Additive manufacturing

Aim: To design a surgical template to guide the insertion of craniofacial implants for nasal prosthesis retention. Materials and methods: The planning of the implant position was obtained using software for virtual surgery; the positions were transferred to a free-form computer-aided design modeling software and used to design the surgical guides. A rapid prototyping system was used to 3D-print a three-part template: a helmet to support the others, a starting guide to mark the skin before flap elevation, and a surgical guide for bone drilling. An accuracy evaluation between the planned and the placed final position of each implant was carried out by measuring the inclination of the axis of the implant (angular deviation) and the position of the apex of the implant (deviation at apex). Results: The implant in the glabella differed in angulation by 7.78°, while the two implants in the premaxilla differed by 1.86 and 4.55°, respectively. The deviation values at the apex of the implants with respect to the planned position were 1.17mm for the implant in the glabella and 2.81 and 3.39mm, respectively, for those implanted in the maxilla. Conclusions: The protocol presented in this article may represent a viable way to position craniofacial implants for supporting nasal prostheses. © 2010 John Wiley & Sons A/S.

Keywords: CAD-CAM , Craniofacial implants , Nasal prosthesis , Rapid prototyping , Virtual surgery

In this paper, the complete procedure to design and construct reusable moulds for implant-based ear prosthesis and manufacture substructures by means of a computer aided design-computer aided manufacturing (CAD-CAM) procedure and rapid prototyping (RP) technology is presented. The scan of the healthy ear, the virtual superimposition of its mirrored image on to the defective side, and the rapid manufacturing of the substructure and of the mould eliminate several steps of traditional procedures (wax, stone, try-in). Moreover, the precise design and customization of the substructure is presented, with the original and engineered shape for the retention of the silicone. The time and cost saving results of this protocol are presented together with a discussion of the main design features that make the prosthesis a stable and reproducible system to improve rehabilitation of patients with auricular defects or absence.

Keywords: CAD/CAM , facial rehabilitation , prosthetic rehabilitation , rapid prototyping , reverse engineering

A basic approach toward the design of three-dimensional (3D) rapid prototyped magnetic scaffolds for hard-tissue regeneration has been proposed. In particular, 3D scaffolds consisting of a poly(ε-caprolactone) (PCL) matrix and iron oxide (Fe 3O 4) or iron-doped hydroxyapatite (FeHA) nanoparticles were fabricated through a 3D fibre deposition technique. As a first approach, a polymer to nanoparticle weight ratio of 90/10 (wt/wt) was used. The effect of the inclusion of both kinds of nanoparticles on the mechanical, magnetic, and biological performances of the scaffolds was studied. The inclusion of Fe 3O 4 and FeHA nanoparticles generally improves the modulus and the yield stress of the fibres if compared to those of neat PCL, as well as the modulus of the scaffolds. Micro-computed tomography has confirmed the possibility to design morphologically-controlled structures with a fully interconnected pore network. Magnetisation analyses performed at 378C have highlighted M-H curves that are not hysteretic; values of saturation magnetisation (M s) of about 3.9 emu/g and 0.2 emu/g have been evaluated for PCL/Fe 3O 4 and PCL/FeHA scaffolds, respectively. Furthermore, results from confocal laser scanning microscopy (CLSM) carried out on cell-scaffold constructs have evidenced that human mesenchymal stem cells (hMSCs) better adhered and were well spread on the PCL/Fe 3O 4 and PCL/FeHA nanocomposite scaffolds in comparison with the PCL structures. © 2011 Taylor & Francis.

Keywords: Biological and mechanical analyses , Hard tissue regeneration , Magnetic scaffold , Nanocomposite , Rapid prototyping

The production methodology of 3D constructs for tissue regeneration is usually a complex discontinuous process involving three different stages: (1) production of 3D matrices; (2) matrix sterilisation and cell seeding; (3) in vitro dynamic cell culture. This paper presents a novel automated bench-top manufacturing system called BioCell Printing, designed for the integrated, continuous and fully automated production and in vitro dynamic culture of tissue engineering constructs. The BioCell aims at the rapid production of tissue-engineered substitutes with low risk of contamination, increasing the chances of direct clinical application. © 2011 CIRP.

