Material extrusion systems are the most common types of additive manufacturing systems, also known as three-dimensional (3D) printers. This article focuses on the general 3D printing processes as can be demonstrated and manipulated in desktop printers. The discussion includes details of the components involved in material extrusion as well as the melt extrusion solidification (during cooling) process, the underlying mechanism of road bonding, and the factors affecting good part quality. The discussion also covers support material, postprocessing, and road-quality considerations and the addition of infill in melt extrusion to the hollow spaces inside an object to give it structural strength. Information is also provided on different materials and associated material properties that affect the rate the printer is able to advance and retract material, thereby affecting the quality and rate at which a part is printed. The final section provides information on the mechanism of viscous extrusion 3D printing.

This article reviews the main theoretical and practical aspects of sequence normally followed in digital image-acquisition, processing, analysis, and output for material characterization. It discusses the main methods of digital imaging, image processing, and analysis, as applied to microscopy of materials. The article describes the basic concepts of sampling and resolution and quantization of light microscopy, scanning electron microscopy, and transmission electron microscopy. It discusses the acquisition of a digital image that accurately represents the sample under observation and output of the image to a printer. The methods used to enhance the digital image and to extract quantitative information are also described. Different types of image segmentation, namely, adaptive segmentation and contour-based segmentation, are reviewed. The article also presents case studies on the application of image processing and analysis to materials characterization.

Vat polymerization is a form of three-dimensional (3D) printing. Historically, it is the oldest additive manufacturing technique, with the development of stereolithography apparatus (SLA) by Charles Hull in 1986. This article outlines the various forms of vat polymerization techniques used for biomedical applications. Due to the complex nature of this printing process, many key print parameters and material properties need to be considered to ensure a successful print. These influential parameters are addressed throughout the article to inform the reader of the considerations that should be taken when using the vat polymerization technique. The article provides information on vat polymerization printer setup, the photo-cross-linking mechanism, and considerations using vat polymerization. In addition, it outlines and discusses the advancements of vat polymerization in the biomedical industry.

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.

The application of three-dimensional printers can be revolutionary as a tool for the customization and personalization of pharmaceutical dosage forms. The areas of 3D printing applicable to pharmaceutical manufacturing can be segregated into three categories: extrusion technologies, powder-bed fusion, and stereolithography. Common extrusion-based technologies are fused deposition modeling and pressure-assisted microsyringe; powder-bed fusion is separated by binder jet and selective laser sintering. The synergies between pharmaceutical, or active pharmaceutical ingredient (API), and polymer printing are discussed in this article, with particular attention to how the incorporation of small-molecule APIs changes the material selection, design considerations, processing parameters, and challenges associated with each technology.

This article provides an overview of the adoption of additively manufactured materials in dentistry. It discusses the practical workflows of a three-dimensional printing technology, vat photopolymerization. Three subgroups of the vat photopolymerization process are laser beam or classic stereolithography apparatus (SLA), direct light processing, and liquid-crystal-display-masked SLA. The article covers two subgroups of 3D printing resins-based appliances, namely intraoral and extraoral appliances. Information on various types of dental appliances and the fabrication of in-office appliances is provided. The article also reviews fourth-dimension printing and discusses the applications of the personalized care model in medicine and dentistry.

Additive manufacturing (AM), or three-dimensional (3D) printing, is a class of manufacturing processes that create the desired geometries of an object, or an assembly of objects, layer by layer or volumetrically. AM has been used extensively for manufacturing medical devices, due to its versatility to satisfy the specific needs of an intended medical field for the product/device. This article provides a comprehensive review of AM in medical devices by the medical specialty panels of the Food and Drug Administration (FDA) Code of Federal Regulations, Parts 862 to 892, including anesthesiology, ear and nose, general hospital, ophthalmic, plastic surgery, radiology, cardiovascular, orthopedic, dental, neurology, gynecology, obstetrics, physical medicine, urology, toxicology, and pathology. It is classified under these panels, and critical reviews and future outlooks are provided. The application of AM to fabricate medical devices in each panel is reviewed; lastly, a comparison is provided to reveal relevant gaps in each medical field.

Additive manufacturing (AM) security is considered an integral part of several broader security fields, including supply chain security and critical infrastructure security. This article presents a general guide to the types of data and locations of data as they may exist in a typical AM-using organization. It discusses the following threat categories: technical data theft, sabotage, illegal part manufacturing, and data infiltration and exfiltration. The article also presents a detailed discussion on countermeasures against threat categories.

Bridging the gap between education and medical practice, centralized hospital-based 3D printing, or what is termed point-of-care (POC) manufacturing, has been rapidly growing in the United States as well as internationally. This article provides insights into the considerations and the current workflow of creating 3D-printed anatomical models at the POC. Case studies are introduced to show the complex range of anatomical models that can be produced while also exploring how patient care benefits. It describes the advanced form of communication in medicine. The advantages as well as pitfalls of using the patient-specific 3D-printed models at the POC are addressed, demonstrating the fundamental knowledge needed to create 3D-printed anatomical models through POC manufacturing.