The appropriate application of computer-aided design and manufacture techniques in silicone facial prosthetics

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Three-dimensional Computer Tomography (CT) data from a recent scan was used to obtain facial anatomy from a patient requiring an ocular prosthesis. The CT data was imported into the computer aided design (CAD) package, FreeForm® that was used to digitally design the prosthesis pattern using sculpting and shaping tools. The digital prosthesis pattern was then manufactured using a ThermoJet® rapid prototyping machine, printing in a wax material suitable for integration with traditional prosthesis Grafting techniques. Handcrafting and traditional laboratory techniques were then used to ensure the pattern fitted the patient and to integrate additional features before the mould was created. The final prosthesis was completed in silicone and successfully fitted to the patient with a pleasing aesthetic result.

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... As shown in Fig. 2, the first article to utilise AM for ocular and orbital prostheses was published in 2004 [9], demonstrating the AM of a wax pattern for moulding an orbital prosthesis. Six years passed before any further published research in 2010, with further AM moulding techniques trialled until the first end-use additively manufactured part was incorporated into a facial prosthesis in 2014 [10]. ...
... As shown in Fig. 4, the dominant use of AM in the literature was the creation of moulds (65%, n = 15). Often these were combined with the use of AM to create a prototype to test-fit on a patient or model [9,11,13,19,25,28,30], which could then double-up as a mould or be used to create an impression. Direct AM of end-use components was less common, trialled in 39% of articles (n = 9). ...
... End-use parts are not biocompatible and require coating with PMMA or used as a mould to cast with biocompatible silicone [12,20,21,24,29] Experience in computer-aided design (CAD) technology is required, which is not part of traditional skillset for prosthetist [10,13,15,21,25,30,31] AM times are slow (although they can also happen overnight or while a specialist does other things) [26,30] Rough surface quality of parts requires additional post-processing e.g. polishing [9,23] Challenges associated with using 3D scanners e.g. patient movement or scanning anatomy with hair [13,14,24] Expert manual skills are still required for some steps of the workflow [21,27] Use of CT scanning for the purposes of creating a prosthetic increases patient exposure to potentially harmful radiation [11,17] ...
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Orbital and ocular prosthesis fabrication is traditionally a manual process requiring highly skilled prosthetists practiced in a variety of manual manufacturing techniques and materials. However, as additive manufacturing and digital modelling technologies mature, many of these processes can be digitised. This systematic review aims to provide an overview of published literature, presenting the trends and common findings that can be used to inform the future research directions of the field. The method follows the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) 2015. PubMed, ProQuest, Scopus and Web of Science databases were searched for articles published between January 1984 and May 2021. Twenty-three articles met inclusion criteria, the first published in 2004. Over half of the articles were published since 2019. 3D scanning was the most common input for designing a prosthesis, used in 52% of articles (n = 12), followed by CT scans in 35% (n = 8). Fused deposition modelling (FDM) was the dominant additive technology, featured in 39% of articles (n = 9), followed by material jetting (MJ) in 26% of articles (n = 6). 65% of articles (n = 15) used additive manufacturing to create moulds or parts for impressions, while 39% (n = 9) used the printed outcomes in final prostheses. Additive manufacturing is increasingly being investigated for orbital and ocular prostheses; however, the field is dominated by one-off case studies and will require larger studies in order to provide clear evidence for the benefits and limitations reported in the literature.
... Examples of 3D printed pattern, shell, wax pattern, core and mould are shown in Fig. 2. (a) SLS made polyamide-based models of heat exchanger for a Pratt & Whitney PW6000 engine [13] (b) Resin shell + slurry filling for wax making die [26] (c) Patterns fabricated by direct and indirect RT routes for sand and investment casting [23] : R-resin, W-wax, PU-polyurethane, RTV-a rubber, S-solid, VCvacuum casting, WIM-wax injection moulding (d) Assembled core and mould fabricated by 3DP [35] 2.1 Rapid tooling-3D printing of prototype, pattern, core box and wax injection mould A number of direct routes using 3D printing methods such as FDM, LOM, SLA, SLS, etc., as well as indirect routes (3D printing methods coupled with secondary or soft-tooling processes like vacuum casting), are available for rapid fabrication of a prototype, pattern, core box, etc. for the first step in the casting process [8][9][10][11][12][13][14][15][16][17][18][19][20] . This is also called rapid tooling (RT). ...
