scholarly journals Evaluation of the auto surfacing methods to create a surface body of the mandible model

2022 ◽  
Vol 3 (1) ◽  
pp. 46-54
Author(s):  
Paweł Turek ◽  
Keyword(s):  
Surgical Procedure ◽  
Complex Geometry ◽  
Maxillofacial Surgery ◽  
Anatomical Structure ◽  
Cad Model ◽  
Triangle Mesh ◽  
Simple Task ◽  
Mesh Structure ◽  
Knowledge And Skills ◽  
Geomagic Software

Designing an anatomical structure for a surgical procedure is not a simple task. It is especially true of the craniofacial area, which consists of bone tissues with very complex geometry. CAD modelers need appropriate knowledge and skills in medicine and technical sciences to fully use the currently available tools in related processes with the reconstruction of the craniofacial areas. The presented preliminary studies are based on four patients treated at the Department of Maxillofacial Surgery. The segmentation process of the mandible model was performed in the ITK SNAP software. The process of generating surface body models was performed in the Auto Surfacing module in Geomagic software using two different methods: organic and mechanical. Then compare both methods for the accuracy of generating a CAD model of the mandible based on a triangle mesh structure in the Focus Inspection and the GOM Inspect software.

Design and Deformation of CAD Surface Models With Haptics

2004 ◽  
Author(s):  
X. Liu ◽  
G. Dodds ◽  
J. McCartney ◽  
B. K. Hinds
Keyword(s):  
Shape Control ◽  
Force Feedback ◽  
Complex Geometry ◽  
Virtual Space ◽  
Cad Model ◽  
Two Dimensional ◽  
Shape Functions ◽  
Ship Hulls ◽  
Control Functions ◽  
Surface Models

With traditional two-dimensional based interfaces, many CAD surface models, such as automobile bodies and ship hulls, are difficult to design and edit due to their 3D nature. This paper discusses the haptic-based deformation for the design of CAD surface models. With haptic devices (force feedback interfaces) designers can, in virtual space, touch a native B-rep CAD model, and use their tactile senses to manipulate it by pushing, pulling and dragging its surfaces in a natural 3D environment. The paper presents shape control functions. By using the shape functions, designers can directly manipulate and deform a selected region of a surface to the desired shape, and generate complex geometry with simple operations. Force feedback gives designers the greatest flexibility for the design of complex surfaces.

Automatic CAD Model Reconstruction from Multiple Point Clouds for Reverse Engineering

2002 ◽  
Vol 2 (3) ◽  
pp. 160-170 ◽  
Author(s):  
Jianbing Huang ◽  
Chia-Hsiang Menq
Keyword(s):  
Reverse Engineering ◽  
Boundary Surface ◽  
Point Clouds ◽  
Geometric Feature ◽  
Multiple Point ◽  
Reconstruction Method ◽  
Cad Model ◽  
Model Reconstruction ◽  
Triangle Mesh ◽  
Novel Technologies

In this paper, a systematic scheme is proposed and novel technologies are developed to automatically reconstruct a CAD model from a set of point clouds scanned from the boundary surface of an existing object. The proposed scheme is composed of three major steps. In the first step, multiple input point clouds are incrementally integrated into a watertight triangle mesh to recover the object shape. In the second step, mesh segmentation is applied to the triangle mesh to extract individual geometric feature surfaces. Finally, the manifold topology describing the connectivity information between different geometric surfaces is automatically extracted and the mathematical description of each geometric feature is computed. The computed topology and geometry information represented in ACIS modeling kernel form a CAD model that may be used for various downstream applications. Compared with prior work, the proposed approach has the unique advantage that the processes of recognizing geometric features and of reconstructing CAD models are fully automated. Integrated with state of the art scanning devices, the developed model reconstruction method can be used to support reverse engineering of high precision mechanical components. It has potential applications to many engineering problems with a major impact on rapid design and prototyping, shape analysis, and virtual reality.

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

Scanning ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Yueyi Tian ◽  
ChunXu Chen ◽  
Xiaotong Xu ◽  
Jiayin Wang ◽  
Xingyu Hou ◽  
...  
Keyword(s):  
3D Printing ◽  
Computer Aided Design ◽  
Fused Deposition Modeling ◽  
Complex Geometry ◽  
Maxillofacial Surgery ◽  
Three Dimensional ◽  
Oral And Maxillofacial Surgery ◽  
Affecting Factors ◽  
Fused Deposition ◽  
Oral Implantology

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.

scholarly journals Skull Thickness Calculation Using Thermal Analysis and Finite Elements

2021 ◽  
Vol 11 (21) ◽  
pp. 10483
Author(s):  
Mucahit Calisan ◽  
Muhammed Fatih Talu ◽  
Danil Yurievich Pimenov ◽  
Khaled Giasin
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Complex Geometry ◽  
Thermal Analyses ◽  
Human Head ◽  
Head Model ◽  
Skull Bone ◽  
Bone Thickness ◽  
Mesh Structure ◽  
Skull Model

In this study, the skull bone thicknesses of 150 patients ranging in age from 0 to 72 years were calculated using a novel approach (thermal analysis), and thickness changes were analyzed. Unlike conventional thickness calculation approaches (Beam Propagation, Hildebrand), a novel heat transfer-based approach was developed. Firstly, solid 3D objects with different thicknesses were modeled, and thermal analyses were performed on these models. To better understand the heat transfer of 3D object models, finite element models (FEM) of the human head have been reported in the literature. The FEM can more accurately model the complex geometry of a 3D human head model. Then, thermal analysis was performed on human skulls using the same methods. Thus, the skull bone thicknesses at different ages and in different genders from region to region were determined. The skull model was transferred to ANSYS, and it was meshed using different mapping parameters. The heat transfer results were determined by applying different heat values to the inner and outer surfaces of the skull mesh structure. Thus, the average thicknesses of skull regions belonging to a certain age group were obtained. With this developed method, it was observed that the temperature value applied to the skull was proportional to the thickness value. The average thickness of skull bones for men (frontal: 7.8 mm; parietal: 9.6 mm; occipital: 10.1 mm; temporal: 6 mm) and women (frontal: 8.6 mm; parietal: 10.1 mm; occipital: 10 mm; temporal: 6 mm) are given. The difference (10%) between men and women appears to be statistically significant only for frontal bone thickness. Thanks to the developed method, bone thickness information at any desired point on the skull can be obtained numerically. Therefore, the proposed method can be used to help pre-operative planning of surgical procedures.

Application of Modified Grid-Based Approach for Auto Mesh Generation of IT-Related Products

2006 ◽  
Vol 321-323 ◽  
pp. 12-15
Author(s):  
Young Jae Park ◽  
Byung Sun Kim ◽  
Han Ok Ko ◽  
Yoon Suk Chang ◽  
Jae Boong Choi ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Product Design ◽  
Mesh Generation ◽  
Industrial Application ◽  
Complex Geometry ◽  
Cellular Phone ◽  
Rough Boundary ◽  
Cad Model ◽  
Exact Geometry ◽  
Grid Based

A seamless analysis of IT-related products, such as cellular phone, LCD monitor and note PC etc., which are thin and complex geometry is one of great concerns in product design. However, there is a considerable amount of gap between the industrial application and fundamental academic studies due to a time consuming detailed mesh generation. In order to settle the bottleneck, an auto mesh generation program based on a modified grid-based approach is proposed in this paper. At first, base mesh and skin mesh were generated using informations on entities which extracted from an IGES (Initial Graphics Exchange Specification) file. Secondly, a provisional core mesh with a rough boundary geometry was constructed by superimposing the skin mesh into the base mesh generated from CAD model. And then, positions of boundary nodes were redistributed to delineate exact geometry of the provisional mesh. Finally, good qualified meshes were constructed by moving the positions of the nodes and splitting elements along boundary edges. In conclusion, it is anticipated that the developed program can be used as a promising pre-processor for static or dynamic analysis of various IT-related products.