Keywords: Biomedical , Extrusion , Rapid prototyping

Accurately measuring an artefact of historical significance generally results in being able to extract information which is useful for evaluating what remains of the materials from a distant time. This allows scholars arrive at an exhaustive historical reading of the same artefact. Compared to the traditional measuring techniques, which can often be imprecise and complicated, 3D laser scanners measure the morphological characteristics of an artefact with extreme accuracy. Despite this, it is not always possible to choose the most appropriate sensors due to the geometric peculiarities, or indeed, the size of the object. The present work deals with two non-destructive analyses of an ancient stone sculpture, which for its morphology and size was scarcely compatible with the technical characteristics of either of the scanners used. Both scanners operate on the same technical principal, but are quite different from each other in terms of scale and precision. For these reasons, a complex 3D model (extremely appropriate given the original artefact) was draw out through a synergy of the two techniques. The virtual particularities of the model allowed it to be manipulated with the appropriate software. In fact, on the basis of qualitative parameters devised by researchers, it proved possible to reproduce the artefact's geometric form, both virtually and in the form of physical models, obtained through non-conventional restoration methods (R.P. techniques).It has also been possible to verify the state of degradation of the surface of the stone caused by the traditional methods of applying cataloguing or storage information to it.Finally, the results achieved provide opportunities for further research on certain geometrical characteristics of the stone which, as highlighted by the elaboration on the virtual model, seem to be traceable to non-manual, perhaps mechanical, processes. Therefore, the historical considerations which derive from this fact call certain scholars into play. © 2011 Elsevier Ltd.

Keywords: Arteafct , Rapid prototyping , Reconstructing , Scanner , Sculpture

Web-based e-commerce of rapid prototyping services is going to be a widely diffused methodology used to compete in a global market. A competitive market imposes a very accurate estimation of prototyping price. Prototype costs depend on many factors, some of which may be easily deduced, while some others consist in a complex function of the geometric model properties and of the specific technology employed to build a physical model. Build time, which affects some components of the prototype's build cost, is a critical factor to deduce. Build time depends not only on the prototype dimensions but also on the complexity of the shape that, in turn, affects the movement of the tool to form the object. A parametric approach to build cost estimation, suited for web-based e-commerce, is presented in this paper. Significant cost driving factors of layer manufactured objects are identified and instruments to evaluate them are proposed. Special attention has been paid to define a parametric approach to build time estimation. The proposed parametric approach analyses the geometrical features, which typically affect the build time of the main layer manufacturing technologies. The method is verified in some test cases related to FDM technology. © 2010 Taylor & Francis.

Keywords: Cost estimating , E-commerce , Rapid prototyping

This paper presents a new 3D design paradigmfor the development of specific custom-fit products, such as the soft socket of prostheses for lower limb amputees. It is centered on the digitalmodel of the human body and, contrarily to the traditional process almost manually based, it considers the integration of methods and tools coming from different research and application fields: Reverse Engineering, Medical Imaging, Virtual Prototyping, Physics-based Simulation, and Rapid Prototyping. The paper describes the techniques adopted to acquire and create the digital model of the residual limb, the procedure to generate the socket model, the strategy developed for the functional simulation of the socket-stump interaction and, finally, the realization of the physical prototype. Each design step is described with the related problems and the obtained results. Both trans-tibial and trans-femoral amputees have been considered; however, for now the complete process has been validated for trans-tibial prostheses. Major outcomes of the proposed approach stand in a better quality of the final product, in a shorter involvement of the amputee implying a lower psychological impact, in a limited use of physical prototypes, and in a shorter development time. Moreover, the resulting paradigm answers to the Collaborative Engineering guidelines by optimizing the interaction between different domains and enhancing their contributions in a homogeneous development framework. © 2010 Elsevier B.V. All rights reserved.

Keywords: Custom-fit products , Human-centric soft product design , Physics-based modeling for soft products , Prosthesis development process

The paper describes the development of a seating buck system for ergonomic evaluation of the driver's cab. Seating buck is a configurable structure that, thanks to the mixed reality technologies, allows us to simulate different driving seat and to perform different evaluation tests. In particular we are interested to evaluate the ergonomics of car's dashboard with its knobs, buttons, display and other control systems. For this reason, we studied and developed a seating buck system that addresses these issues. In particular, we investigated on the possibility of changing in real time the position of some components of the car dashboard with the aim of analysing different layouts. The effectiveness of the system has been subsequently validated through some test sessions with users. © Organizing Committee of TMCE 2010 Symposium.

Keywords: Ergonomic analysis , Haptic devices , Mixed reality , Rapid prototyping , Seating buck

Ear defects in patients affected by Treacher Collins syndrome necessitate the replacement of the existing anatomic residuals of the ears with custom-made prostheses. This paper describes a multidisciplinary protocol involving both medicine and computer-aided design/computer-aided manufacturing for manufacturing ear prostheses. Using innovative prototyping technologies together with conventional silicone processing procedures, a step-by-step procedure is presented. The complete workflow includes laser scanning of the defective regions of a patient's face, the use of 3D anatomic models from an ear digital library and rapid prototyping of both substructures for bar anchoring and moulds for silicone processing. © 2010 Taylor & Francis.

Keywords: Computer-aided design , Ear prostheses , Maxillofacial rehabilitation , Rapid prototyping , Reverse engineering , Treacher Collins syndrome

Restoration of a nasal defect after ablative surgery for squamous cell carcinoma necessitates replacing the missing volume and anchoring a prosthesis to the patient's face. This report describes the failure of plastic reconstructive surgery after ablation of a squamous cell cancer of the nose and the esthetic and functional restoration of the patient with a nasal prosthesis. The process of making an implant-supported prosthesis using digital technology, including digitized anatomic models from a "nose library," and the rapid prototyping of the mesiostructure for bar anchorage and of the mold for silicone processing are presented. © 2010 by Quintessence Publishing Co Inc.

Keywords: Computer-aided design , Computer-assisted manufacture , Maxillofacial prosthesis , Nasal prosthesis , Rapid prototyping

Most of robotic soft pads studied so far were made with a thick layer of homogeneous material shaped around a rigid core; their behavior has been widely investigated in the literature, mainly under compressive contact load, showing typical non-linear relationship between contact deformation and applied load (the so called power law). This paper proposes differentiated layer design, that is the adoption of a single elastic material, dividing the overall thickness of the pad into layers with different structural design (e.g. a continuous skin layer coupled with an internal layer with voids). The purpose is to modify the actual pad compliance and the resulting power law; in particular, given the material and the allowable pad thickness, to increase the compliance with respect to a non structured pad. Some possible internal layer structures are described, compatible with rapid prototyping manufacturing. Their compressive behaviors are tested and comparatively evaluated showing that the concept can work and be exploited for useful application.© 2009 IEEE.

Keywords: Experimental analysis , Fingertip design , Robotic hands , Soft fingers

This paper describes the multi-disciplinary approach to reconstruct the face of Dante Alighieri (1265-1321). Since Dante's sepulchre will be opened in 2021, the reconstructive process is based on morphological and metric data collected on the poet's cranium during the formal identification of his remains in 1921 by the anthropologist Fabio Frassetto, as well as on the resulting plaster model. Starting from this plaster model and a morphologically compatible reference mandible, since the original mandible was never found, a 3D digital model of the complete skull was obtained by reverse engineering and virtual modelling techniques. The most important aspect in this work was the method of virtual modelling proposed for the ex novo generation of the mandible. The physical model of the skull (cranium + mandible) was then produced by means of a rapid prototyping system. This model was finally used to recreate Dante's face via traditional facial reconstruction techniques currently used in forensic anthropology. © 2008 Elsevier Ltd. All rights reserved.

