulzer), a methacrylate-based root canal sealer, using a modified microshear bond testing design. Flat Resilon surfaces of different roughnesses (smooth surface and surface roughness equivalent to 320-grit and 180-grit) were prepared by compression moulding for bonding to the sealer and compared with a composite control. The shear strength data were statistically analysed using Kruskal-Wallis one-way anova on ranks and Dunn's multiple comparison tests (alpha = 0.05). After shear testing, fractured specimens were examined using a field emission-scanning electron microscope for detailed analysis of the failure modes. The composite control exhibited significantly higher mean shear strength (7.62 MPa) that was 4.4-4.7 times those of the Resilon groups (1.64-1.74 MPa; P < 0.001). Increasing the surface roughness of the Resilon surface did not contribute to further improvement in shear bond strength for this methacrylate-based sealer (P > 0.05). Failure modes in the composite control were cohesive and mixed failures, while those in the Resilon groups were predominantly adhesive failures, with a small percentage of mixed failures. Ultrastructural evidence of phase separation of polymeric components could be identified in Resilon. Both intact, non deformed and plastically deformed Resilon surfaces could be observed in specimens that exhibited adhesive failures. The low shear strength of Resilon to a methacrylate-based sealer compared with a composite control suggests that the amount of dimethacrylate incorporated in this filled, polycaprolactone-based thermoplastic composite may not yet be optimized for effective chemical coupling to methacrylate resins.