Adhesion Durability Research Articles

Fireproof intumescent systems modification by means of phosphorus-containing metal/carbon nanocomposites for construction applications

In the present paper, a method for modifying a copper/carbon nanocomposite with ammonium polyphosphate is considered. The optimum ratio of reagents at the modification of composite was found using infrared and X-ray photoelectron spectroscopy. Experimental tests were carried out for samples of fireproof intumescent coatings based on epoxy resins modified with the phosphorus-containing copper/carbon nanocomposites. An increase of more than 20 % in such properties as adhesive durability and fire-retardant performance for the coatings modified with the above nanocomposites was determined.

Effect of surface roughness and chemistry on the adhesion and durability of a steel-epoxy adhesive interface

This work focuses on the effect of surface roughness and surface chemistry on the initial adhesion strength and corrosive de-adhesion properties of adhesive bonds. The adherend used in this study is a S690 low-alloy steel whereas the adhesive is a 2-component epoxy-amine adhesive (Araldite 2015). The steel surface is subjected to different surface pre-treatment methods such as mechanical abrasion, grit blasting, zirconium conversion treatment and silane treatment. The effect of these different pre-treatments on the surface morphology, roughness and chemistry is addressed. Single-lap joint tests were performed at ambient conditions to assess the initial bond strength of the joint. Static wedge tests were performed in saltwater immersions to study the environmental ageing of the adhesive joints. Unloaded delamination of adhesive films from the steel surface was studied by means of scanning Kelvin probe (SKP) at high relative humidity. This unique combination of different techniques allows thorough evaluations of the bond performance under different environmental and loading conditions. Experimental results indicate that surface roughening plays an important role in the initial adhesion in the single-lap joint test but a minor role in the durability of the bonded steel surfaces. The improved initial adhesion is mainly attributed to the increased interfacial bond area at higher surface roughness. The presence of complex texture or morphology shows a more profound effect than the average roughness on both the initial adhesion and the durability of the interfacial adhesion. The results from the static wedge test show the large contribution of mechanical interlocking, caused by texturing of the surface, on the durability of the interfacial adhesion. In the absence of complex texture, surfaces with altered chemistry by zirconium- or silane treatment exhibit a significant increase of the initial bonding strength due to enhanced physicochemical interactions across the interface. Assessment of the interfacial delamination kinetics by SKP show that despite the absence of any surface topography, chemically altered surfaces prove to have higher resistance to delamination.

Determination of residual strain in steel wire cord by chemical method

The article presents a method for determining the residual strain in the steel wire cord of construction 3x0,30. The causes of residual strain, the effect on the quality of finished product and the determination of the degree of residual strain by chemical method are considered. The cause of residual strain is uneven plastic deformation of a solid body due to various changes in different places of its length and volume. Residual strain of steel wire cord are made up of stresses existing in the wire after drawing, and the stresses created during the lay of wire.An important task in the framework of the metal wire cord manufacturing technology, which is faced by specialists at «BMW» – the Management Company of the Holding «BMC» is to reduce residual strains at all stages of metal wire cord manufacturing. Residual strains are an additional factor affecting the adhesive strength and durability of adhesive joints.The principle of determining the residual strains is to remove the coating from the metal wire cord, paint the transverse halves of each thread. Then the filaments are impregnated with nitric acid, and the residual strain on the surface is recorded as the difference between the residual strains of the two halves of the wire.

