Adhesive Technology Research Articles

The Art and Science of the Direct Posterior Restoration: Recreating Form, Color, and Translucency

In the past two decades the major advances bonding has experienced are directly related to material improvements and significant advances in adhesive technology. It is because of the superior physical properties of the posterior composite that we can provide patients with a long-lasting restoration if a meticulous bonding protocol was followed. It is possible simultaneously to preserve healthy tooth structure; reproduce its original shape, color, and translucency; and strengthen the affected tooth. Although the main focus in the past was on improving the bonding adhesive properties and the development of strength and polishability of the restorative materials, the current objective is to simplify the bonding technique and to create a shrinkage-free composite while simultaneously improving its optical properties.

Monoblocks in Root Canals: A Hypothetical or a Tangible Goal

The term monoblock has become familiar in the endodontic literature with recent interest in the application of dentin adhesive technology to endodontics. Endodontic monoblocks have generated controversial discussions among academicians and clinicians as to whether they are able to improve the quality of seal in root fillings and to strengthen roots. This review attempts to provide a broader meaning to the term monoblock and to see how this definition may be applied to the materials that have been used in the past and present for rehabilitation of the root canal space. The potential of currently available bondable materials to achieve mechanically homogeneous units with root dentin is then discussed in relation to the classical concept in which the term monoblock was first employed in restorative dentistry and subsequently in endodontics.

Partially adhesive fixation of reconstruction plates at midfacial fractures – an alternative solution to screw fixation?

AbstractFor the prognosis and long‐term stability of an implant, for example a hip‐ or knee‐implant, the anchorage to the bone is of critical importance. Normally for this anchorage bone cement is used, which achieves sufficient retention to spongious bone structure. If there is the need for osteosynthesis of midfacial fractures for surgical therapy, in some situations it would be clinically preferable to fix the reconstruction plates without the usual system using screws. This is the aim of the new adhesive fixing technology which is presented in this article. The structure of bone in midface, however, is cortical and such a smooth surface will allow only insufficient retention forces between bone and bone cement. In order to obtain a good adhesion at cortical bone nevertheless, we have to apply a bone bonding agent similar to techniques used in dentistry, which are based on dentin bonding agents, because there are different wetting properties of the hydrophilic bone and the hydrophobic bone cement monomers.Determination of achievable bond strength was done in a tension test ex vivo. Reconstruction plates were fixed with bone cement at bovine bone conditioned with a bone bonding agent developed for this field of application. With bond strengths up to 6 MPa it is assumed that an adhesive fixation of reconstruction plates at cortical bone structure is possible using the developed amphiphilic bone bonding agent.

Reliability aspects of electronics packaging technology using anisotropic conductive adhesives

Anisotropic conductive adhesive technology for electronics packaging and interconnect application has significantly been developed during the last few years. It is time to make a summary of what has been done in this field. The present paper reviews the technology development, especially from the reliability point of view. It is pointed out that anisotropic conductive adhesives are now widely used in many applications and the reliability data and models have been developed to a large extent for anisotropic conductive adhesives in various applications.

Tissue adhesion technology with integrated low level energies

Tissue adhesion technology with integrated low level energies

Adhesive Dentistry and Endodontics. Part 2: Bonding in the Root Canal System—The Promise and the Problems: A Review

One of the recent trends in endodontics has been the development of bonded obturating materials, in an effort to provide a more effective seal coronally and apically. Materials utilizing dentin adhesive technology have been borrowed from restorative dentistry and adapted to obturating materials. This review discusses the obstacles to effective bonding in the root canal system, the progress that has been made, and possible strategies for improved materials in the future. Much of the literature reviewed and many of the principles discussed are taken from the restorative dentistry literature and applied to the unique environment of the root canal system.

Comparison of bonding procedures for 3D-structured polyimide films on silicon substrates applied to ink-jet cartridges

Established bubble-jet printheads consist of an assembly of three layers, which are a CMOS substrate, a channel layer and a nozzle layer. The aim of the presented work was to simplify the setup of bubble-jet printheads by means of integrating channel and nozzle structures in one single three-dimensional laser-structured polyimide nozzle plate. Different bonding techniques for an assembly onto 1/3 inch standard CMOS printhead substrates are validated. The main challenges are a variety of bonding materials, an alignment accuracy of <5 μm and the prevention of blocking the 20 μm deep fluidic channels in the polyimide which have minimal lateral dimensions of 10 μm and a minimal pitch of 15 μm. In total, three bonding techniques, with and without additional adhesion layers, were developed and evaluated. One method applies a 4 μm thick layer of Epotec 353ND (Polytec), a standard two-component epoxy, in a specifically adapted rolling manner onto the film that is subsequently aligned to the silicon chip using a flip-chip-bonder. Screen-printing and dispensing processes of adhesives were investigated but failed due to insufficient structural resolution. The second method uses photolithographic processes to produce structured adhesion preforms in SU-8 resist. With a layer thickness of 3 μm and an adapted curing schedule, promising results concerning resolution and contour accuracy were obtained. Thirdly, bonding without additional adhesion layers was achieved in a micro-sealing process that takes advantage of the highly defined thermoplastic softening of polyimide KJ (DuPont). The different processes were compared regarding to yield, printing behavior of the assembled printheads and applicability to high volume productions. The hereby developed adhesion technology was applied on the assembly of large one inch printheads for special applications.