... However, SLA parts age rapidly, resulting in warping and brittleness. Thermojet printing was used to print wax patterns for investment casting [19] . Thin layer thickness enables very smooth part surfaces, so it is suitable for small parts such as jewellery. ...
3D printing is such a magical technology that it extends into almost every sector relating to manufacturing, not to mention casting production. In this paper, the past, present and future of 3D printing in the foundry sector are profoundly reviewed. 3D printing has the potential to supplement or partially replace the casting method. Today, some castings can be directly printed by metal powders, for example, titanium alloys, nickel alloys and steel parts. Meanwhile, 3D printing has found an unique position in other casting aspects as well, such as printing the wax pattern, ceramic shell, sand core, sand mould, etc. Most importantly, 3D printing is not just a manufacturing method, it will also revolutionize the design of products, assemblies and parts, such as castings, patterns, cores, moulds and shells in casting production. The solid structure of castings and moulds will be redesigned in future into truss or spatially open and skeleton structures. This kind of revolution is just sprouting, but it will bring unimaginable impact on manufacturing including casting production. Nobody doubts the potential of 3D printing technologies in manufacturing, but they do have limitations and drawbacks.
... In recent years, handcrafted techniques have been used as a method of producing maxillofacial prostheses. This process, in addition to being long and costly, restricts the quality of the prosthesis to the manual skill of the prosthetist [9]. Aiming at the brevity and the reduction of the manual processes, new methodologies of auricular prosthesis production using additive manufacturing technology (AM) emerged. ...
... Developments in this area are moving towards exploiting advanced design and fabrication technologies to design and produce implants, patterns or templates that enable the fabrication of custom fitting prostheses without requiring a model of the anatomy to be made (Vander Sloten et al., 2000;Bibb et al., 2002;Eggbeer et al., 2004;Evans et al., 2004;Singare et al., 2005). However, there is also growing desire from clinicians to conduct more of the surgical planning using three-dimensional computer software. ...
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Purpose The computer‐aided design (CAD) and manufacture of custom‐fitting surgical guides have been shown to provide an accurate means of transferring computer‐aided planning to surgery. To date guides have been produced using fragile materials via rapid prototyping techniques such as stereolithography (SLA), which typically require metal reinforcement to prevent damage from drill bits. The purpose of this paper is to report case studies which explore the application of selective laser melting (SLM) to the direct manufacture of stainless steel surgical guides. The aim is to ascertain whether the potential benefits of enhanced rigidity, increased wear resistance (negating reinforcement) and easier sterilisation by autoclave can be realised in practice. Design/methodology/approach A series of clinical case studies are undertaken utilising medical scan data, CAD and SLM. The material used is 316L stainless steel, an alloy typically used in medical and devices and surgical instruments. All treatments are planned in parallel with existing techniques and all guides are test fitted and assessed on SLA models of the patients' anatomy prior to surgery. Findings This paper describes the successful application of SLM to the production of stainless steel surgical guides in four different maxillofacial surgery case studies. The cases reported address two types of procedure, the placement of osseointegrated implants for prosthetic retention and Le Fort 1 osteotomies using internal distraction osteogenesis. The cases reported here have demonstrated that SLM is a viable process for the manufacture of custom‐fitting surgical guides. Practical implications The cases have identified that the effective design of osteotomy guides requires further development and refinement. Originality/value This paper represents the first reported applications of SLM technology to the direct manufacture of stainless steel custom‐fitting surgical guides. Four successful exemplar cases are described including guides for osteotomy as well as drilling. Practical considerations are presented along with suggestions for further development.
