Effect of different application techniques on microshear bond strength of self-etch adhesives to dentin

Objectives: To investigate the effect of different self-etch adhesive systems application techniques: active or passive in a single or double layer on adhesive–dentin microshear bond strength.

Methods: Occlusal surfaces of 48 extracted human molars were ground to expose flat superficial dentin surfaces. Specimens were randomly divided into two main groups according to the tested self-etch adhesive system either: One-step self-etch (Adper^TM easy-one) or two-step self-etch (Adper^TM SE Plus). Each adhesive system was applied on the prepared dentin surfaces followed one of these techniques: (1) Passive application of a single layer, (2) Active application of single layer, (3) Passive application of double adhesive layer (with light curing in between), and (4) Active application of double adhesive layers. Resin composite was packed inside micro-tubes fixed on the bonded dentin surfaces and light cured for 40 s. All specimens were stored in artificial saliva either for 24 h or 3 months before testing. Microshear bond strength test was employed using a universal testing machine at a crosshead speed of 0.5 mm/min.

Results: Adper^TM SE Plus showed higher significant microshear bond strength in compared with Adper^TM easy-one. For both adhesive systems active application showed higher significant microshear bond strength to dentin than passive application. Double application of adhesive systems showed lower microshear bond strength than single application.

Conclusion: Active application of self-etch adhesives could improve the dentin microshear bond strength. Double application with curing in between the layers did not improve the bond strength to the tested adhesive.     

样品制备工艺对石材干挂胶性能测试结果的影响

探讨了石材干挂胶性能测试中样品制备工艺对钢/钢拉剪强度和冲击强度测试结果的影响。结果表明,制备钢/钢拉剪样品时用垫丝控制胶层厚度的方法,控厚更精确,测试结果重复性好;相比于硅胶模具,钢模具制2备的试样冲击强度要高出0.5~0.8 k J/m,样品制备中不同的表面找平方法对冲击强度的影响相对较小。     

One-year bonding performance of one-bottle etch-and-rinse adhesives to dentin at different moisture conditions

Abstract

This study aimed to investigate the one-year bond strengths to dentin of one-bottle etch-and-rinse adhesive systems applied under different moisture conditions. Class V cavities were prepared in bovine incisors and randomly allocated (n?=?8) according to the type of adhesive system used – SB (Adper? Single Bond 2); PB (Prime & Bond 2.1); and XPB (XP Bond) – and the moisture condition kept in the cavity – moist, over-wet, and over-dry. Filtek? Z250 was used for teeth restoration. Specimens for microtensile bond strength (µTBS) test were obtained and stored in water for 24?h or 1?year, and submitted to mechanical testing. Data were analyzed using t-tests, ANOVA and the Holm–Sidak post hoc test (α?=?0.05). Weibull analysis was used to verify the reliability of specimens. The type of adhesive and the moisture condition of the substrate affected the µTBS. At 24?h, SB performed better under the moist and over-wet conditions. At 1?year, SB, PB, and XPB showed the greatest percentage reduction at the moist (～38%), over-wet (100%), and over-dry (100%) conditions, respectively. The reliability of adhesives was affected by the variable factors tested. In conclusion, the solvent composition of adhesives and the moisture condition of the substrate play an important role in the bond strength and bonding stability of resin-based restorations, as well as on the reliability of the adhesive interfaces over time.     

Influence of the mechanical behaviour of different adhesives on an interference-fit cylindrical joint

Hybrid adhesive joining techniques are often used in many industrial sectors to design lightweight structures. A hybrid adhesive joint results from the combination of adhesive bonding with other traditional joining methods such as welding and mechanical fastening, with the aim of combining the advantages of the different techniques and overcoming their drawbacks.This study focuses on the interference fitted/adhesive bonded joining technique. In this application, two cylindrical components are coupled together by inserting one into the other, after having placed an adhesive between them. Generally anaerobic acrylic adhesives, also known as “retaining compound” are used for this application. However the effect of the adhesive nature and of its mechanical and adhesive responses on the performance of the hybrid joint is still unclear. The aim of the present research is to improve the understanding of the behaviour of different adhesives, including rigid epoxies and flexible polyurethanes, in the presence of an interference-fit. Static strength of bonded and unbonded interference fit joints have been compared in order to investigate the role of the different adhesives.     