Exploring Manufacturing Process and Degradation Products of Gilt and Painted Leather

In this work, we studied the manufacturing processes and the conservation state of gilt and painted leather fragments from Palazzo Chigi in Ariccia (Italy) by using different analytical techniques. Leather fragments present a silver leaf superimposed onto leather support. A gold varnish and different painted layers decorate it all. A top-down analytical approach was used to investigate this complex multilayer structure, which adopted techniques with different sampling depths. Organic and inorganic constitutive materials together with related degradation products were studied by time of flight secondary ion mass spectrometry (ToF-SIMS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and macro X-ray fluorescence (MA-XRF). The findings have revealed the presence of different elements and species as calcium and iron in the leather support, which was attributed to the un-hairing process in the leather tanning. Regarding what concerns the silver leaf, where the varnish cracked, silver chlorides, oxides, and sulfides were detected as degradation products of the silver leaf. Proteinaceous compounds were also identified where the silver leaf is unprotected by the varnish. These ion signals reveal a potential use of animal glue on both sides of the silver leaf to promote durable adhesion. In the gold varnish, the surface analysis revealed organic compounds such as resins and oils. In particular, the copresence of linoleic, arachidonic, and lignoceric acid ion signals in the yellow area suggests the use of aloe as a colorant. Lead ions in the same area were detected and attributed to the use of lead as siccative. Blue areas were obtained by using indigo and lead white in addition to an oil binder. This is confirmed by the detection of indigotin, fatty acid, and lead soap ion signals. A copper-based pigment was used to depict the green areas and copper oxalates were identified as its degradation products. Lastly, no significant information about the red colorant was obtained. Colophony is present as a component of the final varnish.

Influence of phosphoric acid etching on the dentin bond durability of universal adhesives

This study aimed to compare the microshear bond strength (MSBS) of three universal adhesives and a three-step conventional adhesive to dentin after 24-hour and one-year storage in water. A new fluoride-releasing universal adhesive (Clearfil Universal Bond Quick: CUQ) and two commercially available adhesives (ScotchBond Universal: SBU and All-Bond Universal: ABU) were evaluated with phosphoric acid etching (PA-etch mode) or without it (self-etch mode). All-Bond 3 (AB3) served as control group. After bonding composite cylinders to dentin discs obtained from caries-free human teeth, the specimens were stored in deionized water at 37 °C for either 24 hours or one year (n = 14) before MSBS measurement. Two-way ANOVA analysis of the results showed that the adhesives, storage time and their interactions had a significant effect on MSBS (p < 0.01). In self-etch mode, there was no significant difference among universal adhesives at the baseline. In PA-etch, the CUQ and SBU showed significantly higher MSBS compared with AB3 (p < 0.05). At baseline, no difference was found between the two modes for each universal adhesive (p > 0.05). After one year, CUQ in self-etch mode showed a slight increase in nominal MSBS (p > 0.05) and Weibull characteristic strength, which was significantly higher than SBU and ABU in the corresponding mode. There was no difference among the three universal adhesives in PA-etch mode after one year (p > 0.05). In conclusion, the durability and reliability of dentin bonding with universal adhesives in different application modes depended on the material; and the self-etch approach showed promising results for the tested fluoride-releasing universal adhesive.

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.

Enamel Etching for Universal Adhesives: Examination of Enamel Etching Protocols for Optimization of Bonding Effectiveness.

The purpose of this study was to evaluate whether different enamel etching methods with reduced etching times would improve the bonding effectiveness of universal adhesives. Three enamel etching methods, phosphoric acid ester monomer (PPM) etching, phosphoric acid (PPA) etching, and polyalkenoic acid (PLA) etching, and three universal adhesives, G-Premio Bond (GP), Prime&Bond elect (PE), and Scotchbond Universal Adhesive (SU), were evaluated. Initial bond strengths and fatigue strengths of universal adhesives to ground enamel and ground enamel etched for less than one, five, 10, and 15 seconds using different etching methods were determined. The bonded fatigue specimens were loaded using a sine wave at a frequency of 20 Hz for 50,000 cycles or until failure occurred with a staircase method. Atomic force micrograph (AFM) observations along with measurements of surface Ra roughness and modified surface area of enamel with different etching protocols were also conducted. The bond fatigue durability of universal adhesives to enamel with PPA etching from less than one to 15 seconds and PLA etching for 15 seconds was significantly higher than that to ground enamel. The bond fatigue durability to enamel with PPM etching was not increased compared with ground enamel. The surface Ra roughness and surface area obtained with AFM of enamel increased after PPA and PLA etching, and those values were significantly higher than those of ground enamel. Furthermore, surface Ra roughness and surface area with PPA etching were significantly higher than those with PLA etching. However, surface Ra roughness and surface area of enamel with PPM etching were similar to those of ground enamel regardless of etching time. PPA etching for less than one to 15 seconds and PLA etching for 15 seconds improve universal adhesive bonding, surface Ra roughness, and surface area of enamel. However, PPM etching is not effective, regardless of etching time, in improving bonds strengths, increasing surface roughness, and increasing surface area.