Keywords: 3D digital models , Facial reconstruction , Rapid prototyping , Reverse engineering

We developed a model to test new bone constructs to replace spare skeletal segments originating from new generation scaffolds for bone marrow-derived mesenchymal stem cells. Using computed tomography (CT) data, scaffolds were defined using computer-aided design/computer-aided manufacturing (CAD/CAM) for rapid prototyping by three-dimensional (3D) printing. A bone defect was created in pig mandible ramus by condyle resection for CT and CAD/CAM elaboration of bone volume for cutting and scaffold restoration. The protocol produced a perfect-fitting bone substitute model for rapid prototyped hydroxyapatite (HA) scaffolds. A surgical guide system was developed to accurately reproduce virtually planned bone sectioning procedures in animal models to obtain a perfect fit during surgery. © 2008 Elsevier Ltd. All rights reserved.

Keywords: Bone regeneration , CAD-CAM , Maxillofacial prosthesis , Rapid prototyping , Scaffold

Repairing critical human skull injuries requires the production and use of customized cranial implants and involves the integration of computer aided design and manufacturing (CAD and CAM). The main causes for large cranial defects are trauma, cranial tumors, infected craniotomy bone flaps and external neurosurgical decompression. The success of reconstructive cranial surgery depends upon: the preoperative evaluation of the defect, the design and manufacturing of the implant, and the skill of the operating surgeon. Cranial implant design is usually carried out manually using CAD although this process is very time-consuming and the quality of the end product depends wholly upon the skill of the operator. This paper presents an alternative automated method for the design of custom-made cranial plates in a PHANToM®-based haptic environment, and their direct fabrication in biocompatible metal using electron beam melting (EBM) technology. © 2008 Elsevier Ltd. All rights reserved.

Keywords: Custom cranial implant , Electron beam melting (EBM) , Haptic environment , PHANToM-based tools

Tissue engineering represents an interesting approach which aims to create tissues and organs de novo. In designing scaffolds for tissue engineering applications, the principal goal is to mimic the function of the natural extracellular matrix, providing a temporary template for the growth of target tissues. For this reason, scaffolds should possess suitable mechanical properties and architecture to play their specific role. In this paper, limitations of conventional scaffold fabrication methods will be briefly introduced, and rapid prototyping techniques will be described as advanced processing methods to realize customized scaffolds with controlled internal microarchitecture. Among the rapid prototyping techniques, the potential and challenges of 3D fiber deposition to create multifunctional and tailor-made scaffolds will be reviewed. © Società Italiana Biomateriali.

Keywords: 3D fiber deposition , Bioplotter , Rapid prototyping , Scaffolds , Tissue engineering

Applications are presented of the general shadow-projection moiré model described in the companion paper, "A general model for moiré contouring, part 1: theory." Two examples are discussed in detail. One example deals with the deflection of a large-size thin panel subjected to bending. The other example analyzes the accuracy that can be achieved in laser lithography rapid prototyping. The first example illustrates some theoretical aspects of the general contouring model proposed in this research and explains the reasons for differences between theoretical predictions and experimental results. In the second example, the whole process of data gathering and merging using geometric primitives and optimization techniques is demonstrated practically. Finally, a clear relationship between the measured standard deviations and moiré sensitivity values is obtained. The results show that the proposed methodologies lead to a quasi-quadratic correlation. © 2008 Society of Photo-Optical Instrumentation Engineers.