The chemical,kinetic and mechanical characterization of tannin-based adhesives with different crosslinking systems

Network formation, cure characteristics and bonding performance of tannin-based resins were investigated in order to establish structure–property relationships between the stage B and stage C. Tannin–aldehyde and base-catalyzed autocondensed tannin resins were synthesized and characterized for molecular weight distribution, cure kinetics and cure chemistry by means of GPC, DMA and ¹³C CP/MAS NMR spectroscopy and solvent stability tests. The resins performance as wood adhesives was further established from lap-shear tests and microscopic observation of the bondline. Resins prepared with highly reactive aldehydes, such as formaldehyde or glyoxal, exhibited a significant extent of hetero-condensation reactions, fast cure kinetics, a high storage modulus and good solvent stability of the stage C-resin. In contrast, resins prepared with bulky aldehydes of low reactivity, such as citral, were dominated by autocondensation reactions, and exhibited slower cure kinetics, a lower storage modulus and solvent-stability of the stage C-resin, alike those neat autocondensed tannin resins. However, all resin systems fulfilled the standard requirements for wood adhesive bonding for interior applications. Additionally, storage modulus increase during cure was found to be a good predictor of the stiffness of the wood-bonded assembly, useful to discriminate between the autocondensation and heterocondensation cure chemistries.     

Efficacy of different surface treatments and universal adhesives on the microtensile bond strength of bulk-fill composite repair

Abstract

The purpose of this in vitro study was to evaluate the influence of different surface treatments and aging on the microtensile bond strength (μTBS) of bulk-fill composite resins. Bulk-fill composites (Filtek One; 3M ESPE) randomly received five different surface treatments: (1) no treatment, control, (2) 37% phosphoric acid etching (PA), (3) 9% hydrofluoric acid etching (HF), (4) air-borne particle abrasion with 50-μm alumina particles (Al₂O₃), (5) tribochemical silica coating (CoJet). Following, the specimens were divided into three subgroups according to universal adhesive applied: Clearfil Universal Bond (CU; Kuraray), Prime&Bond Universal (PBU; Dentsply Sirona), or Single Bond Universal (SBU; 3M ESPE). A nanofill composite (Filtek Ultimate; 3M ESPE) was employed as a repair. Bonded specimens were stored in water for 24?h at 37?°C or thermal aged, then subjected to the μTBS test. Additionally, specimens were analyzed with a contact profilometer and were evaluated with scanning electron microscopy. Control and PA treatments were showed the lowest µTBS (p?<?0.05), and there was no significant difference between these two groups (p?>?0.05). Al₂O₃ and CoJet treatments generally exhibited a similar influence on µTBS values. In addition, a correlation was found between surface roughness and bond strength (r?=?0.831). CoJet resulted in significantly higher repair µTBS values when compared to the other surface treatments. In addition, the use of silane-containing universal adhesive was increased the cohesive failure rate and maintained the repair µTBS values after thermocycling.     

Phenolic adhesives based on eucalyptus pyrolytic oil: Effect of urea addition on synthesis and properties

The present work aimed to evaluate the effect of urea addition on the synthesis parameters and properties of phenolic adhesives produced with oil from the pyrolysis of eucalyptus wood. The adhesive formulations were synthesized according to an entirely randomized design involving two formaldehyde/demethylated oil (F/DO) molar ratios (1.4 and 1.7), three NaOH/DO molar ratios (0.9, 1.0 and 1.1) and five levels of urea (0, 5, 10, 15 and 20%), totalizing 30 formulations. The following parameters and properties were obtained: reaction time (min) and temperature (°C); solids content (%), gel time (s), viscosity (cP) and pH. Regression analysis was performed and quadratic models were adjusted for reaction conditions (time and temperature) and some adhesive properties. Synthesis reactions were more controllable in terms of reaction time in the following conditions: urea addition in levels from 5 to 15% with F/DO molar ratio of 1.7 and NaOH/DO molar ratio of 1.0.     

Hot-melt pressure-sensitive adhesives based on SIS-g-PB copolymer for transdermal delivery of hydrophilic drugs

SIS-g-PB copolymers were successfully synthesized by grafting living polybutadiene (PB) lithium macroanions onto epoxidized SIS copolymers. Their molecular structures and thermal properties were characterized by TGA, ¹H-NMR and DSC, respectively. SIS, epoxidized SIS (ESIS) and SIS-g-PB copolymers were melt-blended with tackifiers to develop hot-melt pressure-sensitive adhesives (HMPSAs), respectively (named of H-SIS, H-ESIS and H-SIS-g-PB). Their adhesive performances were measured in terms of 180° peel strength and holding power. A modified Franz type horizontal diffusion cell was used to carry out In vitro drug release experiments, in which geniposides were chosen as hydrophilic model drugs. The results showed that H-SIS-g-PB has two times as high a 180° peel strength as H-SIS. Meanwhile H-SIS-g-PB has a slightly lower drug cumulative release rate than H-ESIS. It is indicated that the PB branches not only could impart good adhesive performance to H-SIS-g-PB via improving the compatibility between the epoxidized main chains and tackifier resins but also provide release channels to hydrophilic drugs by retaining most of the epoxide groups in the SIS-g-PB copolymers.     

Effect of reinforcements at different scales on mechanical properties of epoxy adhesives and adhesive joints: a review

Improvement of the mechanical properties of adhesives and adhesive joints has been a subject of great interest in recent years. Up to now, several methods have been presented such as modifying substrate shapes, adding microparticles (MPs) and nanoparticles (NPs), and embedding micro and macrofibers in the adhesive layer. This review aims to investigate how these reinforcements of different scales in the adhesive layer influence the mechanical properties of adhesive joints and adhesives. Characteristics and applications of reinforcements are introduced in the first part. In the second part, the effects of several parameters commonly investigated by researchers on the strength, stiffness and fracture toughness improvement of polymeric materials are reviewed for reinforcements of different scales. Finally, damage mechanisms involved in increasing or decreasing the mechanical properties are reviewed and discussed.     

Bond durability of contemporary universal adhesives: effect of dentin treatments and aging

The aim of this in vitro investigation was to evaluate the effects of different dentin treatments on µTBS values of three different universal adhesives. Sixty extracted bovine incisors were used. The teeth were horizontally sectioned from the enamel-cement junction and embedded in an acrylic resin. Enamel was removed with 180-grit SiC paper to expose dentin. The exposed dentin surfaces were further polished with 600-grit SiC paper to provide a standardized smear layer. Teeth were randomly divided into three groups, according to the universal adhesives: All-Bond Universal, Single Bond Universal, and G-Bond Plus. Each group was then assigned into four subgroups, according to the dentin treatments: etch-and-rinse mode (ER), ER + 2% chlorhexidine (CHX), ER + %2.5 genipin (GE), and self-etch mode (SE). Samples were longitudinally sectioned across the bonded-interfaces to obtain resin-dentin beams. Beams were prepared from the same teeth were randomly and equally divided into two groups: immediate µTBS testing and µTBS testing after 6-month. The failure loads were recorded in MPa, and failure modes were evaluated at 30× magnification. The data were analyzed using a two-way ANOVA, to determine the effects of dentin treatment and storage time, and the interaction of these two factors on the µTBS of universal adhesives. Dentin treatments were showed significant differences (p?<?0.05). ER mode exhibited higher µTBS than SE mode. However, universal adhesives were more durable in the SE mode than ER mode. Also, chlorhexidine treatment significantly improved adhesive performance of all universal adhesives, while no significant improvement was detected with genipin treatment.     