Adhesion durability of dual-cure resin cements and acid–base resistant zone formation on human dentin

ObjectivesBond durability and resistance to acid-base challenge of dentin with dual-cure resin cement have been rarely investigated. The purpose of this study was to evaluate dentin bond strength and observe the adhesive-dentin interface after acid-base challenge using three different dual-cure resin cements. MethodsThirty dentin surfaces from caries-free human premolars were ground and bonded with one of three dual-cure resin cements: PANAVIA V5 (V5), ESTECEM II (E II) and Rely X Ultimate (RXU) and thermocycled for 0, 5,000 and 10,000 cycles. A microtensile bond strength (μTBS) test was undertaken and the interface of the bonded specimens after acid-base challenge was examined by SEM. ResultsThe μTBS of V5 exhibited a stable bond strength despite thermal cycling while the bond of EII and RXU after 10,000 cycles dropped significantly among all thermal cycle periods (p<0.05). An acid-base resistant zone (ABRZ) was observed in all groups, however, the morphology of the bonded interface differed among the tested cements. ConclusionBonding durability to dentin and ABRZ morphologies differed among the cements evaluated. PANAVIA V5 cement system with tooth primer provided the most reliable bond strength and was best able to resist the acid–base challenge.

SEM-EDS nanoleakage evaluation of universal-adhesive-systems with etch-and-rinse and self-etch approach

Introduction: For adhesive systems to be considered efficient they should maintain restorations stable and with adherence. They also should be capable to seal restorations margins against oral fluids and microorganisms for a long period [1,2]. Adhesive interface permeability to water and other oral fluids is possible even in restorations without detectable pores since their entry can be done through nanometric defects [2,3]. This adhesive interface degradation by hydrolysis can negatively affect adhesion durability leading to an adhesive interface degradation, process that Sano in 1995, called nanoleakage [4,5]. The aim of this study was the nanoleakage evaluation of universal adhesive systems, by SEM-EDS with Etch-and-rinse and Self-Etch approach. Materials and methods: This work was approved by the IUEM Ethics Committee. 24 intact human molars extracted for orthodontic or periodontal reasons were randomly divided into 12 groups (n = 2), 6 control and 6 experimental. Three universal adhesive systems, Futurabond® U, Prime & Bond® Active™ and Scotchbond™ Universal, were tested in their etch-and-rinse and self-etch approaches. Teeth were cut in a hard tissues microtome to expose superficial dentin and were polished with a 400 grit SiC paper. Adhesives were applied according to manufacturer’s instructions and resin build-ups were obtained with Filtek Z250 resin (colour A2) with 2 mm increments up to a maximum of 6–8 mm. Samples were sectioned in the X direction on a hard tissue microtome in order to obtain slices of 0.7 mm. 10 slices were selected for each group. In the control groups samples were stored in 5 ml of oil (VV Lubricant) for 3 months in an oven at 37 °C in order to avoid the hydrolytic degradation process and the experimental groups were stored in 5 ml of deionized water for 3 months in an oven at 37 °C so that it was possible to observe the hydrolytic degradation. After the incubation period samples were prepared and subjected to SEM-EDS nanoleakage tests. Statistical analyses with a Mixed Linear Model (MM), with Akaike (AIC), Hurvich andTsai (AICC), Bozdogan (CAIC) and the Bayes and Schwarz (BIC) information criteria were done. Results: No significant differences were found between universal adhesives. However, there was a significant difference concerning the adhesion strategy. The previous acid conditioning caused a greater expression of the nanoleakage. Discussion and conclusions: In our study we verify that when universal adhesives were applied with the etch-and-rinse approach the adhesive interface percentage infiltrated with silver nitrate is significantly higher that when adhesives were applied in the self-etch approach. These results are in accordance with other studies found in literature. Marchesi et al. [6] observed that nanoinfiltration was significantly reduced when Scotchbond Universal adhesive was applied as self-etch. In another study Luque-Martinez et al. [7] studied three universal adhesives: Scotchbond Universal, All-Bond Universal e Prime&Bond Elect and found that all presented significantly higher nanoinfiltration when applied as etch & rinse. The same results were found by Muñoz et al. [8] for the All-Bond Universal and G-Bond adhesives. The self-etch application of these universal adhesives seemed to contribute to the stability and durability of the adhesive interface.

