This article focuses on the quenching properties of vegetable and animal oils, including toxicity and biodegradability of vegetable/animal oils. The article provides a detailed discussion on the oxidation of vegetable/animal oils. The addition of antioxidants to stabilize soybean and palm oils is discussed, and the article concludes that substantially better performance is required if vegetable oils are to be effective functional equivalents to petroleum oil formulations. This may be done by selecting different vegetable oil compositions with less unsaturation, by applying genetic modification of soybean seed oils, or by chemically modifying and stabilizing the vegetable oil structure.

Additive manufacturing, or three-dimensional printing technologies, for biomedical applications is rather different from other engineering components, particularly for biomedical implants that are intended to be used within the human body. This article contains two sections: "Design and Manufacturing Considerations of 3D-Printed, Commercially Pure Titanium and Titanium Alloy-Based Orthopedic Implants" and "Device Testing Considerations Following FDA Guidance" for additive-manufactured medical devices. These are further subdivided into five major focus areas: materials; design, printing, printing characteristics and parameters as well as postprinting validation; removal of the many manufacturing material residues and sterilization; physical, chemical, and mechanical assessments of the final devices; and biological considerations of all the final devices including biocompatibility.

Inkjet printing is extremely precise in terms of the ejected microdroplets (picoliter volume), contributing an unparalleled lateral resolution. Additionally, the benefits of high-speed deposition, contactless ink delivery, and the use of a range of ink materials endorse this technique as suitable for high-throughput 3D manufacturing. This article provides an overview of inkjet 3D printing (also referred to as 3D inkjetting). It then highlights the major components and accessories used in commercial and laboratory-based 3D inkjet printers. Next, the article describes the process physics of the transient phenomena involved in both binder-jetting- and direct-inkjetting-based 3D printing. It then discusses the scope and advantages of 3D inkjetting in the manufacturing of metallic, ceramic, and polymer-based biomaterials. The article also discusses several approaches and methodologies to examine the in vitro cytocompatibility and in vivo biocompatibility of both binder-jetted and direct-inkjetted scaffolds for biomedical applications. Finally, it discusses the challenges and troubleshooting methodologies in 3D inkjetting of biomaterials.

One of the most frequently cited advantages of ceramics in dentistry relates to aesthetics, and the same applies for dental implants. Zirconia has emerged as the material of choice for nonmetal implants. This article introduces the reader to zirconia as an implant material, its properties, manufacturing processes, and the particular surface modifications and treatments that have rendered its surfaces biologically compatible with peri-implant soft and hard tissues.

This article focuses on friction and wear of automotive and aircraft brakes. It provides a comparison of friction and wear behaviors, frictional characteristics, and frictional performance of the friction materials. The article describes the components of brake friction materials and the classifications of brake lining materials. It discusses the effect of formulation compositions and manufacturing processes and the effect of braking operation conditions. The article provides information on aircraft brake linings, which operate under a wide range of kinetic energy conditions. The morphology effect of graphite on automotive brake drum and disk is explained. The article also describes the characteristics of specific wear rates for both normal and local cast iron in automotive brake drums and disk rotors. It provides information on noises, vibrations, and harshness caused by brake pads. The article concludes with information on physical and chemical testing of brakes and toxicity of brake formulation and regulations.

This article describes the nitriding methods of titanium alloys such as plasma nitriding and gas nitriding. It focuses on the interaction of titanium alloys, interaction of titanium with nitrogen, and the interaction of titanium with oxygen, carbon, and hydrogen. The article provides information on the wear and fatigue properties and corrosion resistance of nitrided titanium alloys, as well as the effect of nitriding on the biocompatibility of titanium. It also compares plasma-nitrided titanium alloys with alloy steels. It concludes with a short discussion on the effect of nitriding on the surface properties of titanium and two-phase α + β alloys.

This article discusses the mechanisms of metal and alloy biocompatibility. It provides information on early testing and experience with metals in medical device applications. The article describes the response of implant and particulate materials to severe corrosion. It provides a description of metal binding and its effects on metabolic processes. Hypersensitive responses to metal ions are also reviewed. The article concludes with a discussion on the possible cancer-causing effects of metallic biomaterials.

This article provides an overview of curing techniques, adhesive chemistries, surface preparation, adhesive selection, and medical applications of adhesives. The curing techniques are classified into moisture, irradiation, heat, and anaerobic. The article highlights the common types of curable adhesives used for medical device assemblies, including acrylics, cyanoacrylates, epoxies, urethanes, and silicones. Other forms of adhesives, such as hot melts, bioadhesives, and pressure-sensitive adhesives, are also discussed. The typical characteristics and applications of biocompatible medical device adhesives are listed in a table. The article concludes with a section on the selection of materials for medical adhesives.

Ceramics are used widely in a number of different clinical applications in the human body. This article provides a brief history of the bioceramics field and discusses the classification of bioceramics. These include bioinert ceramics, bioactive ceramics, and bioresorbable ceramics. The article describes third-generation bioceramics, classified by Hench and Polak, such as silicate-substituted hydroxyapatite and bone morphogenic protein-carrying calcium phosphate coatings. It reviews several examination methods used to test the biocompatibility of ceramics, namely, biosafety testing, biofunctionality testing, bioactivity testing, and bioresorbability testing.

