Martins Ugonna Obi, Patrick Pradel, Matt Sinclair and Richard Bibb
The purpose of this paper is to understand how Design for Additive manufacturing Knowledge has been developing and its significance to both academia and industry.
Abstract
Purpose
The purpose of this paper is to understand how Design for Additive manufacturing Knowledge has been developing and its significance to both academia and industry.
Design/methodology/approach
In this paper, the authors use a bibliometric approach to analyse publications from January 2010 to December 2020 to explore the subject areas, publication outlets, most active authors, geographical distribution of scholarly outputs, collaboration and co-citations at both institutional and geographical levels and outcomes from keywords analysis.
Findings
The findings reveal that most knowledge has been developed in DfAM methods, rules and guidelines. This may suggest that designers are trying to learn new ways of harnessing the freedom offered by AM. Furthermore, more knowledge is needed to understand how to tackle the inherent limitations of AM processes. Moreover, DfAM knowledge has thus far been developed mostly by authors in a small number of institutional and geographical clusters, potentially limiting diverse perspectives and synergies from international collaboration which are essential for global knowledge development, for improvement of the quality of DfAM research and for its wider dissemination.
Originality/value
A concise structure of DfAM knowledge areas upon which the bibliometric analysis was conducted has been developed. Furthermore, areas where research is concentrated and those that require further knowledge development are revealed.
Details
Keywords
Richard Bibb, Dominic Eggbeer, Peter Evans, Alan Bocca and Adrian Sugar
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…
Abstract
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.
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Keywords
Richard Bibb, Dominic Eggbeer and Peter Evans
Maxillofacial prosthetics is faced with increasing patient numbers and cost constraints leading to the need to explore whether computer‐aided techniques can increase efficiency…
Abstract
Purpose
Maxillofacial prosthetics is faced with increasing patient numbers and cost constraints leading to the need to explore whether computer‐aided techniques can increase efficiency. This need is addressed through a four‐year research project that identified quality, economic, technological and clinical implications of the application of digital technologies in maxillofacial prosthetics. The purpose of this paper is to address the aspects of this research that related to the application of rapid prototyping (RP).
Design/methodology/approach
An action research approach is taken, utilising multiple case studies to evaluate the current capabilities of digital technologies in the preparation, design and manufacture of maxillofacial prostheses.
Findings
The research indicates where RP has demonstrated potential clinical application and where further technical developments are required. The paper provides a technical specification towards which RP manufacturers can direct developments that would meet the needs of maxillofacial prosthetists.
Originality/value
Whilst research studies have explored digital technologies in maxillofacial prosthetics, they have relied on individual studies applying a single RP technology to one particular aspect of a prosthesis. Consequently, conclusions on the wider implications have not been possible. This research explored the application of digital technologies to every aspect of the design and manufacture of a series of maxillofacial prostheses. Unlike previous research, the cases described here addressed the application of RP to the direct manufacture of substructures, retention components and texture. This research analyses prosthetic requirements to ascertain target technical specifications towards which RP processes should be developed.
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Keywords
Richard Bibb, Dominic Eggbeer and Robert Williams
The aim of this study was to explore the application of rapid manufacturing (RM) to the production of patient specific, custom‐fitting removable partial denture (RPD) alloy…
Abstract
Purpose
The aim of this study was to explore the application of rapid manufacturing (RM) to the production of patient specific, custom‐fitting removable partial denture (RPD) alloy frameworks. RPDs are metal frameworks designed to retain artificial replacement teeth in the oral cavity.
Design/methodology/approach
The study was undertaken by applied case study. An RPD was designed using computer‐aided design software according to well‐established dental technology design principles, based on a digitally scanned cast produced from an impression of the patient's mouth. The RPD design was then exported as an STL file in preparation for direct manufacture using selective laser melting. Dimensionally accurate frameworks were manufactured in 316L stainless steel and chromium‐cobalt alloy. These were assessed for accuracy of fit and function on the patient cast and on the patient in clinic.
Findings
This successful case study demonstrates that an RM approach can produce fully functional, precisely fitting RPD frameworks for specific individual patients.
Research limitations/implications
The study was based on a single design produced using two materials. Further studies are in progress to show that the results can be achieved on a regular and predictable basis.
Practical implications
This study provides some practical guidance for the application described and suggests that similar success may be achieved in related custom‐fitting applications.
Originality/value
The paper demonstrates the successful application of a novel approach to the design and manufacture of custom‐fitting dental devices.
Details
Keywords
Ana R. Lapcevic, Danimir P Jevremovic, Tatjana M Puskar, Robert J. Williams and Dominic Eggbeer
The purpose of this paper is to analyse structure and measure hardness of Co-Cr dental alloy samples made with two different technologies, conventional casting method (CCM…
Abstract
Purpose
The purpose of this paper is to analyse structure and measure hardness of Co-Cr dental alloy samples made with two different technologies, conventional casting method (CCM samples) and additive direct metal laser sintering technology (DMLS samples), and to compare the results.
