Indirect Additive Manufacturing (AM) of Apatite-Wollastonite (A-W) Glass-Ceramic for Medical Implants

2015 ◽  
Vol 786 ◽  
pp. 354-360 ◽  
Author(s):  
S.F. Khan ◽  
Kenneth W. Dalgarno ◽  
Rakhmad Arief Siregar
Keyword(s):  
Additive Manufacturing ◽  
Glass Ceramic ◽  
Computer Aided Design ◽  
Initial Study ◽  
Patient Specific ◽  
Congenital Defects ◽  
Geometrical Shape ◽  
Medical Implants ◽  
Stl File ◽  
Patient Specific Implants

Bone replacements for congenital defects, cancer resections, and traumas are typically performed using bone grafting. However, due to scarcity of the source material, synthetic materials for bone replacements are sometimes used instead. Unfortunately, the ability to engineer anatomically correct pieces of viable and functional human bone are difficult and time-consuming through conventional manufacturing methods. This paper proposes an alternative route which incorporates the use of AM technology for fabricating patient-specific implants. The implants were computer-aided design (CAD) from a stereolithography (STL) file of a mandible. AM method was combined with lost wax casting (LWC) technology to produce the customised A-W glass-ceramic implants. An initial study of sintered A-W was performed on cylindrical samples show on average 19.8% porous with on average 75% of the porosity being open and an average flexural strength of 82.6 MPa. The A-W scaffolds display a degree of macro-and micro porosity. The geometrical shape of the A-W implants shows a close resemblance to the required implant. Additive manufacturing assisted fabrication of A-W glass-ceramic provides a promising method for manufacturing customised medical implants.

scholarly journals Additive manufacturing in medical sciences: past, present and the future

2018 ◽  
Vol 5 (1) ◽  
pp. 201
Author(s):  
Lakshya P. Rathore ◽  
Naina Verma
Keyword(s):  
Tissue Engineering ◽  
Additive Manufacturing ◽  
Biological Tissue ◽  
Patient Specific ◽  
Basic Fact ◽  
Medical Sciences ◽  
Novel Technique ◽  
Patient Specific Implants ◽  
Tissue Replacement ◽  
The Future

Additive manufacturing (AM) is a novel technique that despite having been around for more than 35 years, has been underutilized. Its great advantage lies in the basic fact that it is incredibly customizable. Since its use was recognized in various fields of medicine like orthopaedics, otorhinolaryngology, ophthalmology etc, it has proved to be one of the most promising developments in most of them. Customizable orthotics, prosthetics and patient specific implants and tracheal splints are few of its advantages. And in the future too, the combination of tissue engineering with AM is believed to produce an immense change in biological tissue replacement.

Increasing Part Accuracy in Additive Manufacturing Processes Using a k-d Tree Based Clustered Adaptive Layering

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Neeraj Panhalkar ◽  
Ratnadeep Paul ◽  
Sam Anand
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Layer By Layer ◽  
Adaptive Slicing ◽  
Stl File ◽  
Build Time ◽  
Standard File Format ◽  
Aided Design ◽  
Profile Errors

Additive manufacturing (AM) is widely used in aerospace, automobile, and medical industries for building highly accurate parts using a layer by layer approach. The stereolithography (STL) file is the standard file format used in AM machines and approximates the three-dimensional (3D) model of parts using planar triangles. However, as the STL file is an approximation of the actual computer aided design (CAD) surface, the geometric errors in the final manufactured parts are pronounced, particularly in those parts with highly curved surfaces. If the part is built with the minimum uniform layer thickness allowed by the AM machine, the manufactured part will typically have the best quality, but this will also result in a considerable increase in build time. Therefore, as a compromise, the part can be built with variable layer thicknesses, i.e., using an adaptive layering technique, which will reduce the part build time while still reducing the part errors and satisfying the geometric tolerance callouts on the part. This paper describes a new approach of determining the variable slices using a 3D k-d tree method. The paper validates the proposed k-d tree based adaptive layering approach for three test parts and documents the results by comparing the volumetric, cylindricity, sphericity, and profile errors obtained from this approach with those obtained using a uniform slicing method. Since current AM machines are incapable of handling adaptive slicing approach directly, a “pseudo” grouped adaptive layering approach is also proposed here. This “clustered slicing” technique will enable the fabrication of a part in bands of varying slice thicknesses with each band having clusters of uniform slice thicknesses. The proposed k-d tree based adaptive slicing approach along with clustered slicing has been validated with simulations of the test parts of different shapes.

scholarly journals Accuracy Assessment of Molded, Patient-Specific Polymethylmethacrylate Craniofacial Implants Compared to Their 3D Printed Originals