Comparison of microshear bond strengths of four self‐etching bonding systems to enamel using two test methods

Recent advances in enamel and dentine adhesive technology have resulted in the emergence of many new adhesive systems. Self-etching bonding systems do not require a separate etching step and the newest systems are the "all-in-one" systems which combine etching, priming and bonding into a single application. This study reports laboratory enamel microshear bond strengths of a self-etching priming and three all-in-one systems and also evaluates two different microshear bond test methods. One hundred and nineteen enamel specimens were bonded (0.8 mm diameter) with either Clearfil Protect Bond (Kuraray), Xeno III (Dentsply), G Bond (GC) or One-Up Bond F (Tokuyama) using Palfique Estelite resin composite and stored in 37 degrees Celsius water for seven days. The microshear bond test method used either a blade or wire to apply the shear stress. Results were analysed with one-way ANOVA and post hoc (Tukey) multiple comparison analysis. Clearfil Protect Bond demonstrated higher and more consistent bond strengths than Xeno III, G Bond or One-Up Bond F. The wire method showed much greater reliability in results, with a coefficient of variation half that of the blade method. All-in-one adhesives seem to be less reliable than the two-step self-etching priming adhesive when bonding to enamel. Test method can significantly affect results in the microshear bond test method.

Adhesive Technology for Restorative Dentistry

Adhesive Technology for Restorative Dentistry

Importance of Surface Tension Characterization for Food, Pharmaceutical and Packaging Products: A Review

This article reviews the various theoretical approaches that have been developed for determination of the surface tension of solids, and the applications to food industrial products. The surface tension of a solid is a characteristic of surface properties and interfacial interactions such as adsorption, wetting or adhesion. The knowledge of surface tension is thus of great interest for every domain involved in understanding these mechanisms, which recover a lot of industrial investigations. Indeed, it is the case for the packaging industry, the food materials science, the biomedical applications and the pharmaceutical products, cleaning, adhesive technology, painting, coating and more generally all fields in relation with wettability of their systems. There is however no direct method for measurements of surface tension of solids, except the contact angle measurements combined with an appropriate theoretical approach are indirect methods for estimation of surface tension of solids. Moreover, since the publication by Young (1805) who developed the basis of the theory of contact angle some two hundred years ago, measurements and interpretations are still discussed in scientific literature, pointing out the need to better understand the fundamental mechanisms of solid-liquid interfacial interactions. Applications of surface tension characterization in the field of food materials science are detailed, especially for packaging and coating applications, which recover different actual orientations in order to improve process and quality.

Failure prevention in bonded joints on primary load bearing structures

Adhesive bonding is a particularly effective method of assembling complex structures, especially those made from different materials. Provided the joint is well designed, the adhesive bond ought to be one of the strongest aspects of the structure and most certainly should not be the life limiting factor. This of course pre-supposes that the joint has been correctly executed. The major factors determining the integrity of an adhesive bond are selection of the most appropriate adhesive, joint design, preparation of the bonding surfaces, strict quality control in production and condition monitoring in service. Adhesives have become increasingly important in assembling many of the multi-material structures which make up a contemporary Formula 1 racing car. Structural fibre reinforced composite materials were introduced into Formula 1 motor racing in 1980. Since then the cars have become increasingly dependent on these materials such that the weight of a state-of-the-art chassis may consist of up to 80% of carbon fire reinforced epoxy resins and the appropriate adhesives to facilitate fabrication. One might argue, therefore, that a modern Formula 1 chassis consists of a series of “plastic” mouldings held together with glue! Many of these structures are very highly stressed and required to operate in aggressive environments, particularly high temperatures. The consequences of failure of “Class A” structures can be catastrophic to the operation of the vehicle and impinge on the safety of the driver. Although increasingly better understood, the science and engineering of adhesives is very much in its infancy. Consequently, the design and operation of bonded components tends to be a constantly evolving, semi-quantitative process that combines fracture and finite element analysis with practical experience. In recent years BAR Honda have been very successful using and developing adhesive technology. The process of “total quality management” (TQM) encompasses the whole operation from R&D and design through materials procurement, component manufacture and condition monitoring to ensure successful exploitation up to the point of withdrawal from service.