Design/methodology/approach
CCM samples were made in a conventional casting machine, using remanium 800+ Co-Cr dental alloy (Dentaurum, Ispringen, Germany). DMLS samples were fabricated out of EOS CC SP2 Co-Cr alloy (EOS, GmbH, Munich, Germany) using DMLS technology. Samples for structural analysis were plate-shaped (10 × 10 × 1.5 mm3) and for the hardness test were prismatic-shaped (55 × 10.2 × 11.2 mm3). Structure was analysed via an inverting microscope and colour metallography method.
Findings
CCM samples have a dense, irregular dendritic mesh, which is typical for the metallic phase of the Co-Cr dental alloy. DMLS alloy has a more homogenous and more compact structure, compared to CCM. Metals, the alloy basis consists of, form semilunar stratified layers, which are characteristic for the additive manufacturing (AM) technique. Hardness values of DMLS (mean value was 439.84 HV10) were found to be higher than those of CCM (mean value was 373.76 HV10).
Originality/value
There are several reports about possible use of AM technologies for manufacturing dental devices, and investigation of mechanical properties and biocompatibility behaviour of AM-produced dental alloys. Microstructure of Co-Cr alloy made with DMLS technology has been introduced for the first time in the present paper.
Details
Keywords
Noor Abdullah Al Mortadi, Dominic Eggbeer, Jeffrey Lewis and Robert Williams
The purpose of this study is to develop and apply clinically relevant methods of analysing the accuracy of dental appliances fabricated using additive manufacture (AM) compared to…
Abstract
Purpose
The purpose of this study is to develop and apply clinically relevant methods of analysing the accuracy of dental appliances fabricated using additive manufacture (AM) compared to the computer-aided design (CAD) geometry. The study also compared fit between conventionally laboratory-fabricated and AM-produced base plates.
Design/methodology/approach
The techniques were applied to two types of dental devices where AM fabrication methods could foreseeably be used as an alternative to laboratory production. “L” and cubic shapes of defined dimensions and spatial locations were positioned on the devices which were fabricated using AM. For assessing the dimensions, the “L” and cubic shapes were then measured on the physical builds ten times and compared to the CAD model. To assess the fit of AM and lab-produced devices, three upper and three lower conventionally fabricated acrylic base plates were compared to three upper and three lower plates. Silicone impression material was allowed to set between the casts and the base plates which filled any discrepancy between the two surfaces. The thickness of this silicone media was measured ten times at five different points on each base plate type and the results compared.
Findings
The results indicated that the evaluated CAD/AM technique is able to produce dental appliance components that are consistent with tolerance levels that would be expected with conventional methods of baseplate design. This research demonstrated that a fully CAD/AM methodology represents a potentially viable alternative to conventional lab-based methods for two types of dental appliances.
Originality/value
This work is original. The authors do not believe any previous papers similar to the one submitted have been published.
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Esfandyar Kouhi, Syed Masood and Yos Morsi
Combination of advanced imaging, designing and manufacturing techniques has been rapidly developed in recent years for diagnostic and therapeutic purposes for medical devices. The…
Abstract
Purpose
Combination of advanced imaging, designing and manufacturing techniques has been rapidly developed in recent years for diagnostic and therapeutic purposes for medical devices. The purpose of this paper is to present a methodology for design and fabrication procedure of medical models using computer‐aided design (CAD) and fused deposition modeling (FDM) technique for application in the mandibular reconstructive surgery.
Design/methodology/approach
Case studies of patients with mandibular defects are examined using CAD model construction including data acquisition from computerized tomography scan and data processing. Furthermore, the effect of advanced manufacturing parameters settings in FDM methodology is investigated.
Findings
The models were used in assisting the surgeons in their reconstruction planning. A significant improvement regarding the success and convenience in surgery planning been reported.
Originality/value
This paper explores the application and viability of FDM rapid prototyping technology for fabrication of complex mandibular models used for reconstructive surgery.
Details
Keywords
Frank Alifui‐Segbaya, Paul Foley and R.J. Williams
Rapid manufacture‐produced cobalt chromium alloys are beginning to be used in dentistry but there are few published results relating to their properties. The purpose of this paper…
Abstract
Purpose
Rapid manufacture‐produced cobalt chromium alloys are beginning to be used in dentistry but there are few published results relating to their properties. The purpose of this paper is to determine the corrosion resistance of a rapid manufacture‐produced dental alloy and compare it to a standard dental casting alloy.
Design/methodology/approach
In accordance with ISO 22674, ten samples of each alloy were fabricated in approximately 45 mm×10 mm×2 mm rectangular prisms, a sample number in excess of the standard requirements. The groups were further divided into those with highly polished surfaces and those with electrobrightened surfaces. Each sample was immersed in artificial saliva, suspended by a nylon thread for 42 days at 37°C. Readings for cobalt, chromium and molybdenum ions released into solutions were obtained using an atomic absorption spectrometer at 1, 4, 7, 14, 21, 28, 35, and 42 day intervals at a detection limit of one part per million.