Medical modelling and the principles of medical imaging, Computer Aided Design (CAD) and Rapid Prototyping (also known as Additive Manufacturing and 3D Printing) are important techniques relating to various disciplines - from biomaterials engineering to surgery. Building on the success of the first edition, Medical Modelling: The application of Advanced Design and Rapid Prototyping techniques in medicine provides readers with a revised edition of the original text, along with key information on innovative imaging techniques, Rapid Prototyping technologies and case studies. Following an overview of medical imaging for Rapid Prototyping, the book goes on to discuss working with medical scan data and techniques for Rapid Prototyping. In this second edition there is an extensive section of peer-reviewed case studies, describing the practical applications of advanced design technologies in surgical, prosthetic, orthotic, dental and research applications.
This paper is the first in a series that aims to identify the specification requirements for advanced digital technologies that may be used to design and fabricate complex, soft tissue facial prostheses. Following a review of previously reported techniques, appropriate and currently available technologies were selected and applied in a pilot study. This study uses a range of optical surface scanning, computerized tomography, computer-aided design, and rapid prototyping technologies to capture, design, and fabricate a bone-anchored auricular prosthesis, including the retentive components. The techniques are assessed in terms of their effectiveness, and the results are used to identify future research and specification requirements to direct developments. The case study identifies that while digital technologies may be used to design implant-retained facial prostheses, many limitations need to be addressed to make the techniques clinically viable. It also identifies the need to develop a more robust specification that covers areas such as resolution, accuracy, materials, and design, against which potential technologies may be assessed. There is a need to develop a specification against which potential technologies may be assessed for their suitability in soft tissue facial prosthetics. The specification will be developed using further experimental research studies.
Implant-retained auricular prostheses present a challenge with regard to the esthetic placement of the margins of the prosthesis. A technique for the impression and master cast fabrication to produce an implant-retained auricular prosthesis is described. This technique allows control of the esthetic margin, fabrication of a durable master cast with planned blockout, and inclusion of a replica of the retentive bar, which allows processing duplicate prostheses without returning the retentive bar to the mold.
When considering reconstructive surgery it is often difficult to ascertain the exact nature of affected internal anatomy. Although advances in Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) have enabled the generation of 3D reconstructions of internal anatomy, they are often only available as fixed 2D images. These may obscure important details or prove ambiguous depending upon the angle of view. Another problem is maintaining accuracy of reconstruction that may involve osteotomy, tissue grafts or implants. In such circumstances the ability to plan and rehearse complex procedures can prove invaluable, greatly improving surgical results whilst helping to eliminate potential errors and reducing theatre time. In this context 3D scan data can be treated as the equivalent of Computer Aided Design (CAD) data and can be applied to the production of accurate physical models. The approach undertaken by the DERC is based on close collaboration with surgical departments and enables the rapid and economic production of medical models based on CT/MRI data. This paper illustrates the transfer of product design technologies into a clinical context. Specifically, the use of 3D surface scanning and rapid prototyping technologies as an aid to post operative reconstruction is described. An evaluation of the application of product development tools within a clinical context is presented. The paper concludes with an assessment of likely future application in this area.
The capture of highly accurate data describing the complex surfaces of the human body may prove extremely useful in many medical situations. The data provide a method of measuring and recording changes to the surface of a patient's soft tissue. The data may be applied to computer-controlled manufacturing techniques, such as rapid prototyping (RP). This enables accurate physical replicas of the patient topography to be produced. Such models may be used as an aid in the design and manufacture of prostheses. This paper describes an investigation aimed at identifying problems that may be encountered when scanning patients and describes the application of the resulting data in the design and manufacture of facial prostheses. The results of the experiment are presented together with a discussion of the accuracy and potential advantages afforded by this approach.
This is the author’s version of a work that was accepted for publication in Journal of Oral and Maxillofacial Surgery. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at: