ADDITIVELY MANUFACTURED CUSTOM LOAD-BEARING IMPLANTABLE DEVICES

Microfabrication approaches for oral research and clinical dentistry

Currently, there is a variety of laboratory tools and strategies that have been developed to investigate in-vivo processes using in-vitro models. Amongst these, microfabrication represents a disruptive technology that is currently enabling next-generation biomedical research through the development of complex laboratory approaches (e.g., microfluidics), engineering of micrometer scale sensors and actuators (micropillars for traction force microscopy), and the creation of environments mimicking cell, tissue, and organ-specific contexts. Although microfabrication has been around for some time, its application in dental and oral research is still incipient. Nevertheless, in recent years multiple lines of research have emerged that use microfabrication-based approaches for the study of oral diseases and conditions with micro- and nano-scale sensitivities. Furthermore, many investigations are aiming to develop clinically relevant microfabrication-based applications for diagnostics, screening, and oral biomaterial manufacturing. Therefore, the objective of this review is to summarize the current application of microfabrication techniques in oral sciences, both in research and clinics, and to discuss possible future applications of these technologies for in-vitro studies and practical patient care. Initially, this review provides an overview of the most employed microfabrication methods utilized in biomedicine and dentistry. Subsequently, the use of micro- and nano-fabrication approaches in relevant fields of dental research such as endodontic and periodontal regeneration, biomaterials research, dental implantology, oral pathology, and biofilms was discussed. Finally, the current and future uses of microfabrication technology for clinical dentistry and how these approaches may soon be widely available in clinics for the diagnosis, prevention, and treatment of relevant pathologies are presented.

Advances in additive manufacturing processes and their use for the fabrication of lower limb prosthetic devices

INTRODUCTION

Traditional methods of prosthesis fabrication are not efficient and user centric and are made for common purposes without focusing on individual demands of user which leads to rejection of prosthesis for long-term use. Utilizing advanced additive manufacturing techniques for fabrication of prosthesis makes the development process user centric and covers all the user demands thus providing better fit, comfort, and more stable gait rehabilitation for the user.

AREAS COVERED

The articles reporting fabrication of lower limb prosthesis and its socket are included in the study. Standard fabrication and additive manufacturing method are both systematically assessed by the reviewers. The review also covers the advanced methods of additive manufacturing that are presently being used for fabrication of rehabilitation devices.

EXPERT OPINION

Additive manufacturing method of fabrication of prosthesis provides more flexibility for manufacturing prosthesis parts as per demand of the user. The fabrication method takes into account the residual limb and thus makes the prosthesis user-specific providing better comfort and fit.

Review on 3D printing in dentistry: conventional to personalized dental care

The CAD (Computer-aided design) and CAM (computer-aided manufacturing) have most applications in the manufacturing of fully automated, personalized dental devices and tailor-made treatment plans. 3D printing is one of the most rapidly expanding and new methods of manufacturing different things because of its on-demand and high productivity within the cost-effective manner which have a variety of applications in healthcare, pharmaceuticals, orthopaedics, engineered tissue models, medical devices, defence industries, automotive and aerospace sectors. Due to its emerging applications in the various sectors, the healthcare, Industries, and academic sectors are attracted towards the 3D printed materials. This review talks about the dental implants, polymers that are employed in concocting dental implants, critical parameters, and challenges which are to be considered while preparing these implants, advantages of 3D printing in the field of dentistry and the current trends. it discusses the variety of applications of 3D printed materials in the field of dentistry. Along with their method of fabrication, their critical process parameters (CPPs) are also discussed.

Knowledge on Applications of 3D Design and Printing in Dentistry Among Dental Practitioners in Saudi Arabia: A Questionnaire-Based Survey

Background: This knowledge, attitude, and practices (KAP) survey will provide baseline data and identify gaps that may facilitate understanding and further action to plan, implement, and evaluate practice toward 3D-printing technology among dental practitioners in Saudi Arabia.