Inkjettable conductive adhesive for use in microelectronics and microsystems technology

Ink jet is an accepted technology for dispensing small volumes of material (50–500 picolitres). Currently traditional metal-filled conductive adhesives cannot be processed by ink jetting (owing to their relatively high viscosity and the size of filler material particles). Smallest droplet size achievable by traditional dispensing techniques is in the range of 150 μm, yielding proportionally larger adhesive dots on the substrate. Electrically conductive inks are available on the market with metal particles (gold or silver) <20 nm suspended in a solvent at 30–50 wt%. After deposition, the solvent is eliminated and electrical conductivity is enabled by a high metal ratio in the residue. Some applications include a sintering step. These nano-filled inks do not offer an adhesive function. Work reported here presents materials with both functions, adhesive and conductive. This newly developed silver filled adhesive has been applied successfully by piezo-ink jet and opens a new dimension in electrically conductive adhesives technology. The present work demonstrates feasibility of an inkjettable, isotropically conductive adhesive in the form of a silver loaded resin with a two-step curing mechanism: In the first-step, the adhesive is dispensed (jetted) and precured leaving a ‘dry’ surface. The second step consists of assembly (wetting of the 2nd part) and final curing.

An evaluation of the elastic properties of an adhesive layer using the tensile-butt joint test: Procedures and error estimates

Simple analytical formulae have been reported in literature to extract basic elastic material properties of adhesives subjected to tensile load. This work investigates the errors connected with the evaluation of the tensile butt-joint test of adhesive technology based on these analytical formulae. The substrate deformation is incorporated due to a simple method based on Hooke's law for a uniaxial stress state. A parameter study for different combinations of adherend/adhesive materials has been performed to estimate the error for two different procedures, i.e. close to the adhesive layer and at the ends of the substrates, to measure the macroscopic strain. It is found that the application of extensometers close to the adhesive layer yields to an error of less than 0.2% if the substrate correction is incorporated.

Advanced adhesive technology

Advanced adhesive technology

溶接・接合をめぐる最近の動向 第ＩＩ部 産業界の最近の動向と溶接工学 Ｉ 材料技術 ３．新素材（高分子）（最新の接着剤と接着技術の動向）

溶接・接合をめぐる最近の動向 第ＩＩ部 産業界の最近の動向と溶接工学 Ｉ 材料技術 ３．新素材（高分子）（最新の接着剤と接着技術の動向）

高接着易剥離技術

高接着易剥離技術

On the Thick-Adherend Tensile Shear Test of Adhesive Technology—Limitations and Correction Methods

Abstract The thick-adherend lap shear test is numerically investigated. It is shown that the adhesive stiffness influences significantly the uniformity of the adhesive stress distribution and the substrate deformation. Both effects determine the validity of the evaluated shear modulus of the adhesive. Two methods for the substrate deformation correction, i.e., a simple method based on Hooke's law, and a method based on a finite element simulation of a reference specimen, are compared. The correction method based on the finite element method reveals not only better results for the substrate deformation correction in comparison with the simple method based on Hooke's law, but also incorporates the non-uniformity of the adhesive stress distribution for higher stiffness of the adhesive in a considerable way. The possible error of this test method on the determination of the adhesive shear modulus is generally quoted as a function of the stiffness ratio between the adhesive and the substrates.

Tissue adhesion technology by using vibration energy

Tissue adhesion technology by using vibration energy

A general Weibull model for reliability analysis under different failure Criteria-application on anisotropic conductive adhesive joining technology

In this paper, a generic four-parameter model has been developed and applied to the anisotropic conductive adhesive (ACA) flip-chip joining technology for electronics packaging applications. The model can also be used to predict any minimum failure cycles if the maximum acceptable failure criterion (in this case, a preset electrical resistance value) is set. The original reliability testing from which the test data was obtained was carried out on flip-chip anisotropically conductive adhesive joints on an FR-4 substrate. In the study, nine types of ACA and one nonconductive film (NCF) were used. In total, nearly 1000 single joints were subjected to reliability tests in terms of temperature cycling between -40/spl deg/C and 125/spl deg/C with a dwell time of 15 min and a ramp rate of 110/spl deg/C/min. The reliability was characterized by single contact resistance measured using the four-probe method during temperature cycling testing up to 3000 cycles. A single Weibull model is used for two failure definitions defined as larger than 50 m/spl Omega/ and larger than 100 m/spl Omega/ respectively using the in situ electrical resistance measurement technique. The failure criteria are incorporated into this Weibull model. This paper shows the flexibility and usefulness of Weibull distribution in this type of applications.

TO BEVEL OR NOT IN ANTERIOR COMPOSITES

Composites are widely used for the functional and esthetic restorations of anterior teeth. The placement of a cavosurface margin bevel on the enamel margins of anterior composite preparations traditionally has been recommended to enhance retention and for esthetic reasons, as bevels result in a gradual transition between the restoration and the tooth. However, advances in adhesive and composite technology, as well as careful composite selection and application techniques, have made it possible to place adequate anterior composites without a bevel. Elimination of bevels results in more conservative cavity preparations, a simpler technique, a reduced restored surface area, and the preservation of tooth structure when the restoration is replaced. This Critical Appraisal summarizes clinical reviews and laboratory publications related to the influence of cavity preparation and, more specifically, cavosurface bevels on the performance of anterior composite restorations.