Computer aided modelling to simulate the biomechanical behaviour of customised orthodontic removable appliances

In the field of orthodontics, the use of Removable Thermoplastic Appliances (RTAs) to treat moderate malocclusion problems is progressively replacing traditional fixed brackets. Generally, these orthodontic devices are designed on the basis of individual anatomies and customised requirements. However, many elements may affect the effectiveness of a RTA-based therapy: accuracies of anatomical reference models, clinical treatment strategies, shape features and mechanical properties of the appliances. In this paper, a numerical model for customised orthodontic treatments planning is proposed by means of the finite element method. The model integrates individual patient’s teeth, periodontal ligaments, bone tissue with structural and geometrical attributes of the appliances. The anatomical tissues are reconstructed by a multi-modality imaging technique, which combines 3D data obtained by an optical scanner (visible tissues) and a computerised tomography system (internal tissues). The mechanical interactions between anatomical shapes and appliance models are simulated through finite element analyses. The numerical approach allows a dental technician to predict how the RTA attributes affect tooth movements. In this work, treatments considering rotation movements for a maxillary incisor and a maxillary canine have been analysed by using multi-tooth models

Designing of Customized Devices in Orthodontics by Digital Imaging and CAD/FEM Modeling

In current decade, patient’s demand of minimal orthodontic treatment have encouraged the introduction of appliance that will be lighter, improved profile and better esthetics with regard to conventional orthodontic treatment. Considering aesthetic treatment options, removable clear aligner treatment got popular among patients since it allows clinician to deliver comprehensive orthodontic treatment while maintaining comfort of patient. The aligners should exert an adequate force in order to shift the tooth to a desirable position. But, in recent times, the relation of applied force and aligner property (eg. thickness) is inadequately witnessed. This article focuses on a patient-focused framework has been formulated which depicts orthodontic movement of teeth with the help of aligners. Particularly, a finite element model is being formulated which optimizes the thickness of these aligners with respect to amount of force and moment system applied to a lower central incisor while tipping it bucco-lingually

Computational design and engineering of polymeric orthodontic aligners

Transparent and removable aligners represent an effective solution to correct various orthodontic malocclusions through minimally invasive procedures. An aligner-based treatment requires patients to sequentially wear dentition-mating shells obtained by thermoforming polymeric disks on reference dental models. An aligner is shaped introducing a geometrical mismatch with respect to the actual tooth positions to induce a loading system, which moves the target teeth toward the correct positions. The common practice is based on selecting the aligner features (material, thickness, and auxiliary elements) by only considering clinician's subjective assessments. In this article, a computational design and engineering methodology has been developed to reconstruct anatomical tissues, to model parametric aligner shapes, to simulate orthodontic movements, and to enhance the aligner design. The proposed approach integrates computer-aided technologies, from tomographic imaging to optical scanning, from parametric modeling to finite element analyses, within a 3-dimensional digital framework. The anatomical modeling provides anatomies, including teeth (roots and crowns), jaw bones, and periodontal ligaments, which are the references for the down streaming parametric aligner shaping. The biomechanical interactions between anatomical models and aligner geometries are virtually reproduced using a finite element analysis software. The methodology allows numerical simulations of patient-specific conditions and the comparative analyses of different aligner configurations. In this article, the digital framework has been used to study the influence of various auxiliary elements on the loading system delivered to a maxillary and a mandibular central incisor during an orthodontic tipping movement. Numerical simulations have shown a high dependency of the orthodontic tooth movement on the auxiliary element configuration, which should then be accurately selected to maximize the aligner's effectiveness