Six months evaluation of posterior occlusal restorations with five adhesive systems: results from a randomized controlled trial

Introduction: Resin-based direct posterior restorations are routine and well-established procedures in dental practice [1,2]. Durable adhesion to enamel and dentin is a fundamental prerequisite to prevent premature marginal breakdown of the restorations. All contemporary adhesive systems contain multiple and specific molecules in their formulation that meet identical functions, thereby sharing the same basic bonding mechanism. However, molecule chemistry, specificity, proportion of the incorporated ingredients and their interaction with different tooth structures varies greatly between adhesive systems with impact on the quality of the bond provided by each system [3]. Available evidence is still quantitatively and qualitatively insufficient to indicate the most adequate adhesive strategy to use in posterior load-bearing lesions [4]. The aim of this randomized clinical trial was to evaluate the efficacy of different adhesive systems in the restoration of occlusal cavities over the course of six months (6M). Materials and methods: The protocol and consent form for this study were reviewed and approved by the Ethics Committee (CHUC-15-09). The study enrolled 54 patients and evaluated the performance of two etch-and-rinse (Optibond™FL (G1), Prime&Bond®NT™ (G2)) and three self-etch (Clearfil™SE Bond (G3), Xeno®III (G4), Xeno®V+ (G5)) adhesive systems on 159 posterior resin composite restorations (G1 = 32; G2 = 32; G3 = 32; G4 = 31; G5 = 32). The selected teeth were distributed following a block randomization list with block sizes of 5 corresponding to the 5 possible treatments to ensure group consistency during recruitment. Allocation of the adhesives was revealed to the operator after cavity preparation by opening of a sealed envelope. The operator was not blinded to group assignment due to differences in the application protocol of the materials. Patients and evaluators were blinded to group assignment. Restorations were evaluated using the World Dental Federation (FDI) criteria and the study was reported according to the CONSORT statement. Statistical analysis was performed with Friedman-test for paired samples and inter-group analysis with Mann-Whitney test (p < 0.05). Results: At 6 months, 49 patients attended the follow-up and 144 restorations were evaluated (G1 = 29; G2 = 28; G3 = 30; G4 = 28; G5 = 29). Among aesthetic properties, only surface staining showed statistical significant alterations from baseline (BL) to 6M in G1, G3, G4 and G5 (p < 0.05) reporting variations from score 1 to score 2. Regarding biological criteria, no significant alterations could be found. Considering functional properties, a statistically significant decrease in the number of restorations with marginal adaptation occurred for the self-etch adhesives (G3, G4 and G5), but changes were only registered from score 1 to score 2 (p < 0.01). Marginal adaptation was the only parameter with statistical significance regarding group comparison. Pairwise comparisons indicated that etch-and-rinse adhesives presented statistically better performance than any other of the self-etch systems at 6 months (p < 0.01). Discussion and conclusions: Several studies using self-etch adhesives in posterior restorations indicate that marginal integrity is the parameter most negatively affected, which is in accordance with the present study [4,5,6]. The poorer enamel bonds provided by self-etch adhesive systems may be responsible for the premature loss of integrity of the margins. Nevertheless, at six months of follow-up all cases were successful and clinically considered no less than satisfactory. (Clinical Trial Registration number: ISRCTN87835631)