Analysis of the nonlinear behavior of adhesives in bonded assemblies—Comparison of TAST and Arcan tests

This paper describes a study in which the shear behavior of a structural epoxy adhesive has been measured using the standard thick adherend shear test (TAST) specimen and a modified Arcan test. A numerical study of the TAST test taking into account the nonlinear behavior of the adhesive and the finite deformations of the adhesive joint, shows that there is a localization of plastic zones close to the adhesive–substrate interface near the free edge of the adhesive. Experimental tests carried out with steel and aluminum substrates and with various adhesives also show that failure initiates in this region. These edge effects in the TAST fixture can lead to an incorrect analysis of the behavior of the adhesive (for instance, underestimation of the shear stress in the joint at failure), particularly when an adhesive failure mode is dominating. The modified Arcan fixture provides a more homogeneous stress state. A similar improvement of the TAST fixture is proposed.     

不同木质素磺酸钠对豆粕胶黏剂性能的影响

通过FTIR、元素分析、GPC对4种不同来源的木质素磺酸钠进行物理化学性质分析,并将其与水性聚酰胺协同改性豆粕胶黏剂(简称豆粕胶),利用测试接触角、剪切黏度和湿态胶合强度考察改性前后胶黏剂的浸润性、流变特性以及所得胶合板的胶合性能.红外谱图分析表明,在1065 cm–1附近出现了磺酸基或磺甲基中S==O的伸缩振动吸收峰,证明木质素经过磺化反应或磺甲基化反应得到木质素磺酸钠;木质素磺酸钠中磺酸基含量越高,经其改性的豆粕胶的零剪切黏度越低且在木材表面的润湿性越好;豆粕胶黏剂与杨木单板的接触角从未改性的95°降到改性后的61°;与水性聚酰胺协同改性后的豆粕胶制得胶合板的湿态胶合强度达到0.92 MPa,合格率为100％,满足国家Ⅱ类胶合板的标准要求(胶合强度≥0.70 MPa,合格率≥90％).     

Effect of Physicochemical Surface Treatments on the Bond Strength and Adhesion of Porcelain Denture Teeth to Heat-Polymerized Acrylic Resin Denture Base Material

The aim of this study was to compare the effect of physicochemical surface treatments on the adhesive bond strength of porcelain denture teeth (PDT) to acrylic resin denture base material (PMMA). Totally, 100 PDT specimens, 50 with retentive palatal pins (+P) and 50 without pins (?P), were selected and assigned to 10 experimental groups (n = 10). Control groups CON-P and CON + P, did not receive any treatment. Groups SB + P and SB-P were sandblasted, groups SB/AE + P and SB/AE-P were sandblasted and acid-etched, groups TSC + P and TSC-P were tribochemically silica-coated, and groups FB + P and FB-P were covered with fibers. Cylindrical PMMA rods were polymerized onto treated palatal PDT surfaces. Force (N) was applied on palatal incisal edges of PDT specimens until debonding of PMMA. Obtained data were statistically analyzed with Kruskal-Wallis and Bonferroni corrected Mann Whitney U tests. The significance level was set at (p < .05). Mean force values of test groups ranged in descending order as follows: TSC+P (132.5 N ± 26.5), SB+P (113.5 N ± 47.5), SB/AE+P (112.2 N ± 26.1), CON+P (103.1 N ± 39.6), TSC-P (90.6 N ± 22.2), FB+P (77.7 N ± 18.3), SB/AE-P (47.6 N ± 10.5), SB-P (18.1 N ± 4.0), CON-P (4.6 N ± 5.4), and FB-P (0.0 N ± 0.0). No significant difference was found between groups with pins (+P) except group FB+P which displayed lower values than CON+P (p < .024), and TSC+P (p < 045). Groups (+P) showed significantly higher bond strength values than groups (?P) except for group TSC-P (p < .09 and p < 1). In groups without pins (P?), differences between groups were significant and ranged as follows: TSC-P>SB/AE-P (p < .0094), SB/AE-P > SB-P (p < .007), and SB-P > CON-P (p < .0013). Groups CON-P and FB-P did not show differences (p ≤ 1). Groups (+P) displayed higher bond strength values than groups (?P). SB-P, SB/AE-P, and TSC-P increased the adhesive bond between PDT and PMMA, respectively. Fiber coating negatively affected the bond.     