AIMS AND OBJECTIVES

The present study aims to assess dental practitioners' self-reported knowledge, attitude, and practice of 3D printing in Saudi Arabia.

METHODOLOGY

A cross-sectional, closed-ended questionnaire of registered dental practitioners in Saudi Arabia was conducted. A sample size of 156 was considered for analysis. After obtaining approval from the Institutional Review Board, Riyadh Elm University, the research was conducted during the month of April 2022 amongst 154 registered dental practitioners. The research was distributed among dental health specialists either working in dental colleges, dental clinics, or both in government as well as private settings. Dentists who were not actively involved in 3D printing were excluded. SPSS software, version 25.0, (IBM Corp., Armonk, NY) was used to analyze the data.

RESULTS AND CONCLUSION

Of all dentists included in the study, 98% were found to be aware that 3D printing in dentistry is used in Saudi Arabia and 2 % were not aware of its usage in Saudi Arabia. In total, 78.60% of the dentists felt that 3D-printed implant guides made the placement of implants the most accurate and least complicated procedure, and 21.40% of the dentists felt it was the least accurate and most complicated procedure.

A Review of 3D Printing in Dentistry: Technologies, Affecting Factors, and Applications

Three-dimensional (3D) printing technologies are advanced manufacturing technologies based on computer-aided design digital models to create personalized 3D objects automatically. They have been widely used in the industry, design, engineering, and manufacturing fields for nearly 30 years. Three-dimensional printing has many advantages in process engineering, with applications in dentistry ranging from the field of prosthodontics, oral and maxillofacial surgery, and oral implantology to orthodontics, endodontics, and periodontology. This review provides a practical and scientific overview of 3D printing technologies. First, it introduces current 3D printing technologies, including powder bed fusion, photopolymerization molding, and fused deposition modeling. Additionally, it introduces various factors affecting 3D printing metrics, such as mechanical properties and accuracy. The final section presents a summary of the clinical applications of 3D printing in dentistry, including manufacturing working models and main applications in the fields of prosthodontics, oral and maxillofacial surgery, and oral implantology. The 3D printing technologies have the advantages of high material utilization and the ability to manufacture a single complex geometry; nevertheless, they have the disadvantages of high cost and time-consuming postprocessing. The development of new materials and technologies will be the future trend of 3D printing in dentistry, and there is no denying that 3D printing will have a bright future.

Exploring Macroporosity of Additively Manufactured Titanium Metamaterials for Bone Regeneration with Quality by Design: A Systematic Literature Review

Additive manufacturing facilitates the design of porous metal implants with detailed internal architecture. A rationally designed porous structure can provide to biocompatible titanium alloys biomimetic mechanical and biological properties for bone regeneration. However, increased porosity results in decreased material strength. The porosity and pore sizes that are ideal for porous implants are still controversial in the literature, complicating the justification of a design decision. Recently, metallic porous biomaterials have been proposed for load-bearing applications beyond surface coatings. This recent science lacks standards, but the Quality by Design (QbD) system can assist the design process in a systematic way. This study used the QbD system to explore the Quality Target Product Profile and Ideal Quality Attributes of additively manufactured titanium porous scaffolds for bone regeneration with a biomimetic approach. For this purpose, a total of 807 experimental results extracted from 50 different studies were benchmarked against proposed target values based on bone properties, governmental regulations, and scientific research relevant to bone implants. The scaffold properties such as unit cell geometry, pore size, porosity, compressive strength, and fatigue strength were studied. The results of this study may help future research to effectively direct the design process under the QbD system.