A review of image-based simulation applications in high-value manufacturing

Image-Based Simulation (IBSim) is the process by which a digital representation of a real geometry is generated from image data for the purpose of performing a simulation with greater accuracy than with idealised Computer Aided Design (CAD) based simulations. Whilst IBSim originates in the biomedical field, the wider adoption of imaging for non-destructive testing and evaluation (NDT/NDE) within the High-Value Manufacturing (HVM) sector has allowed wider use of IBSim in recent years. IBSim is invaluable in scenarios where there exists a non-negligible variation between the ‘as designed’ and ‘as manufactured’ state of parts. It has also been used for characterisation of geometries too complex to accurately draw with CAD. IBSim simulations are unique to the geometry being imaged, therefore it is possible to perform part-specific virtual testing within batches of manufactured parts. This novel review presents the applications of IBSim within HVM, whereby HVM is the value provided by a manufactured part (or conversely the potential cost should the part fail) rather than the actual cost of manufacturing the part itself. Examples include fibre and aggregate composite materials, additive manufacturing, foams, and interface bonding such as welding. This review is divided into the following sections: Material Characterisation; Characterisation of Manufacturing Techniques; Impact of Deviations from Idealised Design Geometry on Product Design and Performance; Customisation and Personalisation of Products; IBSim in Biomimicry. Finally, conclusions are drawn, and observations made on future trends based on the current state of the literature

Advanced Applications of Rapid Prototyping Technology in Modern Engineering

Rapid prototyping (RP) technology has been widely known and appreciated due to its flexible and customized manufacturing capabilities. The widely studied RP techniques include stereolithography apparatus (SLA), selective laser sintering (SLS), three-dimensional printing (3DP), fused deposition modeling (FDM), 3D plotting, solid ground curing (SGC), multiphase jet solidification (MJS), laminated object manufacturing (LOM). Different techniques are associated with different materials and/or processing principles and thus are devoted to specific applications. RP technology has no longer been only for prototype building rather has been extended for real industrial manufacturing solutions. Today, the RP technology has contributed to almost all engineering areas that include mechanical, materials, industrial, aerospace, electrical and most recently biomedical engineering. This book aims to present the advanced development of RP technologies in various engineering areas as the solutions to the real world engineering problems

Study of medical image data transformation techniques and compatibility analysis for 3D printing

Various applications exist for additive manufacturing (AM) and reverse engineering (RE) within the medical sector. One of the significant challenges identified in the literature is the accuracy of 3D printed medical models compared to their original CAD models. Some studies have reported that 3D printed models are accurate, while others claim the opposite. This thesis aims to highlight the medical applications of AM and RE, study medical image reconstruction techniques into a 3D printable file format, and the deviations of a 3D printed model using RE. A case study on a human femur bone was conducted through medical imaging, 3D printing, and RE for comparative deviation analysis. In addition, another medical application of RE has been presented, which is for solid modelling. Segmentation was done using opensource software for trial and training purposes, while the experiment was done using commercial software. The femur model was 3D printed using an industrial FDM printer. Three different non-contact 3D scanners were investigated for the RE process. Post-processing of the point cloud was done in the VX Elements software environment, while mesh analysis was conducted in MeshLab. The scanning performance was measured using the VX Inspect environment and MeshLab. Both relative and absolute metrics were used to determine the deviation of the scanned models from the reference mesh. The scanners' range of deviations was approximately from -0.375 mm to 0.388 mm (range of about 0.763mm) with an average RMS of about 0.22 mm. The results showed that the mean deviation of the 3D printed model (based on 3D scanning) has an average range of about 0.46mm, with an average mean value of about 0.16 mm

