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The paper presents the reverse engineering process for a chain sprocket using 3D scanning technology. First, a detailed 3D scan using an Artec Space Spider 3D scanner is made in order to generate the digital model. Subsequently, based on this model, the 3D modelling process is performed using specialized modelling software such as Artec Studio, Geomagic Design X, and Autodesk Inventor to recreate the geometry and features of the part. A 3D printing technology based on an Ultimaker S5 Pro printer is used to obtain a physical prototype of the part. This technology provides a practical and efficient solution in the reconstruction process of complex objects. The reverse engineering method is useful in different areas such as engineering, manufacturing and repairs, facilitating the reproduction or complete of missing essentials components.

In this paper, a virtual model of the dental-maxillary device was obtained by scanning a skull taken from a corpse, and using a few sets of tomographic images. These images were processed with a program that allows the transformation of tomographic images into three-dimensional geometries based on gray shades. In an initial phase these geometries were in the form of discontinuous surfaces, which were then processed, finalized and transformed into virtual solids. Thus, in the SolidWorks program the dental-maxillary device was obtained as virtual solids. Such a Multi Body model has undergone kinematic simulations in the Motion model of SolidWorks, where the entire load system to which the analyzed model is subjected. At the end of the paper, important conclusions were highlighted.

In this paper we have detailed the CAD methods that led to the obtaining of vertebrae and intervertebral discs. Initially, all the vertebrae from a corpse were scanned three-dimensionally. These models have been taken over in the Geomagic program where replenishment, triangle reduction and finishing techniques have been applied. These surface models were imported into SolidWorks where they were transformed into virtual solids. In the Assembly module, all the virtual vertebrae were loaded where they were positioned anatomically. A system of vertebrae L4, L5 and intervertebral disc was analyzed in Ansys Workbench. Finally, important conclusions were drawn.

Serious pathological problems of the hip joint can be solved surgically, in some cases by joint prosthesis. For this reason, it is very important to be able to shape, in a first phase, the components of the prosthesis, which can then be tested virtually. For this purpose, the components of the prosthesis with fixation pins were firstly scanned three-dimensionally. This operation resulted in a model of a "cloud of points" which was subsequently transformed into virtual surfaces, then into virtual solids. These virtually solid components were assembled in a parameterized virtual environment. This prosthesis can be inserted into a biomechanical model of the hip joint and tested using the finite element method. At the end of the paper important conclusions were drawn.

Hip joint is one of the most complicated in the human body. It is complex due to the complicated geometry, but also to the biomechanics of this joint. Initially, three-dimensional scanning of a femur was attempted, but due to the fact that only the outer geometry could be obtained, this method was dropped. Computational methods have been used that based on identifying shades of gray on tomographic images and transposing them into geometries (surfaces). These surfaces processed with the Geomagic program were transformed into virtual solids in SolidWorks. In this program, bone components were assembled and pubic symphysis was modeled. Finally, the model was exported to Ansys where, based on normal walking loads, a finite element method simulation was performed. At the end of the paper interesting conclusions were highlighted.

Obesity, sedentarism, and other disadvantages of the modern age have led to the emergence of unknown pathological situations a few centuries before. At the same time, the development of medicine, orthopaedic surgery has led to finding ways to solve these situations. The present paper proves that the use of high-tech methods used in engineering can generate solutions in the field of orthopaedics both for obtaining new prothesis models, but also by creating virtual environments for tests. Several CAD techniques and techniques have been explored, coupled with medical imaging, can provide exciting solutions for obtaining virtual environments that can allow "in vitro" analysis of various normal, pathological or prosthetic joints. In this paper we have detailed how to obtain a prosthetic knee joint in a parameterized environment. This joint was tested virtually. In the final of the paper, main conclusions were made.

Implantology is based on the failure of orthopedic treatment, or cases where orthopedic treatment is incapable of reducing or maintaining, for example, fracture of the femoral neck with movement. The advantage of centromedular fixation is that it allows the bone to physically load as much as possible, minimizing the risk of implant failure. The drawbacks of conventional nails have been eliminated with the introduction of the centromedular stem locking system. The purpose of this study was to obtain several virtual biomechanical systems on which to study several types of tibial fractures and several osteosynthesis systems. Starting from the tomographic images of the tibia, a virtual model of this bone component was developed. This model was "finalized" and modified using certain Geomagic techniques and then imported into SolidWorks. The osteosynthesis element used was the rigid classical nail with orthopedic screws which was modeled using the direct observation and measurement method. It is intended that these virtual components to be used to make orthopedic virtual osteosynthesis systems that are then analyzed in Ansys with the finite element method.