Application of Grid-Based Approach for Auto Mesh Generation of Vacuum Chamber

2006 ◽  
Vol 306-308 ◽  
pp. 631-636 ◽  
Author(s):  
Young Jae Park ◽  
H.K. Kim ◽  
Yoon Suk Chang ◽  
Jae Boong Choi ◽  
Young Jin Kim
Keyword(s):  
Finite Element ◽  
Mesh Generation ◽  
Vacuum Chamber ◽  
Complex Geometry ◽  
Industrial Applications ◽  
Cad Model ◽  
Finite Element Analyses ◽  
Mesh Quality ◽  
Modeling Process ◽  
Grid Based

A seamless analysis of complex geometry is one of greatly interesting topic. However, there are still gaps between the industrial applications and fundamental academic studies owing to time consuming modeling process. To resolve this problem, an auto mesh generation program based on grid-based approach has been developed for IT-product in the present study. At first, base mesh and skin mesh are generated using the information of entities which extracted from IGES file. Secondly the provisional core mesh with rugged boundary geometry is constructed by superimposing the skin mesh as well as the base mesh generated from the CAD model. Finally, the positions of boundary nodes are adjusted to make a qualified mesh by adapting node modification and smoothing techniques. Also, for the sake of verification of mesh quality, the hexahedral auto mesh constructed by the program is compared with the corresponding tetrahedral free mesh and hexahedral mapped mesh through static finite element analyses. Thereby, it is anticipated that the grid-based approach can be used as a promising pre-processor for integrity evaluation of various IT-products.

Parameter Identification of Complex Structures Using Finite Element Model Updating Techniques

2015 ◽  
Author(s):  
Dimitrios Giagopoulos ◽  
Alexandros Arailopoulos
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Complex Geometry ◽  
Element Model ◽  
Mode Shapes ◽  
Cad Model ◽  
Modal Characteristics ◽  
Acceleration Time Histories ◽  
The Finite Element Model

In this work, an integrated reverse engineering strategy is presented that takes into account the complete process, from the developing of CAD model and the experimental modal analysis procedures to computational effective model updating techniques. Modal identification and structural model updating methods are applied, leading to develop high fidelity finite element model of geometrically complex and lightweight bicycle frame, using acceleration measurements. First, exploiting a 3D Laser Scanner, the digital shape of the real bike frame was developed and the final parametric CAD model was created. Next the finite element model of the frame was created by using quadrilateral shell and hexahedral solid elements. Due to complex geometry of the structure, the developed model consists of about one million degrees of freedom. The identification of modal characteristics of the frame is based on acceleration time histories, which are obtained through an experimental investigation of its dynamic response in a support-free state by imposing impulsive loading. A high modal density modal model is obtained. The modal characteristics are then used to update the finite element model. Single and multiobjective structural identification methods with appropriate substructuring methods, are used for estimating the parameters (material properties and shell thickness properties) of the finite element model, based on minimizing the deviations between the experimental and analytical modal characteristics (modal frequencies and mode shapes). Direct comparison of the numerical and experimental data verified the reliability and accuracy of the methodology applied.

scholarly journals IMPACT OF THE COVID-19 PANDEMIC ON SURGICAL PROCEDURES IN BRAZIL: A DESCRIPTIVE STUDY

2021 ◽  
Vol 23 (2) ◽  
pp. 139-148
Author(s):  
Bárbara Okabaiasse Luizeti ◽  
Victor Augusto Santos Perli ◽  
Gabriel Gonçalves da Costa ◽  
Igor da Conceição Eckert ◽  
Aluisio Marino Roma ◽  
...  
Keyword(s):  
Surgical Procedures ◽  
Surgical Procedure ◽  
Maxillofacial Surgery ◽  
Descriptive Study ◽  
Endocrine Gland ◽  
Primary Analysis ◽  
Upper Airways ◽  
Geographical Regions ◽  
The Mean ◽  
The Impact