Using a butt joint test to evaluate photovoltaic edge seal adhesion

AbstractMany photovoltaic (PV) technologies have been found to be sensitive to moisture that diffuses into a PV package. Even with the use of impermeable frontsheets and backsheets, moisture can penetrate from the edges of a module. To limit this moisture ingress pathway from occurring, manufacturers often use a low permeability polyisobutylene (PIB)‐based edge seal filled with desiccant to further restrict moisture ingress. Moisture ingress studies have shown that these materials are capable of blocking moisture for the 25‐year life of a module; but to do so, they must remain well‐adhered and free of cracks. This work investigates the potential use of a butt joint test for evaluating the long‐term durability of adhesion by looking for significant changes in the failure mode or quantitative value of a butt joint test. A round robin experiment was conducted using six different materials and two sample constructions, with and without effort to control edge pinch. Tests were evaluated looking at the strength of the bond, and the type of failure observed in a round robin test involving five laboratories. It was found that both the measured values, and the observed failure modes were repeatable and reproducible within at 95% confidence interval.

Influence of silver nanoparticles on resin-dentin bond strength durability in a self-etch and an etch-and-rinse adhesive system

ObjectivesThis study evaluated the effect of dentin pretreatment with silver nanoparticles (SNPs) and chlorhexidine (CHX) on the microshear bond strength (µSBS) durability of different adhesives to dentin.Materials and MethodsOcclusal surfaces of 120 human molars were ground to expose flat dentin surfaces. The specimens were randomly assigned to six groups (n = 20). Three groups (A, B, and C) were bonded with Adper Single Bond 2 (SB) and the other groups (D, E, and F) were bonded with Clearfil SE Bond (SEB). Dentin was pretreated with CHX in groups B and E, and with SNPs in groups C and F. The specimens were restored with Z250 composite. Half of the bonded surfaces in each group underwent µSBS testing after 24 hours and the other half was tested after 6 months of water storage.ResultsSNP application was associated with a higher µSBS than was observed in the CHX and control groups for SEB after 24 hours (p < 0.05). A significantly lower µSBS was observed when no dentin pretreatment was applied compared to dentin pretreatment with CHX and SNPs for SB after 24 hours (p < 0.05). The µSBS values of the 6-month specimens were significantly lower than those obtained from the 24-hour specimens for all groups (p < 0.05). This decrease was much more pronounced when both adhesives were used without any dentin pretreatment (p < 0.05).ConclusionsSNPs and CHX reduced the degradation of resin-dentin bonds over a 6-month period for both adhesive systems.

Universal Adhesives Benefit from an Extra Hydrophobic Adhesive Layer When Light Cured Beforehand.

To measure microtensile bond strength (μTBS) of universal adhesives immediately and after 6-month aging, with or without an additional adhesive layer applied on a separately light-cured or non-light-cured universal adhesive. Eighty human third molars were randomly assigned to 8 experimental groups. The universal adhesives Clearfil Universal Bond (Kuraray Noritake) and Single Bond Universal (3M Oral Care) were used in self-etch mode (following the manufacturer's directions), and either light cured or not before application of an extra hydrophobic adhesive layer (Clearfil SE Bond bond, Kuraray Noritake). The two-step self-etch adhesives Clearfil SE Bond (Kuraray Noritake) and OptiBond XTR (Kerr) were used as references. After composite buildups were bonded to mid-coronal occlusal dentin surfaces, the specimens were stored in water (37°C/24 h) and sectioned into microspecimens (0.96 ± 0.04 mm2). Half of the specimens were immediately subjected to μTBS testing (1.0 mm/min), while the other half was stored in water (37°C) for 6 months prior to testing. Failure analysis was performed using stereomicroscopy and SEM. Data were analyzed with two-way repeated measures ANOVA, Tukey's and paired t-tests (p = 0.05). The immediate μTBS was similar for the universal adhesives when applied following the different application strategies (p > 0.05). Application of an extra layer of hydrophobic adhesive improved the aged μTBS of the universal adhesives, which was statistically significant when the universal adhesives were first light cured (p < 0.05). The reference adhesives Clearfil SE Bond and OptiBond XTR exhibited a significantly higher immediate and aged μTBS to dentin than did the universal adhesives (p < 0.05). The bond durability of universal adhesives, applied in self-etch mode, was found to benefit from the application of an extra hydrophobic adhesive layer when the universal adhesives were first light cured.