Optimization Methodology for Additive Manufacturing of Customized Parts by Fused Deposition Modeling (FDM). Application to a Shoe Heel

Additive manufacturing technologies offer important new manufacturing possibilities, but its potential is so big that only with the support of other technologies can it really be exploited. In that sense, parametric design and design optimization tools appear as two appropriate complements for additive manufacturing. Synergies existing between these three technologies allow for integrated approaches to the design of customized and optimized products. While additive manufacturing makes it possible to materialize overly complex geometries, parametric design allows designs to be adapted to custom characteristics and optimization helps to choose the best solution according to the objectives. This work represents an application development of a previous work published in Polymers which exposed the general structure, operation and opportunities of a methodology that integrates these three technologies by using visual programming with Grasshopper. In this work, the different stages of the methodology and the way in which each one modifies the final design are exposed in detail, applying it to a case study: the design of a shoe heel for FDM—an interesting example both from the perspectives of ergonomic and mass customization. Programming, operation and results are exposed in detail showing the complexity, usefulness and potential of the methodology, with the aim of helping other researchers to develop proposals in this line.

Integration of Additive Manufacturing, Parametric Design, and Optimization of Parts Obtained by Fused Deposition Modeling (FDM). A Methodological Approach

The use of current computer tools in both manufacturing and design stages breaks with the traditional conception of productive process, including successive stages of projection, representation, and manufacturing. Designs can be programmed as problems to be solved by using computational tools based on complex algorithms to optimize and produce more effective solutions. Additive manufacturing technologies enhance these possibilities by providing great geometric freedom to the materialization phase. This work presents a design methodology for the optimization of parts produced by additive manufacturing and explores the synergies between additive manufacturing, parametric design, and optimization processes to guide their integration into the proposed methodology. By using Grasshopper, a visual programming application, a continuous data flow for parts optimization is defined. Parametric design tools support the structural optimization of the general geometry, the infill, and the shell structure to obtain lightweight designs. Thus, the final shapes are obtained as a result of the optimization process which starts from basic geometries, not from an initial design. The infill does not correspond to pre-established patterns, and its elements are sized in a non-uniform manner throughout the piece to respond to different local loads. Mass customization and Fused Deposition Modeling (FDM) systems represent contexts of special potential for this methodology.

A New Generation of Bio-Composite Thermoplastic Filaments for a More Sustainable Design of Parts Manufactured by FDM

The most recent developments of Fused Deposition Modelling (FDM) techniques are moving the application of Additive Manufacturing (AM) technologies toward new areas of investigation such as the biomedical, aerospace, and marine engineering in addition to the more consolidated industrial and civil fields. Some specific characteristics are required for the components designed for peculiar applications, such as complex geometries, lightweight, and high strength as well as breathability and aesthetic appearance specifically in the biomedical field. All these design specifications could be potentially satisfied by manufacturing with 3D printing techniques. Moreover, the development of purpose-dedicated filaments can be considered a key factor to successfully meet all the requirements. In this paper, fabrication and applications of five new thermoplastic materials with fillers are described and analyzed. They are organic bio-plastic compounds made of polylactic acid (PLA) and organic by-products. The growing interest in these new composite materials reinforced with organic by-products is due to the reduction of production management costs and their low environmental impact. In this study, the production workflow has been set up and described in detail. The main properties of these new thermoplastic materials have been analyzed with a major emphasis on strength, lightweight, and surface finish. The analysis showed that these materials can be particularly suitable for biomedical applications. Therefore, two different biomedical devices were selected and relative prototypes were manufactured with one of the analyzed thermoplastic materials. The feasibility, benefits, and performance of the thermoplastic material considered for these applications were successfully assessed.

Prosthetic Hip ROM from Multibody Software Simulation

The pre-operative planning of a hip arthroplasty entails the choice of the prosthetic hip model and of the position of both joint components with reference to bone. Assessing the impact of geometrical factors on the final hip range of motion (ROM) is not trivial, since it requires performing 3D evaluations. Nonetheless, it deserves to be studied since hip impingement and dislocation are still relevant complications in hip arthroplasty. This work pertains a numerical model for the assessment of the hip ROM in relation to cotyle position. External/internal rotation is considered as a benchmark, and multiple combinations of acetabular anteversion/inclination are considered. According to results, over two hundred different geometric configurations can be examined in few minutes, and the cotyle position can be so optimized with relevant benefits in term of hip ROM.