Keywords: contouring of surfaces , geometrical primitives , measurement of deflections , merging of different views , rapid prototyping , shadow/projection moiré

Purpose - The purpose of this paper is to describe the method of virtually and physically reconstructing the missing part of a badly damaged medieval skull by means of reverse engineering, computer-aided design (CAD) and rapid prototyping (RP) techniques. Design/methodology/approach - Laser scanning data were used to create the 3D model of the damaged skull. Starting from this digital model, a virtual reconstruction of the missing part of the skull, based on the ideal symmetry with respect to the mid-sagittal plane, was achieved in a CAD environment. Finally, the custom-designed model was directly fabricated by means of the RP process. Findings - The result shows that the designed missing part of the skull fits very well with the existing skeletal remains. The final physical assembly of the prototyped element on the damaged skull was tested, restoring it to its whole original shape. Research limitations/implications - The entire process was time-consuming and may be applied just to the most representative skeletal remains. Practical implications - The method allows accurate fabrication of the missing part of the skull to be joined with the original skeletal remains. The advantage of using this technique is that the joining operation can be carried out without any need of supplementary connecting material, such as glue or plaster, to fix together the two parts. Originality/value - The reversible and non-invasive method improves the restoration process, reduces the risk of damage to the skeletal structure and allows reversion to the original repair as it was before. © Emerald Group Publishing Limited.

Keywords: Bones , Computer aided design , Rapid prototyping

Computed tomography is a medical instrument that can be useful not only for diagnostic purposes, but also for surgical planning, thanks to the fact that it offers volumetric information which can be translated in three dimensional models. These models can be visualized, but also exported to Rapid Prototyping (RP) systems, that can produce these structures thanks to the rapidity and versatility of the technologies involved. The literature reports various cases of stereolithographic models used in orthopedic, neurological, and maxillo-facial surgery. In these contexts, the availability of a copy of the real anatomy allows not only planning, but also the practical execution of surgical operations, within the limitations of the materials. Nevertheless, the Rapid Prototyping model also presents some disadvantages that can be reduced if practical simulation is accompanied by virtual simulation, performed on a digital model. The purpose of this work is to examine and present the use of Virtual Reality (VR) and Rapid Prototyping for surgical planning in Maxillo-Facial surgery. ©2008Muntaz B. Habal, MD.

Keywords: Osteogenesis distraction , Rapid prototyping , Reverse engineering , Surgical planning , Virtual reality

Tissue engineered scaffolds must have an organized and repeatable microstructure which enables cells to assemble in an ordered matrix that allows adequate nutriental perfusion. In this work, to evaluate the reciprocal cell interactions of endothelial and osteoblast-like cells, human osteoblast-like cells (MG63) and Human Umbilical Vein Endothelial Cells (HUVEC) were co-seeded onto 3D geometrically controlled porous poly(ε-caprolactone) (PCL) and cultured by means of a rotary cell culture system (RCCS-4DQ). In our dynamic co-culture system, the lack of significant enhancement of osteoblast ALP activity and ECM production indicated that the microgravity conditions of the rotary system affected the cells by favoring their proliferation and cellular cross-talk. These results emphasize how osteoblasts increase endothelial cell proliferate and endothelial cells amplify the growth of osteoblasts but decrease their differentiation. This dynamic seeding of osteoblasts and endothelial cells onto a 3D polymeric scaffold may represent a unique approach for studying the mechanisms of interaction of endothelial and osteoblast cells as well as achieve a functional hybrid in which angiogenesis, furnished by neo-vascular organization of endothelial cells may further support osteoblasts growth. Furthermore, this in vitro model may be useful in examining the applicability of novel material structures for tissue engineering. © SAGE Publications 2008.

Keywords: 3D scaffolds , Dynamic co-culture , Poly-ε- caprolactone , Rapid prototyping , Tissue engineering

The present attention to production cost and time reduction has encouraged many factories to employ some non-conventional technologies instead of the conventional ones for mould production. These specific non-conventional manufacturing technologies, aimed at achieving a significant time reduction for tools manufacturing, are commonly called rapid tooling techniques. Among these rapid tooling methodologies, it is possible to find one of the most direct and flexible techniques which enables, by using a non-cured silicone, the manual shaping of a physical object obtaining directly the mould after some additional handmade refinements. In order to know how the process parameters influence the final shape of the cast object, this work develops an experimental analysis for the estimation of a preliminary model for the process characterization. © 2007 Elsevier B.V. All rights reserved.

Keywords: Rapid prototyping , Rapid tooling , Spin casting