Durability of adhesives based on different epoxy/aliphatic amine networks

The mechanical and adhesives properties of epoxy formulations based on diglycidyl ether of bisphenol A cured with various aliphatic amines were evaluated in the glass state. Impact tests were used to determine the impact energy. The adhesive properties have been evaluated in terms single lap shear using steel adherends. Its durability in water at ambient temperature (24 °C) and at 80 °C has also been analyzed. The fracture mechanisms were determined by optical microscopy. It was observed a strong participation of the cohesive fracture mechanisms in all epoxy system studied. The 1-(2-aminoethyl)piperazine epoxy adhesive and piperidine epoxy adhesive presents the best adhesive strength and the largest impact energy. The durability in water causes less damage to piperidine epoxy networks. This behavior appears to be associated with the lower water uptake tendency of homopolymerised resins due to its lower hydroxyl group concentration.     

Eco-friendly denture adhesives (EFDAs) filled with different types of natural starches: mechanical and biological performance evaluation

Abstract

This research focuses on the development of eco-friendly denture adhesives (EFDAs) by studying the effects of the addition of different types of native and modified natural starches as fillers in denture adhesive properties for dental applications. The properties of EFDAs filled with single and hybrid starches in comparison with a selected commercial denture adhesive were investigated. The investigated single starches were corn, tapioca and sago while the hybrid starches used were corn/tapioca (CT), corn/sago (CS) and tapioca/sago (TS), all with ratio of 1:1. The EFDAs were prepared with 5, 10 and 15 percent (wt. %) loading of starch filler. The starches were chemically and physically modified via oxidation and gelatinization techniques. The mechanical characterization performed were tensile bonding strength (TBS), adhesiveness and hardness, as well as cytotoxicity test by using an MTT assay for biological analysis. Mechanical analysis indicated that produced EFDAs have higher tensile bond strength, adhesiveness and hardness as compared to the commercial denture adhesive. The increment was associated with the addition of hybrid starches and an optimum filler loading at 10%. The EFDAs were also non-toxic to the dental pulp stem cells (DPSC) up to 48?h. EFDA has good potential to be used as a natural based denture adhesive as it contains natural materials namely starch which enhances its properties. The properties were suitable for better denture bonding, retention and showed good interaction with the biological environment.     

Solvent presence and its impact on the lap-shear strength of SDS-decorated graphene hybrid electrically conductive adhesives

The mechanical bonding strength of electrically conductive adhesives (ECAs), as well as the impact of residual solvent on the bonding strength was investigated between a copper clad FR-4 surface and conductive adhesives using Lap-shear testing. Both solvent-free and solvent-assisted formulations with various filler concentrations of silver (Ag) and sodium dodecyl sulfate (SDS)-decorated graphene (Gr(s)) in epoxy matrices were prepared and compared. It was found that the introduction of 0.75 wt% Gr(s) in solvent-free formulations increased the Lap-shear strength (LSS), while the combination of ethanol solvent and SDS in solvent-assisted formulations significantly decreased the LSS. In addition, it was found that increasing the Ag content generally lowers the LSS for both the solvent-free and solvent-assisted formulations. By examining the structure and interface of both formulations using optical microscopy, surface profilometry and SEM, we found that the solvent-assisted formulations exhibit more voids at the surface of the paste and more bubble formation throughout the material compared to the solvent-free formulations. Therefore, the significant drops of LSS in solvent-assisted Gr(s)-filled formulations may be attributed to the formation of bubbles at the micron range during the curing process.     