2020 ◽  
Vol 9 (3) ◽  
pp. 832 ◽  
Author(s):  
Dave Chamo ◽  
Bilal Msallem ◽  
Neha Sharma ◽  
Soheila Aghlmandi ◽  
Christoph Kunz ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Accuracy Assessment ◽  
Three Dimensional ◽  
Production Costs ◽  
Patient Specific ◽  
Patient Specific Implants ◽  
3D Printed ◽  
Cost Efficient ◽  
Craniofacial Implants ◽  
Aided Design

The use of patient-specific implants (PSIs) in craniofacial surgery is often limited due to a lack of expertise and/or production costs. Therefore, a simple and cost-efficient template-based fabrication workflow has been developed to overcome these disadvantages. The aim of this study is to assess the accuracy of PSIs made from their original templates. For a representative cranial defect (CRD) and a temporo-orbital defect (TOD), ten PSIs were made from polymethylmethacrylate (PMMA) using computer-aided design (CAD) and three-dimensional (3D) printing technology. These customized implants were measured and compared with their original 3D printed templates. The implants for the CRD revealed a root mean square (RMS) value ranging from 1.128 to 0.469 mm with a median RMS (Q1 to Q3) of 0.574 (0.528 to 0.701) mm. Those for the TOD revealed an RMS value ranging from 1.079 to 0.630 mm with a median RMS (Q1 to Q3) of 0.843 (0.635 to 0.943) mm. This study demonstrates that a highly precise duplication of PSIs can be achieved using this template-molding workflow. Thus, virtually planned implants can be accurately transferred into haptic PSIs. This workflow appears to offer a sophisticated solution for craniofacial reconstruction and continues to prove itself in daily clinical practice.

scholarly journals Main Clinical Use of Additive Manufacturing (Three-Dimensional Printing) in Finland Restricted to the Head and Neck Area in 2016–2017

2019 ◽  
Vol 109 (2) ◽  
pp. 166-173 ◽  
Author(s):  
A.B.V. Pettersson ◽  
M. Salmi ◽  
P. Vallittu ◽  
W. Serlo ◽  
J. Tuomi ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Patient Specific ◽  
Future Research ◽  
Imaging Data ◽  
University Hospitals ◽  
Three Dimensional Printing ◽  
Dimensional Printing ◽  
Head Area

Background and Aims: Additive manufacturing or three-dimensional printing is a novel production methodology for producing patient-specific models, medical aids, tools, and implants. However, the clinical impact of this technology is unknown. In this study, we sought to characterize the clinical adoption of medical additive manufacturing in Finland in 2016–2017. We focused on non-dental usage at university hospitals. Materials and Methods: A questionnaire containing five questions was sent by email to all operative, radiologic, and oncologic departments of all university hospitals in Finland. Respondents who reported extensive use of medical additive manufacturing were contacted with additional, personalized questions. Results: Of the 115 questionnaires sent, 58 received answers. Of the responders, 41% identified as non-users, including all general/gastrointestinal (GI) and vascular surgeons, urologists, and gynecologists; 23% identified as experimenters or previous users; and 36% identified as heavy users. Usage was concentrated around the head area by various specialties (neurosurgical, craniomaxillofacial, ear, nose and throat diseases (ENT), plastic surgery). Applications included repair of cranial vault defects and malformations, surgical oncology, trauma, and cleft palate reconstruction. Some routine usage was also reported in orthopedics. In addition to these patient-specific uses, we identified several off-the-shelf medical components that were produced by additive manufacturing, while some important patient-specific components were produced by traditional methodologies such as milling. Conclusion: During 2016–2017, medical additive manufacturing in Finland was routinely used at university hospitals for several applications in the head area. Outside of this area, usage was much less common. Future research should include all patient-specific products created by a computer-aided design/manufacture workflow from imaging data, instead of concentrating on the production methodology.

scholarly journals CAD/CAM Engineered Patient-Specific Impants as a Reposition Device in Le Fort I and Modified Subcondylar Osteotomies: Case Report of Facial Deformity Correction in Acromegaly

2020 ◽  
Vol 13 (3) ◽  
pp. 226-236
Author(s):  
Juho Suojanen ◽  
Zlatan Hodzic ◽  
Tuula Palotie ◽  
Patricia Stoor
Keyword(s):  
Computer Aided Design ◽  
Medical Condition ◽  
Deformity Correction ◽  
Open Bite ◽  
Patient Specific ◽  
Facial Deformity ◽  
Le Fort ◽  
Patient Specific Implants ◽  
Drill Holes ◽  
Le Fort I