In vitro Study of the Structure and Adhesive Interface in Direct Restorations with Experimental Nanocomposite Materials and Adhesive Systems

Using nanotechnology to produce composite materials it has been possible to obtain materials with similar or better mechanical properties than previous generation of microhybrids, and with exceptional aesthetics and chandelier due to the particularities of nanomaterials. At the same time, the improvement of adhesive techniques to enamel and dentin allowed the expansion of the area of direct composite restorations with a better prognostic over time.Eight carie-free molars were used and each of them was prepared with two class II cavities, which were filled using the C13 and C20 nanocomposites and the A1 and A2 experimental adhesive systems prepared at the Raluca Ripan Chemistry Research Institute. The teeth were divided into four groups of two teeth each, depending on the adhesive system and the composite material used. Scanning electron microscopy images (SEM) have described the adhesive interface and structure characteristics for the two nanocomposite materials and for the two studied adhesive systems.The studied nanocomposites have a variable number of porosities and air bubbles, with a clinical importance which is yet hard to establish.The experimental adhesives used produce a good interface and infiltration of the smear-layer but have not been visualized inside the dentinal canals.In vitro studies are necessary to evaluate the durability of adhesion in the case of self-etch adhesives in one or two steps.

PDA-assisted one-pot fabrication of bioinspired filter paper for oil–water separation

Inspired by the robust and durable adhesion of mussels, highly hydrophobic filter paper was fabricated by a polydopamine (PDA)-assisted one-pot procedure using silica nanoparticles and silane coupling agent (hexadecyltrimethoxysilane, HDTMS) as coating materials at ambient temperature. The surface chemistry, morphology, and hydrophobicity of the coated filter paper were measured by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscope, scanning electron microscopy, and water contact angle. The capacity, durability, and recyclability of the coated filter paper were evaluated by the separation of oil–water mixtures and emulsions. The coated filter paper is highly hydrophobic with a water contact angle of > 130°. The coatings with enhanced adhesion to the substrate resisted mechanical abrasion without significant loss of hydrophobicity, which suggested that PDA plays a crucial role in improving the adhesion of silica nanoparticles to the paper surface. The coated filter paper showed high oil–water separation efficiency up to 95%, and maintained high hydrophobicity after recycling over 10 cycles. The coated filter paper that is based on a simple, low cost, and environmentally friendly procedure exhibits potential for applications in oil-recovery and oil–water separation materials.

Bond strength of three different universal adhesives after different thermal cycling protocols

