Adhesives and Sealants

David Christopher Watts, B. D. Ratner (Editor), A. S. Hoffman (Editor), F. J. Schoen (Editor), J.E. Lemons (Editor)

    Research output: Chapter in Book/Report/Conference proceedingChapter

    Abstract

    In the context of biomaterials, adhesion science and technology assume high importance. It is useful to commence with the slightly wider concept of bonding. It is evident that many biomaterial devices are structured from multiple components, and these need to retain their mutual integrity during clinical service. In this context, the bonds in question may include metallic welds, although these would not be considered within the domain of adhesion, any more than screw attachments that have a role in some implants.The most challenging issue is the creation of a durable interfacial bond between a biomaterial and its host tissue. In addition to the function of bonding, per se, anadhesive biomaterial may be required to fulfil a space-filling role – replacing some or all of any lost natural tissue. In the former case, the function may be termedgrouting. This is, for example, the primary function of bone cements in orthopedics. A further ideal function of an adhesive is that of sealing; that is, the preventionof ingress of moisture, air, biological fluids, bacteria or other species through the adhesively bonded zone.Adhesive is a general term, and in specific contexts may be replaced by designations such as cement, glue, paste, fixative, and bonding agent. Some adhesives may be designed to exhibit further functions, such as antibacterialaction, delivery of drugs or beneficial ions, such as the antibacterial ion Ag+ or fluoride (F−). Fluoride is a component of dental preventative treatments which initiates the partial replacement of hydroxyapatite (HA) – the tooth enamel’s normal crystalline composition – with fluorapatite (a related crystal which incorporates F−).Fluorapatite is more resistant to decay than HA. Sometimes the converse of adhesion, namely abhesion, is necessary in clinical treatment. This “non-stick” feature is required with blood-compatible biomaterials,and is exhibited by non-fouling surfaces covered with polyethylene glycol (PEG).During the past half-century there has been a strong convergence of the ancient technologies of adhesives and the modern science of adhesion – based especiallyon advances in surface science and the understanding of molecular adhesive mechanisms. This progress has been stimulated by widespread industrial uses and biomedical applications of adhesives. The former have been driven by advances in polymer science, and the adoption of lightweight alloy and non-metallic composite materials in the aerospace and automobile industries. Nevertheless, the stringent biomedical requirements for adhesives have led to some specialized developments.The diverse biomedical contexts (host environments) of adhesives each require appropriate materials and techniques. Biological hosts differ principally as to whether they consist of hard or soft tissues. Connected with this are the timescales required for adhesive/bonding durability. These may vary from days, in the case of wound-closure adhesives, to decades of years, in the cases of bonecements and dental restorations. The aim of this chapter is to give a sound introduction to the physico-chemical and materials science aspects of adhesives and sealants, together with a description of current systems utilized ina range of surgical practice. It does not attempt a detailed study of the molecular biological interactions of adhesives.
    Original languageEnglish
    Title of host publicationBiomaterials Science
    PublisherElsevier BV
    Pages889-904
    Number of pages16
    Edition3rd
    ISBN (Print)9780123746269
    Publication statusPublished - 2013

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