Effect of citric acid,PVOH, and starch ratio on the properties of cross-linked poly(vinyl alcohol)/starch adhesives

The properties of tapioca starch adhesives were improved by cross-linking and the cross-linked adhesive compared with pure tapioca starch and poly(vinyl alcohol) adhesives. The effect of starch ratio, type of PVOH, and adding citric acid were important factors on the cross-linked adhesives. Wood adhesives made from cross-linked PVOH/starch were prepared by PVOH and tapioca starch, using hexamethoxymethyl melamine (HMMM) and citric acid (CA) as a cross-linking agent and catalyst, respectively. The effect of CA, PVOH/starch ratio, and type of PVOH such as medium (M PVOH) and high molecular weight (H PVOH) were investigated. The condition of the cross-linking reaction was 175?°C for 15?min. The structural properties of cross-linked adhesive were investigated by FT-IR spectroscopy. The results were confirmed in terms of thermal properties with a differential scanning calorimeter (DSC) and the shear strength of the adhesive. The cross-linked adhesive resulted in the increase of T _g and showed good blend compatibility with all of the cross-linked adhesives. The adhesive strength significantly increased when using CA as a catalyst in the cross-linking reaction. The optimum contents of the cross-linked PVOH/starch adhesives were 1:1.8 for M PVOH and 1:0.5 for H PVOH.     

Effectiveness of different surface cleaning methods on the shear bond strength of resin cement to contaminated zirconia: an in vitro study

The purpose of this in vitro study was to evaluate and compare the effectiveness of different surface cleaning methods on the shear bond strength (SBS) of zirconia ceramic surfaces. Seventy polished and cleaned zirconia disk specimens of 8 mm in diameter and 3.4 mm in thickness were immersed in fresh saliva. They were then pressed into a freshly mixed silicone disclosing medium. Six different cleaning methods were applied to the tested groups; they were airborne-particle abraded (AA), covered with a cleaning paste (Ivoclean®) (IV), etched with orthophosphoric acid (PA), immersed in alcohol (AL), rinsed with tap water only (WA), or cleaned with steam (SC). No surface cleaning was done after saliva immersion and silicone disclosing medium contamination to the control group (CC). The specimens were then bonded to an adhesive resin cement using polyethylene tubes. SBS was determined using a universal testing machine at a crosshead speed of 1 mm/min. The specimens were also examined with a scanning electron microscope and a stereomicroscope. Group AA yielded the highest SBS value (7.01 ± 1.4 MPa) among the groups, while Group WA had the lowest SBS value (3.03 ± 0.8 MPa). The SBS values of Group AA (7.01 ± 1.4 MPa) and IV (6.2 ± 1.7 MPa) were also significantly higher than those of the remaining four groups (p < 0.05). Within the limitations of this in vitro study, it was concluded that among the various cleaning methods tested, airborne-particle abrasion and Ivoclean® paste were effective in cleaning the zirconia surface.     

Effect of different skin permeation enhancers on peel strength of an acrylic PSA

Different amounts of two skin permeation enhancers, Oleic acid (OA) and Propylene glycol (PG), were mixed thoroughly with solution of a commercial acrylic pressure sensitive adhesive (Duro‐Tak). Films with different adhesive layer thickness (30 and 60 μm) were prepared by casting of formulations with a film applicator on a PET 80‐μm film and drying of solvents. Peel test was done on different formulations according to ASTM D3330. Surface study and thermal analysis were used for explaining the results. It was shown that the effect of interfacial work of adhesion on peel strength was too low to be considered. PG had no significant effect on peel strength, which was related to effect of hydrogen bonds between PG and copolymer chains acting as crosslinks. OA decreased peel strength significantly, which is due to important changes in copolymer structure. These changes can be found by relatively sharp drop in T_g values. Adhesive–cohesive transition occurred in OA formulations as a result of OA crystals formation. OA migration to surface in concentrations of more than 10 (w/w %) was confirmed by results of DSC and surface study. In contrast with PG, doubling of thickness had no effect on peel strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2987–2991, 2003