The purpose of this study was to examine the bond strength of three different universal adhesives on enamel after different aging periods. Ninety enamel specimens were prepared and randomly assigned into three groups according to different universal adhesive systems (n = 30): iBOND Universal (IB), G-Premio Bond (GP), Clearfil Universal Bond Quick (CU). All adhesives were applied at etch&rinse mode. A cylinder-shaped resin composite was placed on enamel surfaces and light cured. Then all specimens were stored in distilled water at 37 °C for 24 h and divided into 3 thermal cycling protocol groups (n = 10): No thermal cycling (NTC), 10,000 thermal cycles (10TC), 40,000 thermal cycles (40TC). Specimens were subjected to shear bond strength (SBS) test at a universal testing machine. Failure modes were determined and SEM analyses were performed for each failure mode. Data were analyzed using two-way ANOVA followed by Tukey HSD test. The highest SBS values were observed at NTC groups. The 40TC groups showed significantly lower SBS values than other groups (p < 0.05). The highest mean SBS values were obtained in IB at NTC group (p < 0.05). After 10TC, all universal adhesives exhibited similar SBS values (p > 0.05), however after 40TC, CU showed higher SBS than GP. The mean shear bond strength to enamel was significantly affected by thermal cycling (p < 0.05). The enamel bond durability of universal adhesives dractically decreased after 10,000 and 40,000 thermal cycling periods. The universal adhesives tested showed different SBS values at NTC and after 40TC.

Do collagen cross-linkers improve dentin’s bonding receptiveness?

ObjectivesDentin biomodification using collagen cross-linkers has been proposed as one of the strategies to improve bond durability of adhesives to dentin. However, literature is not very consistent regarding their benefit, in particular when cross-linkers are applied in clinically realistic application times. This study investigated the effect of three cross-linkers on the mini-interfacial fracture toughness (mini-iFT) of four adhesives bonded to dentin following either etch&rinse (E&R) or self-etch (SE) modes. Methods60 molars were randomly divided in accordance with the three variables: cross-linker, adhesive and bonding mode (n=5). The cross-linkers glutaraldehyde (5wt%; GA), proanthocyanidin (6.5wt%; PA), or UVA-activated riboflavin (0.5wt%; RB), and distilled water (control) were applied on dentin for 60s after acid-etching (E&R) or before self-etching (SE). The 3-step E&R adhesive (3E&Ra) OptiBond FL (Kerr), the 2-step SE adhesive (2SEa) Clearfil SE Bond 2 (Kuraray Noritake) and the universal adhesives G-Premio Bond (GC) and Prime&Bond Active (Dentsply), the latter two employed in both E&R and SE modes, were applied following the respective manufacturer’s instructions. Composite buildups (8×8×8mm) were made using Filtek Supreme XTE (3M) prior to 1-week storage in artificial saliva. After the teeth were sectioned into mini-specimens (1.5×2.0×18mm), a single notch was prepared at the adhesive–dentin interface. Half of the specimens were immediately loaded until failure by 4-point bending to determine the mini-iFT, while the remaining specimen set was tested upon 6-month aging. Data were statistically analyzed with a linear model (p<0.05). ResultsNo significant decrease in mini-iFT was noted only for PA (p<0.05), while the mini-iFT decreased for both other cross-linkers and in quite a similar way as when solely water (Wa) was applied. SignificanceThe cross-linker proanthocyanidin (PA) applied in clinically relevant conditions was able to maintain a stable mini-iFT after 6-month aging. The incorporation of UVA-activated riboflavin (RB) and glutaraldehyde (GA) in the dentin-bonding protocol appeared not effective to improve the stability of adhesive–dentin interfaces.

Multipurpose and Durable Adhesive Hydrogel Assisted by Adenine and Uracil from Ribonucleic Acid.

Nucleobase pairs of adenine and uracil (A-U) from ribonucleic acid are of particular interest for various promising material properties. Herein, a novel polyacrylamide hydrogel with adhesive properties that are assisted by adenine and uracil has been designed and investigated. The incorporation of adenine and uracil enables the formation of a polyacrylamide hydrogel with remarkable adhesive behaviour with various materials including polytetrafluoroethylene (PTFE), plastics, rubber, glasses, metal, ceramics and wood. Moreover, the adhesive hydrogel can easily and directly adhere to humid biological tissues without any extra process, including heart, liver, spleen, lung, kidney, bone and muscle of mouse. More impressively, even after repeated peeling tests (10×), the AU-mediated polyacrylamide hydrogel still exhibits excellent durable adhesion for various materials. From mechanical contact tests, the adhesion energy of the A-U adhesive hydrogel is 47.9 J m-2 , which is nearly nine times that of polyacrylamide hydrogel (5.3 J m-2 ). The 90° peeling strength for aluminium, titanium, silica rubbers, glasses, PTFE and hogskin is 518, 645, 445, 396, 349, and 119 N m-1 , respectively. The multipurpose and durable adhesive behaviour of hydrogels assisted by adenine and uracil indicated the promise of nucleobase pairs from ribonucleic acid for the future development of adhesive materials.