Use of Three-dimensional Printing in the Development of Optimal Cardiac CT Scanning Protocols

Three-dimensional (3D) printing is increasingly used in medical applications with most of the studies focusing on its applications in medical education and training, pre-surgical planning and simulation, and doctor-patient communication. An emerging area of utilising 3D printed models lies in the development of cardiac computed tomography (CT) protocols for visualisation and detection of cardiovascular disease. Specifically, 3D printed heart and cardiovascular models have shown potential value in the evaluation of coronary plaques and coronary stents, aortic diseases and detection of pulmonary embolism. This review article provides an overview of the clinical value of 3D printed models in these areas with regard to the development of optimal CT scanning protocols for both diagnostic evaluation of cardiovascular disease and reduction of radiation dose. The expected outcomes are to encourage further research towards this direction.

Experimental Validation of an ITAP Numerical Model and the Effect of Implant Stem Stiffness on Bone Strain Energy

The Intraosseous Transcutaneous Amputation Prosthesis (ITAP) offers transfemoral amputees an ambulatory method potentially reducing soft tissue complications seen with socket and stump devices. This study validated a finite element (in silico) model based on an ITAP design and investigated implant stem stiffness influence on periprosthetic femoral bone strain. Results showed good agreement in the validation of the in silico model against the in vitro results using uniaxial strain gauges and Digital Image Correlation (DIC). Using Strain Energy Density (SED) thresholds as the stimulus for adaptive bone remodelling, the validated model illustrated that: (a) bone apposition increased and resorption decreased with increasing implant stem flexibility in early stance; (b) bone apposition decreased (mean change = − 9.8%) and resorption increased (mean change = 20.3%) from distal to proximal in most stem stiffness models in early stance. By engineering the flow of force through the implant/bone (e.g. by changing material properties) these results demonstrate how periprosthetic bone remodelling, thus aseptic loosening, can be managed. This paper finds that future implant designs should be optimised for bone strain under a variety of relevant loading conditions using finite element models to maximise the chances of clinical success.

Partial Bone Formation in Additive Manufactured Porous Implants Reduces Predicted Stress and Danger of Fatigue Failure

New porous implant designs made possible by additive manufacturing allow for increased osseointegration, potentially improving implant performance and longevity for patients that require massive bone implants. The aim of this study was to evaluate how implantation and the strain distribution in the implant affect the pattern of bone ingrowth and how changes in tissue density within the pores alter the stresses in implants. The hypothesis was that porous metal implants are susceptible to fatigue failure, and that this reduces as osteointegration occurs. A phenomenological, finite element analysis (FEA) bone remodelling model was used to predict partial bone formation for two porous (pore sizes of 700 μm and 1500 μm), laser sintered Ti₆Al₄V implants in an ovine condylar defect model, and was compared and verified against in vivo, histology results. The FEA models predicted partial bone formation within the porous implants, but over-estimated the amount of bone-surface area compared to histology results. The stress and strain in the implant and adjacent tissues were assessed before, during bone remodelling, and at equilibrium. Results showed that partial bone formation improves the stress distribution locally by reducing stress concentrations for both pore sizes, by at least 20%. This improves the long-term fatigue resistance for the larger pore implant, as excessively high stress is reduced to safer levels (86% of fatigue strength) as bone forms. The stress distribution only changed slightly in regions without bone growth. As the extent of bone formation into extensively porous bone implants depends on the level of stress shielding, the design of the implant and stiffness have significant influence on bone integration and need to be considered carefully to ensure the safety of implants with substantial porous regions. To our knowledge this is the first time that the effect of bone formation on stress distribution within a porous implant has been described and characterised.