This article describes the corrosion resistance and ion release from main transition metallic bearings used as medical devices. It discusses the main issues associated with the in vivo presence of ions and their biocompatibility during the exposure of patients to different aspects of ion toxicity. These include ion concentration and accumulation in organisms, reactive oxygen species and oxidative stress, and carcinogenicity stimulated by the corrosion process and toxic ions release.

This article discusses the composition of the major components of dental composite resins: organic resin matrix, filler, coupling agents, and initiator-accelerator systems. It describes the properties of composite resins that are related to the amount and type of filler and resin-matrix compositions. The article also discusses the compositions, properties, and clinical applications of polyacid-modified composite resins and resin-modified glass-ionomer cements. It concludes with information on biodegradation and biocompatibility of resin-based restorative materials.

This article focuses on ceramics, glasses, glass-ceramics, and their derivatives, that is, inorganic-organic hybrids, in the forms of solid or porous bodies, oxide layers/coatings, and particles with sizes ranging from nanometers to micrometers, or even millimetres. These include inert crystalline ceramics, porous ceramics, calcium phosphate ceramics, and bioactive glasses. The article discusses the compositions of ceramics and carbon-base implant materials, and examines their differences in processing and structure. It describes the chemical and microstructural basis for their differences in physical properties, and relates the properties and hard-tissue response to particular clinical applications. The article also provides information on the glass or glass-ceramic particles used in cancer treatments.

This article outlines the selection criteria for choosing an implant material for biomedical devices in orthopedic, dental, soft-tissue, and cardiovascular applications. It details the development of various implants, such as metallic, ceramic, and polymeric implants. The article discusses specific problems associated with implant manufacturing processes and the consequent compromises in the properties of functionally graded implants. It describes the manufacturing of the functionally-graded hip implant by using the LENS process. The article reviews four different types of tissue responses to the biomaterial. It discusses the testing methods of implant failure, such as in vitro and in vivo assessment of tissue compatibility.

This article focuses on the specific aspects of nitinol that are of interest to medical device designers. It describes the physical metallurgy, physical properties, and tensile properties of the nitinol. The article discusses the factors influencing superelastic shape memory effects, fatigue, and corrosion in medical device design. It reviews the biocompatibility of nitinol based on corrosion behavior. The article explains the general principles, potential pitfalls, and key properties for manufacturing, heat treatment, and processing of nitinol.

Implant debris is known to cause local inflammation, local osteolysis, and, in some cases, local and systemic hypersensitivity. The debris can be stainless steel, cobalt alloy, and titanium alloy, and soluble debris obtained due to wear from all orthopedic implants. This article addresses the biologic aspects of implant debris, both locally and systemically. It describes debris-induced local effects, particle-induced proinflammatory responses, and debris-induced systemic effects. The article concludes with a discussion on the four systemic effects of implant debris, namely, neuropathic effects, hypersensitivity effects, carcinogenicity, and general toxicity.

This article provides a summary of the biocompatibility or biological response of metals, ceramics, and polymers used in medical implants, along with their clinical issues. The polymers include ultrahigh-molecular-weight polyethylene, nonresorbable polymer, and resorbable polymers.

This article discusses several aspects of biocompatibility of polymers, including the selection of a suitable polymer, specific use of a material, contact of polymer on body site, and duration of the contact. It describes the factors influencing the biological response of the polymer from a biocompatibility perspective. These include raw materials, the manufacturing process, cleaning and sterilization processes, and biodegradation and biostability. The article reviews the general testing methods of polymers, such as chemical, mechanical and thermal. It concludes with a section on the guidance, provided by the regulatory authorities, on the biocompatibility testing of polymers and polymer-containing devices that can aid in selecting the right analysis.

Titanium and its alloys have been used extensively in a wide variety of implant applications, such as artificial heart pumps, pacemaker cases, heart valve parts, and load-bearing bone or hip joint replacements or bone splints. This article discusses the properties of titanium and its alloys and presents a list of titanium-base biomaterials. Titanium components are produced in wrought, cast, and powder metallurgy (PM) form. The article describes forging, casting, and heat treating of titanium alloys for producing titanium components. Typical mechanical properties of titanium biomedical implant alloys are listed in a tabular form. The article presents an overview of the surface-modification methods for titanium and its alloys implants. It concludes with a section on biocompatibility and in vivo corrosion of titanium alloys.

The biocompatibility of a material relates to its immunological response, toxicity profile, and ability to integrate with surrounding tissue without undesirable local or systemic effects on a patient. This article underscores the transformation of the medical device design ecosystem engaged as an integral part of the device ecosystem. It discusses the applications of biomaterials, including orthopedic, cardiovascular, ophthalmic, and dental applications. The article describes four major categories of biomaterials such as metals, polymers, glass and ceramics, and composites. A discussion on natural materials, nanomaterials, and stem cells is also provided. The article concludes with examples of biomaterials applications, such as endovascular devices, knee implants, and neurostimulation.