Findings
Ion release of cobalt, chromium and molybdenum was well within the threshold prescribed by the standard. The alloys were safe for use as dental devices with respect to the above metals. The rapid manufacture alloy however performed better. In addition the data indicated that for both alloys, there was no discernable difference between a polished and an electrobrightened surface.
Originality/value
The rapid manufacture alloy studied shows a safe level of corrosion resistance with respect to cobalt, chromium and molybdenum according to ISO definitions. Further biocompatibility tests are recommended.
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Keywords
Sadegh Rahmati, Farid Abbaszadeh and Farzam Farahmand
The purpose of this paper is to present an improved methodology for design of custom‐made hip prostheses, through integration of advanced image processing, computer aided design…
Abstract
Purpose
The purpose of this paper is to present an improved methodology for design of custom‐made hip prostheses, through integration of advanced image processing, computer aided design (CAD) and additive manufacturing (AM) technologies.
Design/methodology/approach
The proposed methodology for design of custom‐made hip prostheses is based on an independent design criterion for each of the intra‐medullary and extra‐medullary portions of the prosthesis. The intra‐medullar part of the prosthesis is designed using a more accurate and detailed description of the 3D geometry of the femoral intra‐medullary cavity, including the septum calcar ridge, so that an improved fill and fit performance is achieved. The extra‐medullary portion of the prosthesis is designed based on the anatomical features of the femoral neck, in order to restore the original biomechanical characteristics of the hip joint. The whole design procedure is implemented in a systematic framework to provide a fast, repeatable and non‐subjective response which can be further evaluated and modified in a preplanning simulation environment.
Findings
The efficacy of the proposed methodology for design of custom‐made hip prostheses was evaluated in a case study on a hip dysplasia patient. The cortical bone was distinguished from cancellous in CT images using a thresholding procedure. In particular the septum calcar ridge could be recognized and was incorporated in the design to improve the primary stability of the prosthesis. The lateral and frontal views of the prosthesis, with the patient's images at the background, indicated a close geometrical match with the cortical bone of femoral shaft, and a good compatibility with the anatomy of the proximal femur. Also examination of the cross sections of the prosthesis and the patient's intra‐medullary canal at five critical levels revealed close geometrical match in distal stem but less conformity in proximal areas due to preserving the septum calcar ridge. The detailed analysis of the fitting deviation between the prosthesis and point cloud data of the patient's femoral intra‐medullary canal, indicated a rest fitting deviation of 0.04 to 0.11 mm in stem. However, relatively large areas of interference fit of −0.04 mm were also found which are considered to be safe and not contributing to the formation of bone cracks. The geometrical analysis of the extra‐medullary portion of the prosthesis indicated an anteversion angle of 12.5 degrees and a neck‐shaft angle of 131, which are both in the acceptable range. Finally, a time and cost effective investment casting technique, based on AM technology, was used for fabrication of the prosthesis.
Originality/value
The proposed design methodology helps to improve the fixation stability of the custom made total hip prostheses and restore the original biomechanical characteristics of the joint. The fabrication procedure, based on AM technology, enables the production of the customized hip prosthesis more accurately, quickly and economically.
Details
Keywords
Yih‐Lin Cheng and Jin‐Chiou Chu
A continuous positive airway pressure (CPAP) device is one of the main treatments for obstructive sleep apnea (OSA) patients. Most patients treated by this method complain about…
Abstract
Purpose
A continuous positive airway pressure (CPAP) device is one of the main treatments for obstructive sleep apnea (OSA) patients. Most patients treated by this method complain about the comfortableness of the mask, but the commercial mask cushions are only available in fixed sizes. Therefore, the purpose of this paper is to apply the rapid tooling (RT) technique to manufacture customized nasal mask cushions, to increase the performance and with price competitiveness.
Design/methodology/approach
The patient's face was first duplicated twice by Hygrogum and plaster. The face model, on which the cushion CAD design was based, was digitized by the reverse‐engineering technology. The RT of the cushion was then designed and manufactured by two rapid prototyping techniques – Objet's PolyJet and shape deposition manufacturing (SDM). Finally, silicone was cast into the RT to obtain customized cushions. The customized cushion was compared with two other commercial cushions through fit testing and cost estimation.
Findings
The proposed approach can successfully manufacture customized cushions within a day. The SDM process has advantages in this application over Objet's system. The fit testing showed that the fit factor of the customized cushion was better and less loading was required, which should lead to great improvement in the patient's comfort. Moreover, the price‐to‐performance ratio of the customized cushion can be lower than the commercial ones if more than three cushions were made by a single rapid tool.
Originality/value
This paper has proposed a new application of RT on customized nasal mask cushions for CPAP devices. The customized cushion has lower price‐to‐performance ratio and the cost remains competitive.