COVID-19 pandemic has deeply affected medical practice, and conducts o minimize the overload of healthcare services were necessary. The objective of this study is to evaluate the impact of the pandemic in the practice of surgical procedures in Brazil. This is a descriptive study with data about hospitalizations for surgical procedures in Brazil from 2016 to 2020, collected from the Department of Informatics of Brazil’s Unified Health System (DATASUS). Primary analysis describes the variations in the number of elective, urgent and other types of surgical procedures performed during this period, by comparing the mean number of hospitalizations from 2016 to 2019 with the absolute number from 2020. Secondary analysis describe the variations in hospitalizations for surgical procedures during this period in each of Brazil’s geographical regions, and variations in different surgical procedure subgroups. There was a decrease of 14.88% [95% CI: 14,82-14,93] in hospitalizations for surgical procedures in 2020, when comparing to the mean between 2016-2019. Decrease rates were 34.82% [95% CI: 34,73-34,90] for elective procedures and 1.11% [95% CI: 1.07-1.13] for urgent procedures. Surgical procedure subgroups with highest decrease rates were endocrine gland surgery, breast surgery, oral-maxillofacial surgery and surgery of upper airways, face, head and neck. The overload of healthcare facilities demanded reductions in non-urgent activities to prevent services’ collapse. Further studies are needed to evaluate the social and clinical impact of such reductions and support the development of precise criteria defining which procedures should be prioritized.

Haptic-Assisted Virtual Osteotomy As a Training Tool

2017 ◽  
Author(s):  
Eder H. Govea-Valladares ◽  
Hugo I. Medellín-Castillo ◽  
Pedro J. García-Zugasti ◽  
Pablo A. Limon-Leyva
Keyword(s):  
Clinical Practice ◽  
Surgical Procedures ◽  
Surgical Procedure ◽  
Surgical Planning ◽  
Planning Process ◽  
Maxillofacial Surgery ◽  
Free Form ◽  
Virtual Training ◽  
Training Tool ◽  
Virtual Osteotomy

The maxillofacial surgery is a complex surgical procedure to correct facial malformations located in the head of the patient. A precise and reliable surgical planning is necessary for a successful maxillofacial surgical procedure. The experience and clinical practice of surgeons play a very important role during the surgical procedures. Modern Computer Aided Systems (CAS) have been developed in order to speed up the surgical planning process and to increase the accuracy and reliability of the surgical procedure. However, CAS systems have not been focused on their ability to train and to provide experience and clinical practice to novice surgeons or medical student. In this way CAS systems could be a potential tool to improve the skill of surgeons in order to decrease human errors in the maxillofacial treatment and surgical procedures. This paper presents an investigation to evaluate the use of virtual reality and haptic systems as a training tool for maxillofacial surgeries, in particular osteotomies procedures. The aim is to evaluate the effect of virtual training on surgeon skills. Thus, a virtual osteotomy system has been developed and is presented. The system is based on an open source computer and programming resources, and makes use of haptic technologies to provide the users with the sense of touch. The virtual osteotomy procedures implemented are based on current surgical orthognathic surgery procedures. Free-form 3D manual cutting of bone is available in the system by means of the haptic device and the force feedback provided to the user, which increases the level of realism of the virtual procedure. The evaluation results show that the haptic-enabled virtual training of osteotomies increases the psychomotor skills of the practitioner, leading to an improved accuracy when carrying out the actual bone cut.

A Matching Algorithm and Error Analysis on the Basis of Triangle Mesh

2011 ◽  
Vol 230-232 ◽  
pp. 968-972
Author(s):  
Li Min Zhu ◽  
Chun Guo Liu ◽  
Shao Hui Wang ◽  
Ming Zhe Li
Keyword(s):  
Work Piece ◽  
Cad Model ◽  
Shape Error ◽  
Triangle Mesh ◽  
Matching Method ◽  
Initial Value ◽  
Icp Algorithm ◽  
Matching Algorithm ◽  
Cloud Data ◽  
Fine Registration

In reverse engineering, in order to analyze the accuracy of formed work-piece, the shape error between the formed work-piece and its CAD model need to be calculated. In this paper, a matching method on the basis of triangle mesh is proposed. This matching method includes three parts: pre-positioning, rough registration and fine registration. Firstly, the maximum projective plane of cloud data is designed to parallel to the xy plane through translation and rotation, and cloud data is translated by a vector which can be obtained with the point with the maximum z coordinate and the origin of coordinates. Secondly, cloud data is gradually rotated 360 degree around z axis confirm the angle making the error minimum. In this way, an initial value of ICP algorithm can be obtained, which can avoid the local convergence in the algorithm. Finally, ICP algorithm can be applied to calculate the surface error further. After matching, the error between work-piece and the CAD model can be calculated by interpolation based on triangle mesh. The results show that the matching method can obtain the higher matching accuracy.

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