Acromegaly is a medical condition where elevated growth hormone or insulin-like growth factor I levels cause several changes in the craniofacial soft and hard features. We report the correction of facial deformity and posterior open bite with Le Fort I and modified subcondylar osteotomies in a patient affected by acromegaly. Computer-aided design and manufacturing generated saw and drill guides were used to perform osteotomies and segment removal. The placement of the patient-specific implants (PSIs) was guided by predesigned drill holes ensuring the required and planned movement of the jaws and position of the PSIs. After segment removal, the PSIs fitted the predesigned drill holes with high precision and were secured without problems. The planned amount of mandibular and maxillary movement was achieved. The occlusion and osteotomies remained stable for the follow-up of 22 months. The use of PSIs combined with guided surgery can be beneficial for selected cases with asymmetry or posterior open bite enabling new approaches and yielding good functional and aesthetic outcome. The modification of conventional ramus osteotomy combined with utilization of ramus segment removal and the use of PSI for reposition is an interesting and promising technique for rare conditions with ramus height asymmetry.

scholarly journals Evolution of design considerations in complex craniofacial reconstruction using patient-specific implants

2016 ◽  
Vol 231 (6) ◽  
pp. 509-524 ◽  
Author(s):  
Sean Peel ◽  
Satyajeet Bhatia ◽  
Dominic Eggbeer ◽  
Daniel S Morris ◽  
Caroline Hayhurst
Keyword(s):  
Additive Manufacturing ◽  
Case Studies ◽  
Computer Aided Design ◽  
Titanium Implants ◽  
Patient Specific ◽  
Patient Case ◽  
Computer Aided Manufacturing ◽  
Design Considerations ◽  
Computer Aided ◽  
Aided Design

Previously published evidence has established major clinical benefits from using computer-aided design, computer-aided manufacturing, and additive manufacturing to produce patient-specific devices. These include cutting guides, drilling guides, positioning guides, and implants. However, custom devices produced using these methods are still not in routine use, particularly by the UK National Health Service. Oft-cited reasons for this slow uptake include the following: a higher up-front cost than conventionally fabricated devices, material-choice uncertainty, and a lack of long-term follow-up due to their relatively recent introduction. This article identifies a further gap in current knowledge – that of design rules, or key specification considerations for complex computer-aided design/computer-aided manufacturing/additive manufacturing devices. This research begins to address the gap by combining a detailed review of the literature with first-hand experience of interdisciplinary collaboration on five craniofacial patient case studies. In each patient case, bony lesions in the orbito-temporal region were segmented, excised, and reconstructed in the virtual environment. Three cases translated these digital plans into theatre via polymer surgical guides. Four cases utilised additive manufacturing to fabricate titanium implants. One implant was machined from polyether ether ketone. From the literature, articles with relevant abstracts were analysed to extract design considerations. In all, 19 frequently recurring design considerations were extracted from previous publications. Nine new design considerations were extracted from the case studies – on the basis of subjective clinical evaluation. These were synthesised to produce a design considerations framework to assist clinicians with prescribing and design engineers with modelling. Promising avenues for further research are proposed.

scholarly journals Additively manufactured versus conventionally pressed cranioplasty implants: An accuracy comparison

2018 ◽  
Vol 232 (9) ◽  
pp. 949-961 ◽  
Author(s):  
Sean Peel ◽  
Dominic Eggbeer ◽  
Hanna Burton ◽  
Hayley Hanson ◽  
Peter L Evans
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Best Practice ◽  
Patient Specific ◽  
Computer Aided ◽  
Design Software ◽  
Uk National Health Service ◽  
Similar Accuracy ◽  
The Uk ◽  
Aided Design

This article compared the accuracy of producing patient-specific cranioplasty implants using four different approaches. Benchmark geometry was designed to represent a cranium and a defect added simulating a craniectomy. An ‘ideal’ contour reconstruction was calculated and compared against reconstructions resulting from the four approaches –‘conventional’, ‘semi-digital’, ‘digital – non-automated’ and ‘digital – semi-automated’. The ‘conventional’ approach relied on hand carving a reconstruction, turning this into a press tool, and pressing titanium sheet. This approach is common in the UK National Health Service. The ‘semi-digital’ approach removed the hand-carving element. Both of the ‘digital’ approaches utilised additive manufacturing to produce the end-use implant. The geometries were designed using a non-specialised computer-aided design software and a semi-automated cranioplasty implant-specific computer-aided design software. It was found that all plates were clinically acceptable and that the digitally designed and additive manufacturing plates were as accurate as the conventional implants. There were no significant differences between the additive manufacturing plates designed using non-specialised computer-aided design software and those designed using the semi-automated tool. The semi-automated software and additive manufacturing production process were capable of producing cranioplasty implants of similar accuracy to multi-purpose software and additive manufacturing, and both were more accurate than handmade implants. The difference was not of clinical significance, demonstrating that the accuracy of additive manufacturing cranioplasty implants meets current best practice.

scholarly journals Imaging, Virtual Planning, Design, and Production of Patient-Specific Implants and Clinical Validation in Craniomaxillofacial Surgery