Prototyping for Research and Industry

In this thesis we want to present some of the activities carried out during the PhD studies held at the PhD School "L. da Vinci" in the period from January 2012 to December 2014. The activities were held in the fields of robotics and mechanical engineering, and the main theme was the prototyping of new concepts, as well as the activity of conceptual design in its different phases, from generation of the idea, to the realization and testing of prototypes. The conceptual design phase is of fundamental importance to structure the process of generation of new ideas. Sometimes it is a process that is carried out unconsciously by the inventor. Providing a tool that allows to guide him in the various stages of idea generation can lead to advantages that let the inventor to explore areas from which take inspiration, which otherwise would not have been taken into account. An aspect of fundamental importance in the development of new prototypes is a process that goes in the opposite direction of the idea generation phase. Initially the conceptual design tends to provide tools to generate as many ideas as possible, but at some point there is the need to select a limited number of cases to investigate. Through the selection phase, which can be structured at levels more or less structured, and more or less qualitative/quantitative, the inventor tends to identify, case by case, which are the ideas in which is worth investing time and resources, before moving to the following stages. Prototyping, as well as its previous phase, now commonly called pretotyping, are mandatory steps for those who want to develop any new idea. The success of the final product or service may depend from the analysis of the pretotype first, and of the prototype later, since it allows to detect limits and possible improvements of the concept before moving to the final implementation phase

Digital Transformation in Healthcare

This book presents a collection of papers revealing the impact of advanced computation and instrumentation on healthcare. It highlights the increasing global trend driving innovation for a new era of multifunctional technologies for personalized digital healthcare. Moreover, it highlights that contemporary research on healthcare is performed on a multidisciplinary basis comprising computational engineering, biomedicine, biomedical engineering, electronic engineering, and automation engineering, among other areas

Revolutionising orthopaedic implants : a comprehensive review on metal 3D printing with materials, design strategies, manufacturing technologies, and post-process machining advancements

This paper conceptualises an understanding of advanced manufacturing methods to develop 3D-printed metallic orthopaedic implants, including a brief discussion on post-process machining. The significance of Metallic Additive Manufacturing (MAM) and its practicality for industrial applications is discussed through a juxtaposition with conventional casting and machining approach. Different alloys and suitable MAM techniques are thoroughly reviewed to determine optimum operating conditions. Although MAM can produce near-net shape parts, post-processing is an unavoidable requirement to improve surface quality and dimensional accuracy. A comparative study is presented, highlighting the importance of machining for post-processing in terms of cost savings and performance. Different materials are evaluated aiming to overcome problems associated with existing orthopaedic implants. The consequence of bone-implant mechanical mismatch leading to stress shielding and inadequate corrosion properties obstructing biodegradability are explored in detail. The effect of additive manufacturing parameters on mechanical, corrosion, and surface properties including biocompatibility is analysed. Evidence of MAM’s advantages over conventional manufacturing approaches, such as the use of functionally graded lattices and patient-specific customised designs, is also presented. Finally, for future studies, a two-way approach is conceptualised with material selection and manufacturing process control in progressions of implant development using MAM. Graphical Abstract

Revolutionising orthopaedic implants—a comprehensive review on metal 3D printing with materials, design strategies, manufacturing technologies, and post-process machining advancements

This paper conceptualises an understanding of advanced manufacturing methods to develop 3D-printed metallic orthopaedic implants, including a brief discussion on post-process machining. The significance of Metallic Additive Manufacturing (MAM) and its practicality for industrial applications is discussed through a juxtaposition with conventional casting and machining approach. Different alloys and suitable MAM techniques are thoroughly reviewed to determine optimum operating conditions. Although MAM can produce near-net shape parts, post-processing is an unavoidable requirement to improve surface quality and dimensional accuracy. A comparative study is presented, highlighting the importance of machining for post-processing in terms of cost savings and performance. Different materials are evaluated aiming to overcome problems associated with existing orthopaedic implants. The consequence of bone-implant mechanical mismatch leading to stress shielding and inadequate corrosion properties obstructing biodegradability are explored in detail. The effect of additive manufacturing parameters on mechanical, corrosion, and surface properties including biocompatibility is analysed. Evidence of MAM’s advantages over conventional manufacturing approaches, such as the use of functionally graded lattices and patient-specific customised designs, is also presented. Finally, for future studies, a two-way approach is conceptualised with material selection and manufacturing process control in progressions of implant development using MAM