Application of 3D Printing Technology for Design and Manufacturing of Customized Components for a Mechanical Stretching Bioreactor

Three-dimensional (3D) printing represents a key technology for rapid prototyping, allowing easy, rapid, and low-cost fabrication. In this work, 3D printing was applied for the in-house production of customized components of a mechanical stretching bioreactor with potential application for cardiac tissue engineering and mechanobiology studies. The culture chamber housing and the motor housing were developed as functional permanent parts, aimed at fixing the culture chamber position and at guaranteeing motor watertightness, respectively. Innovative sample holder prototypes were specifically designed and 3D-printed for holding thin and soft biological samples during cyclic stretch culture. The manufactured components were tested in-house and in a cell biology laboratory. Moreover, tensile tests and finite element analysis were performed to investigate the gripping performance of the sample holder prototypes. All the components showed suitable performances in terms of design, ease of use, and functionality. Based on 3D printing, the bioreactor optimization was completely performed in-house, from design to fabrication, enabling customization freedom, strict design-to-prototype timing, and cost and time effective testing, finally boosting the bioreactor development process.

A New Method for Biostatistical miRNA Pattern Recognition with Topological Properties of Visibility Graphs in 3D Space

Visibility is a very important topic in computer graphics and especially in calculations of global illumination. Visibility determination, the process of deciding which surface can be seen from a certain point, has also problematic applications in biomedical engineering. The problem of visibility computation with mathematical tools can be presented as a visibility network. Instead of utilizing a 2D visibility network or graphs whose construction is well known, in this paper, a new method for the construction of 3D visibility graphs will be proposed. Drawing graphs as nodes connected by links in a 3D space is visually compelling but computationally difficult. Thus, the construction of 3D visibility graphs is highly complex and requires professional computers or supercomputers. A new method for optimizing the algorithm visibility network in a 3D space and a new method for quantifying the complexity of a network in DNA pattern recognition in biomedical engineering have been developed. Statistical methods have been used to calculate the topological properties of a visibility graph in pattern recognition. A new n-hyper hybrid method is also used for combining an intelligent neural network system for DNA pattern recognition with the topological properties of visibility networks of a 3D space and for evaluating its prospective use in the prediction of cancer.

Additive Manufacturing Applications on Flexible Actuators for Active Orthoses and Medical Devices

This paper describes the results of research projects developed at the University of L'Aquila by the research group of the authors in the field of biomedical engineering, which have seen an important use of additive manufacturing technologies in the prototyping step and, in some cases, also for the realization of preindustrialization prototypes. For these projects, commercial 3D printers and technologies such as fused deposition modelling (FDM) were used; the most commonly used polymers in these technologies are acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA). The research projects concern the development of innovative actuators, such as pneumatic muscles and soft pneumatic actuators (SPAs), the development of active orthoses, such as a lower limb orthosis and, finally, the development of a variable-stiffness grasper to be used in natural orifice transluminal endoscopic surgery (NOTES). The main aspects of these research projects are described in the paper, highlighting the technologies used such as the finite element analysis and additive manufacturing.

Robocasting of Bioactive SiO2-P2O5-CaO-MgO-Na2O-K2O Glass Scaffolds

Bioactive silicate glass scaffolds were fabricated by a robocasting process in which all the movements of the printing head were programmed by compiling a script (text file). A printable ink made of glass powder and Pluronic F-127, acting as a binder, was extruded to obtain macroporous scaffolds with a grid-like three-dimensional structure. The scaffold architecture was investigated by scanning electron microscopy and microtomographic analysis, which allowed quantifying the microstructural parameters (pore size 150-180 μm and strut diameter 300 μm). In vitro tests in simulated body fluid (SBF) confirmed the apatite-forming ability (i.e., bioactivity) of the scaffolds. The compressive strength (around 10 MPa for as-produced scaffolds) progressively decreased during immersion in SBF (3.3 MPa after 4 weeks) but remains acceptable for bone repair applications. Taken together, these results (adequate porosity and mechanical strength as well as bioactivity) support the potential suitability of the prepared scaffolds for bone substitution.