2012 ◽  
Vol 5 (3) ◽  
pp. 137-143 ◽  
Author(s):  
Per Dérand ◽  
Lars-Erik Rännar ◽  
Jan-M Hirsch
Keyword(s):  
Additive Manufacturing ◽  
Treatment Plan ◽  
Maxillofacial Surgery ◽  
Bone Substitutes ◽  
Patient Specific ◽  
Virtual Design ◽  
Patient Specific Implants ◽  
Cutting Guide ◽  
Ablative Surgery ◽  
Cutting Guides

The purpose of this article was to describe the workflow from imaging, via virtual design, to manufacturing of patient-specific titanium reconstruction plates, cutting guide and mesh, and its utility in connection with surgical treatment of acquired bone defects in the mandible using additive manufacturing by electron beam melting (EBM). Based on computed tomography scans, polygon skulls were created. Following that virtual treatment plans entailing free microvascular transfer of fibula flaps using patient-specific reconstruction plates, mesh, and cutting guides were designed. The design was based on the specification of a Compact UniLOCK 2.4 Large (Synthes®, Switzerland). The obtained polygon plates were bent virtually round the reconstructed mandibles. Next, the resections of the mandibles were planned virtually. A cutting guide was outlined to facilitate resection, as well as plates and titanium mesh for insertion of bone or bone substitutes. Polygon plates and meshes were converted to stereolithography format and used in the software Magics for preparation of input files for the successive step, additive manufacturing. EBM was used to manufacture the customized implants in a biocompatible titanium grade, Ti6Al4V ELI. The implants and the cutting guide were cleaned and sterilized, then transferred to the operating theater, and applied during surgery. Commercially available software programs are sufficient in order to virtually plan for production of patient-specific implants. Furthermore, EBM-produced implants are fully usable under clinical conditions in reconstruction of acquired defects in the mandible. A good compliance between the treatment plan and the fit was demonstrated during operation. Within the constraints of this article, the authors describe a workflow for production of patient-specific implants, using EBM manufacturing. Titanium cutting guides, reconstruction plates for fixation of microvascular transfer of osteomyocutaneous bone grafts, and mesh to replace resected bone that can function as a carrier for bone or bone substitutes were designed and tested during reconstructive maxillofacial surgery. A clinically fit, well within the requirements for what is needed and obtained using traditional free hand bending of commercially available devices, or even higher precision, was demonstrated in ablative surgery in four patients.

scholarly journals Applications of 3D Planning, Plastic Materials and Additive Manufacturing in Functional Rehabilitations in the Head and Neck Surgery

2018 ◽  
Vol 55 (3) ◽  
pp. 431-433
Author(s):  
Gheorghe Muhlfay ◽  
Zoltan Fabian ◽  
Radu Neagoe ◽  
Karin Ursula Horvath
Keyword(s):  
Additive Manufacturing ◽  
Surgical Planning ◽  
Standard Of Care ◽  
Neck Surgery ◽  
Patient Specific ◽  
Patient Specific Implants ◽  
Planning Software ◽  
Plastic Materials ◽  
Potential Benefits ◽  
Manufacturing Technologies

The developments in the biocompatible materials and additive manufacturing technologies gave birth to new possibilities in reconstructive surgery. In addition to revolutionizing the diagnostic possibilities, the modern medical imaging has led to the development of surgical planning software. Using these state-of-the-art technologies, a new standard of care is rising with the spread of patient specific implants. Our view in studying and using these materials and technologies goes beyond their biocompatibility, focusing on the functional and esthetic impact of these restorations. Our aim is to show their potential benefits and pitfalls presenting a couple of posttraumatic and oncological application possibilities, focusing on the new presurgical planning, choice of materials and manufacturing technologies.

Additive Manufacturing Distortion Compensation Based on Scan Data of Built Geometry

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Matthew McConaha ◽  
Sam Anand
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Thermal Gradients ◽  
Distortion Compensation ◽  
Stl File ◽  
Data Points ◽  
Part Distortion ◽  
Scan Data ◽  
Aided Design ◽  
Am Processes

Abstract Additive manufacturing (AM) processes such as direct metal laser sintering (DMLS) are highly attractive manufacturing processes due to the ability to create certain geometries which would be prohibitive or even impossible to manufacture by other means. However, with such high thermal gradients which are usually present in these processes, manufacturing distortions may result in the creation of unacceptable parts. This paper presents an approach to compensate input STL files based on registration of the point cloud from sacrificial part builds. A novel strain energy based non-rigid registration algorithm has been developed for robust registration of data points to the original computer-aided design (CAD) model. A neural network based approach is used to learn the deformation of the geometry based on the deviation of the scan geometry. This network is subsequently used to modify the STL file to generate a new compensated STL file. The compensated STL file was validated by building parts and comparing the change in the part distortion.

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