John Jansen

Electrosprayed calcium phosphate coatings for biomedical purposes

The suitability of the electrostatic spray deposition (ESD) technique was studied for biomedical purposes—i.e., deposition of calcium phosphate (CaP) coatings onto titanium substrates. Using ESD, which is a simple, inexpensive deposition method for inorganic and organic coatings, it was possible to obtain thin CaP layers with an extremely wide range of chemical and morphological characteristics. Various CaP phases and phase mixtures were deposited, and a broad diversity of coating morphologies was produced by varying deposition parameters related to the ESD-apparatus and/or the precursor solutions. Electrosprayed CaP coatings were shown to be biocompatible with soft tissue, and the osteoconductive nature of electrosprayed CaP coatings was also proven in vivo. Particular interest was given to a unique, reticular coating morphology consisting of a porous network of variable pore size. This specific coating morphology offers the possibility of varying the specific surface area of electrosprayed CaP coatings to a large extent. Consequently, the degradation rate of CaP coatings and the incorporation and subsequent release of biological agents (e.g., growth factors) can be influenced by chemical as well as physical coating properties using the ESD technique. In that way, control over the biological activity of drug-releasing CaP coatings can be improved significantly compared to conventional coating techniques, which lack this chemical and morphological variability.

Calcium Phosphate Bioceramics and Cements

Abstract Calcium phosphate bioceramics and cements are bone grafting materials that exhibit unique bioactive and osteoconductive properties that make them a viable alternative for bone regeneration from more traditional autograft and allograft techniques. More specifically, calcium phosphate cements stand out as a favorable material because they are biodegradable and have excellent handling properties (i.e., injectability, moldability, and cohesion). This gives them the added advantage of being employed in minimally invasive surgical techniques and the ability to be molded into irregularly shaped defect sites. Their ideal handling properties are attributed to their synthesis process, which involves mixing a powder and liquid phase to form a self-setting paste that eventually hardens inxa0vivo. Strategies to improve these cements mechanically have been employed to expand their clinical applicability to more load-bearing sites. This chapter encompasses the fundamental properties of these cements (i.e., setting reactions, setting times, injectability, cohesion, and mechanical performance) and outlines strategies to modify and improve these properties. Finally, the clinical relevance of these cements is discussed.

Modifications of Poly(Methyl Methacrylate) Cement for Application in Orthopedic Surgery

Even with the emerging of newly-developed bone substitutes, poly(methyl methacrylate) (PMMA) cement is still a widely-used bone replacing biomaterial in orthopedic surgery with a long history. However, aseptic loosening, infection of the prosthesis and thermal necrosis to surrounding tissue are the common complications of PMMA. Therefore, additives have been incorporated in PMMA cement to target those problems. This chapter summarizes different additives to improve the performance of the PMMA cement, i.e.: (1) bioceramic additives; (2) filler additives; (3) antibacterial additives; (4) porogens; (5) biological agents, and (6) mixed additives. To improve the biological and mechanical performance of PMMA cement, mixed additives aiming to fabricate multifunctional PMMA seem the most suitable choice. Although in vivo animal studies have been conducted, long-term and clinical studies are still needed to evaluate the modifications of multifunctional PMMA cement for matching a specific clinical application.

Bone Sectioning Using a Modified Inner Diamond Saw

The availability and application of medical implants has increased dramatically during the last two decades, and the broad variety of implants ranges from knee prostheses to heart valves, and from pacemakers to breast prostheses. With increased life expectancy, it is further believed that the application of implants will progressively increase. Implants are partially or totally placed into the body for prosthetic, therapeutic, diagnostic, cosmetic, or experimental purposes. Biomaterials play an important role in many of these implants. The required properties of a material used for an implant can be classified roughly under the categories of biocompatibility, implant construction, and biomechanics.11 Biocompatibility refers to the interfacial reactions between biomaterials and tissue. Implant construction involves the engineering of the implant as well as its mechanical properties, such as hardness and strength. Biomechanics is concerned with the mechanical-dynamic properties of an implant and surrounding tissues. This chapter focuses on the sectioning of biomaterials used for hard-tissue implantation.