The Role of 3D Printing in Medical Applications: A State of the Art

Three-dimensional (3D) printing refers to a number of manufacturing technologies that generate a physical model from digital information. Medical 3D printing was once an ambitious pipe dream. However, time and investment made it real. Nowadays, the 3D printing technology represents a big opportunity to help pharmaceutical and medical companies to create more specific drugs, enabling a rapid production of medical implants, and changing the way that doctors and surgeons plan procedures. Patient-specific 3D-printed anatomical models are becoming increasingly useful tools in today's practice of precision medicine and for personalized treatments. In the future, 3D-printed implantable organs will probably be available, reducing the waiting lists and increasing the number of lives saved. Additive manufacturing for healthcare is still very much a work in progress, but it is already applied in many different ways in medical field that, already reeling under immense pressure with regards to optimal performance and reduced costs, will stand to gain unprecedented benefits from this good-as-gold technology. The goal of this analysis is to demonstrate by a deep research of the 3D-printing applications in medical field the usefulness and drawbacks and how powerful technology it is.

Design of Additively Manufactured Structures for Biomedical Applications: A Review of the Additive Manufacturing Processes Applied to the Biomedical Sector

Additive manufacturing (AM) is a disruptive technology as it pushes the frontier of manufacturing towards a new design perspective, such as the ability to shape geometries that cannot be formed with any other traditional technique. AM has today shown successful applications in several fields such as the biomedical sector in which it provides a relatively fast and effective way to solve even complex medical cases. From this point of view, the purpose of this paper is to illustrate AM technologies currently used in the medical field and their benefits along with contemporary. The review highlights differences in processes, materials, and design of additive manufacturing techniques used in biomedical applications. Successful case studies are presented to emphasise the potentiality of AM processes. The presented review supports improvements in materials and design for future researches in biomedical surgeries using instruments and implants made by AM.

Digital Design of Medical Replicas via Desktop Systems: Shape Evaluation of Colon Parts

In this paper, we aim at providing results concerning the application of desktop systems for rapid prototyping of medical replicas that involve complex shapes, as, for example, folds of a colon. Medical replicas may assist preoperative planning or tutoring in surgery to better understand the interaction among pathology and organs. Major goals of the paper concern with guiding the digital design workflow of the replicas and understanding their final performance, according to the requirements asked by the medics (shape accuracy, capability of seeing both inner and outer details, and support and possible interfacing with other organs). In particular, after the analysis of these requirements, we apply digital design for colon replicas, adopting two desktop systems. The experimental results confirm that the proposed preprocessing strategy is able to conduct to the manufacturing of colon replicas divided in self-supporting segments, minimizing the supports during printing. This allows also to reach an acceptable level of final quality, according to the request of having a 3D presurgery overview of the problems. These replicas are compared through reverse engineering acquisitions made by a structured-light system, to assess the achieved shape and dimensional accuracy. Final results demonstrate that low-cost desktop systems, coupled with proper strategy of preprocessing, may have shape deviation in the range of ±1 mm, good for physical manipulations during medical diagnosis and explanation.

Innovative Methodology of On-Line Point Cloud Data Compression for Free-Form Surface Scanning Measurement

In order to obtain a highly accurate profile of a measured three-dimensional (3D) free-form surface, a scanning measuring device has to produce extremely dense point cloud data with a great sampling rate. Bottlenecks are created owing to inefficiencies in manipulating, storing and transferring these data, and parametric modelling from them is quite time-consuming work. In order to effectively compress the dense point cloud data obtained from a 3D free-form surface during the real-time scanning measuring process, this paper presents an innovative methodology of an on-line point cloud data compression algorithm for 3D free-form surface scanning measurement. It has the ability to identify and eliminate data redundancy caused by geometric feature similarity between adjacent scanning layers. At first, the new algorithm adopts the bi-Akima method to compress the initial point cloud data; next, the data redundancy existing in the compressed point cloud is further identified and eliminated; then, we can get the final compressed point cloud data. Finally, the experiment is conducted, and the results demonstrate that the proposed algorithm is capable of obtaining high-quality data compression results with higher data compression ratios than other existing on-line point cloud data compression/reduction methods.