Effect of Active Application on Bond Durability of Universal Adhesives.

The purpose of this study was to determine the effect of different adhesive application methods and etching modes on the dentin bond durability of universal adhesives under thermal cycling (TC). All-Bond Universal (Bisco), Adhese Universal (Ivoclar Vivadent), and Scotchbond Universal (3M ESPE) were used as adhesives. In total, 600 bovine teeth with exposed dentin were divided into 12 groups according to the type of adhesive and subjected to the following bonding procedures: 1) etch-and-rinse mode with active application; 2) etch-and-rinse mode with inactive application; 3) self-etch mode with active application; and 4) self-etch mode with inactive application. Bonded specimens were stored in distilled water at 37°C for 24 hours and then subjected to 5000, 10,000, 30,000, or 50,000 TC between 5°C and 55°C before shear bond strength (SBS) testing, creating a division into a total of five different storage conditions. Baseline specimens were stored in distilled water at 37°C for 24 hours. The SBS test was performed at a cross-head speed of 1.0 mm/min. Three-way analysis of variance revealed that all the factors of application mode, adhesive, and thermal cycle period significantly influenced the SBS values ( p<0.001), regardless of the etching mode. In the baseline groups, all of the tested adhesives with active application had higher SBS values than those with inactive application, regardless of etching mode. In the TC groups, significantly lower SBS values were observed at 50,000 TC with inactive application compared to those with active application, regardless of the etching mode. From the scanning electron microscopy observation of demineralized and deproteinized resin/dentin interfaces, dense resin tags longer than 50 μm were observed in the etch-and-rinse with active application group. On the other hand, the resin tags in self-etch mode were sparse, thin, and much shorter than those in etch-and-rinse mode. Comparing the penetration status of the resin tags with active and inactive application in self-etch mode, the resin tag penetration with inactive application was much lower than that with active application. Active application is effective in enhancing the dentin bond durability of universal adhesives. When using universal adhesives with different etching modes, practitioners should select the optimal etching mode and appropriate application method in accordance with the cavity conditions.

The Implications of Durability, Resilience and Energy Efficiency on the Advancement of Water Management in Wall Assemblies

Abstract As building, energy, and green codes become more stringent, new building technologies and innovations are being incorporated into the building envelope. When incorporating new technologies into building assemblies, traditional construction practices need to be adapted. However, as these adaptations of construction practices take place, they still need to maintain adherence to basic principles of water management to prevent moisture accumulation in building assemblies. A critical component of water management is water-resistive barriers. Water-resistive barriers are used in light-frame wall assemblies behind the cladding to control the ingress of water, which penetrates the cladding, and keep it from penetrating further into the wall. Traditional water-resistive barriers were asphalt-impregnated papers and felts, which were applied in shingle fashion over the wall studs or sheathing. Plastic building wraps have to a large extent replaced the traditional building papers, comprising 75 % of the U.S. housing market. Recently, new materials being used as water-resistive barriers include panel materials and fluid-applied coatings. Assessing the durability of water-resistive barriers has been complicated by this range of material types. Because of the shingle-fashion installation, durability assessment of traditional materials and building wraps has focused on the material durability. The new materials require additional durability assessments relating to compatibility and durability of adhesion, most importantly at panel and substrate joints. This article describes the framework for evaluating water-resistive barrier durability.