Past, Present, and Future of Soft‐Tissue Prosthetics: Advanced Polymers and Advanced Manufacturing

Abstract

past 30 years, [12,13] it is only the last decade that has seen its rapid development as part of the fourth industrial revolution. [14] This change in practice is evidenced by the significant fraction of recent literature describing advances in 3D printed prostheses, including technological advances [4,15-18] and clinical reports. [19,20] Further innovations involving collaborations between clinicians, academics, and industry, promise even greater capabilities. The future will see 3D printers that can mix materials as desired during fabrication [21] and those that can 3D print organic semiconductors and piezoelectric polymers for sensing and bionics [22-24] (Figure 1). This report is focused on polymers for soft tissue, external, personalized, prosthetics with clinical applications for the ear, [25] nose, [26] eye, [27] face, [28] breast, [29] and hand. [30] The characteristics of both traditional and 3D printable polymeric materials, as well as current advanced manufacturing technologies and those in development, are also reviewed. The earliest evidence of prosthetics dates back to ≈2300 BC, where Egyptian mummies have been discovered with eye, nose, and genital reconstructions fashioned from plaster packed with mud, sand, linen, butter, or soda (Figure 1). [31] Wood, cloth, natural waxes, resins, and metals were later used as the material of choice for rudimentary prostheses. [32] Prostheses remained relatively unchanged for thousands of years until the 16th century, where prosthetic noses and eyes were made from parchment, wax, wood, hard rubber, gold, silver, and copper. [33] Metals continued as a fundamental material throughout the 19th century, largely due to their ability to be shaped and molded as needed. [34,35] One of the first polymers to be used in prosthetics, poly(methyl methacrylate) (PMMA), was developed in response to the glass shortages in the World Wars of the 20th Century. [36] This polymer went on to become the most common prosthetic material of the time, and still finds use today in artificial eyes [33] and prosthetic substructures. [37] Further innovations in the 20th century produced many new polymers, such as vinyls, copolymers, plastisols, and one of the most significant materials in prosthetics, silicone. [38] Discovered in the early 1900s by Fredrick Kipping, silicone was first used in prosthetics by George W Barnhart in 1960. [39] This versatile polymer remains a primary prosthetic material today due to its soft tissue-like properties, ease of manipulation, chemical inertness, durability, and excellent biocompatibility. [40,41] The search for alternative materials Millions of people worldwide experience disfigurement due to cancers, congenital defects, or trauma, leading to significant psychological, social, and economic disadvantage. Prosthetics aim to reduce their suffering by restoring aesthetics and function using synthetic materials that mimic the characteristics of native tissue. In the 1900s, natural materials used for thousands of years in prosthetics were replaced by syntheti...

Polymer 3D Printing Review: Materials, Process, and Design Strategies for Medical Applications

“…The wearable hand is low cost and provides a broad range of motion for users. Stretchable prosthetics with embedded actuators, signal processors, and sensors have also been tailored for individuals [ 109 , 110 ]. For instance, a smart wearable therapeutic device was fabricated with an embedded temperature sensor and programmable heater for self-activation according to a patient’s body temperature [ 111 ].…”

Are Nano TiO2 Inclusions Improving Biocompatibility of Photocurable Polydimethylsiloxane for Maxillofacial Prosthesis Manufacturing?

“…For extraoral prosthesis, the material used needs to mimic soft-tissue characteristics in terms of visual and tactile properties, being simultaneously physically and chemically stable, as well as having microbiological resistance and biocompatibility [3].…”

“…Maxillofacial prosthesis has different characteristics, depending on the type of defect needing to be restored (missing soft or hard tissue), requiring different types of materials. For extraoral prosthesis, the material used needs to mimic soft-tissue characteristics in terms of visual and tactile properties, being simultaneously physically and chemically stable, as well as having microbiological resistance and biocompatibility [3].…”

“…Consequently, the dynamic flexibility of the PDMS chains increase significantly, offering pliability and softness similar to human skin. As maxillofacial prosthesis are not worn while sleeping, removal and attachment must be straightforward [2], therefore mechanical properties, such as tensile strength, tear strength, and elongation at break are important, mainly around the thin edges of the prosthetic where adhesive need to be used for bonding with the skin [3]. Regarding this aspect, PDMS has some significant disadvantages as the low mechanical properties [6].…”

Studies on the Mechanical Parameters of Denture Base Acrylic Resins

“…Complete edentulous therapy continues to concern specialists everywhere, being considered as a domain of particular difficulty, because it is not limited to the design and fabrication of a full denture, because it addresses to one of the most complex pathology, generating imbalances of all the elements of the dento-maxillary system [1]. The installation of a full edentation should be seen as the beginning of an involution process of disturbing the physiological balance, generated by the constant depreciation of the anatomical structures of the whole body, with implications on the stomatognathic system, which can trigger permanent stresses, that places the elderly, in a state of psycho-somatic lability [2,3].…”