3D Printed Anatomy-Specific Fixture for Consistent Glenoid Cavity Position in Shoulder Simulator

Purpose

Fixation methods for consistent anatomical structure positioning in biomechanical testing can be challenging. Image-based 3D printing is an attractive method for fabrication of biomechanical supports of anatomical structure due to its ability to precisely locate anatomical features with respect to the loading system.

Method

A case study is presented to provide a design guide for fixation block fabrication. The anatomy of interest was CT scanned and reconstructed in 3D. The model was imported into commercially available CAD software and modified into a solid object and to create the fixture block. The CAD fixture block is standardized such that anatomical features are always in the same position for the testing system by subtracting the anatomy from a base fixture block.

Results

This method allowed a strong immobilization of anatomical specimens and a controlled and consistent positioning feature with respect to the testing system. Furthermore, the fixture block can be easily modified and adapted to anatomical structures of interest using CAD software.

Conclusion

This approach allows preservation of the bony anatomy integrity and provides a repeatable and consistent anatomical positioning with respect to the testing system. It can be adapted for other anatomical structures in various other biomechanical settings.

Compatibility of a Silicone Impression/Adhesive System to FDM-Printed Tray Materials-A Laboratory Peel-off Study

Computer-aided design (CAD) and additive manufacturing (AM) have shown promise in facilitating the fabrication of custom trays. Due to the clinical requirements, custom tray materials should achieve good bonding to the impression/adhesive systems. This study evaluated the retention of three fused deposition modeling (FDM) custom tray materials to a silicone impression/adhesive system before and after gritblasting (GB) by peel-off test. CAD-designed experimental test blocks were printed by FDM using acrylonitrile butadiene styrene (ABS), polyethylene terephthalate glycol copolyester (PETG), and high impact polystyrene (HIPS), and the reference test blocks were made of a conventional light-curing resin (n = 11). Before and after GB, the surface topography of all tray materials was analysed, and the maximum strength of the test block peeled off from a silicone impression/adhesive system was measured. After GB, the arithmetic mean height (Sa) and the valley fluid retention index (Svi) of the four material groups declined (p < 0.05). The peel-off strength of each of the four material groups significantly decreased by GB (p < 0.05), but no statistical difference could be found among them before or after GB. In all peel-off tests, adhesive failure occurred at the adhesive-impression material interface. The results indicated ABS, HIPS, and PETG could provide sufficient adhesion to the adhesive as the conventional light-curing resin, and GB could reduce the roughness generated by FDM and weaken the bonding between the adhesive and the silicone impression.

An Ergonomic Customized-Tool Handle Design for Precision Tools using Additive Manufacturing: A Case Study

A study was carried out with 135 surgeons to obtain a surgical laparoscopic grasper handle design that adapts to the size of each surgeon’s hand, in a functionally appropriate way, and has the sufficient ergonomics to avoid generating the problems detected nowadays. The main conclusion of the work is the practical 3D parametric design obtained for a laparoscopic surgical graspers handle that is scalable to fit each particular surgeon's hand size. In addition, it has been possible to determine that the anthropometric measure of the surgeon's hand defined as Palm Length Measured (PLM) allows the design of the 3D parametric model of the surgical handle to be conveniently scaled. The results show that both additive manufacturing and the application of ergonomics criterion provide an efficient method for the custom design and manufacture of this type of specialised tool, with potential application in other sectors.

Clinical Assessment of Dental Implant Stability During Follow-Up: What Is Actually Measured, and Perspectives

The optimization of loading protocols following dental implant insertion requires setting up patient-specific protocols, customized according to the actual implant osseointegration, measured through quantitative, objective methods. Various devices for the assessment of implant stability as an indirect measure of implant osseointegration have been developed. They are analyzed here, introducing the respective physical models, outlining major advantages and critical aspects, and reporting their clinical performance. A careful discussion of underlying hypotheses is finally reported, as is a suggestion for further development of instrumentation and signal analysis.