The development of the finite element method (FEM) combined block polynomial interpolation with the concepts of finite difference formats and the variation principle. Because of this combination, the FEM overcomes the shortcomings of traditional variation methods while maintaining the benefits of current variation methods and the flexibility of the finite difference method. As a result, the FEM is an advancement above the traditional variation methods. The purpose of this study is to experimentally highlight the thermal behavior of two stomatognathic systems, one a control and the other presenting orthodontic treatment by means of a fixed metallic orthodontic appliance, both being subjected to several thermal regimes. In order to sustain this experimental research, we examined the case of a female subject, who was diagnosed with Angle class I malocclusion. The patient underwent a bimaxillary CBCT investigation before initiating the orthodontic treatment. A three-dimensional model with fully closed surfaces was obtained by using the InVesalius and Geomagic programs. Like the tissues examined in the patient, bracket and tube-type elements as well as orthodontic wires can be included to the virtual models. Once it is finished and geometrically accurate, the model is exported to an FEM-using program, such as Ansys Workbench. The intention was to study the behavior of two stomatognathic systems (with and without a fixed metallic orthodontic appliance) subjected to very hot food (70 °C) and very cold food (−18 °C). From the analysis of the obtained data, it was concluded that, following the simulations carried out in the presence of the fixed metallic orthodontic appliance, significantly higher temperatures were generated in the dental pulp.

The design of the access cavity is an important factor in endodontic treatment for the further evolution of the tooth. The objective of this study was to highlight the most favorable access cavity design (TrussAC, UltraAC, TradAC, CariesAC, ConsAC, RestoAC) based on the stress distribution on virtual models of mandibular molars. To achieve the objectives of the study, four series of virtual models of six molars were made. The first two series of external virtual models were obtained based on the three-dimensional scanning of the molars before the access cavity preparation and after their restoration, to obtain the density of the restorative materials. Internal morphology was added to the next two series of virtual models and after that, materials were added, specific for root canal obturation and coronal restoration. The simulations were performed for two coronary restoration materials, bulk fill composite and amalgam. The results showed, based on the stress maps, that the highest values were recorded for CariesAC and the lowest values for UltraAC. Comparing the two restorative materials, the lowest level of stress, strains, and displacements was highlighted in the case of UltraAC, TradAC, and ConsAC cavities for amalgam. The results obtained in this study should guide doctors towards a conservative attitude with the preservation of as much hard tissue as possible and the differentiated use of restorative materials according to the amount of tissue lost when preparing the access cavity.

CBCT (cone beam computed tomography) is an imaging investigation that provides three-dimensional (3D) images of craniofacial structures. The purpose of this study is to determine the mechanical behavior of an orthodontic system where the lingual treatment technique was used in a 25-year-old female patient from whom a set of CBCT scans was used. CBCT images were processed through software programs such as Invesalius, Geomagic, and Solid Works, to create models containing virtual solids. These models were then imported into Ansys Workbench 2019 R3 (a finite element method software program) for successive simulations to generate displacement maps, deformations, stress distributions, and diagrams. We observed that in the lingual technique, the lowest force occurring on the maxillary teeth is at 1.1, while the highest force appears at 2.3. In the mandible, the lowest force occurs at 4.6, and the highest force at 3.1. The values of the forces and the results of the finite element method can represent a basis for the innovation of new orthodontic springs and also of bracket elements. Thus, by using new technologies, orthodontic practice can be significantly improved for the benefit of patients. Other virtual methods and techniques can be used in future studies, including the application of virtual reality for orthodontic diagnosis.

The possibility of dental pulp damage during dental procedures is well known. According to studies, during finishing and polishing without cooling, temperatures of up to 140 °C or more can be generated. There are many studies that have analysed the influence of the finishing and polishing of fillings on the mechanical parameters, but the analysis of thermal parameters has led to uncertain results due to the difficulty of performing this in vivo. Background: We set out to conduct a study, using the finite element method, to determine the extent to which the type of class II cavity and the volume of the composite filling influence the duration of heat transfer to the pulp during finishing and polishing without cooling. Materials and Methods: A virtual model of an upper primary molar was used, with a caries process located on the distal aspect, in which four types of cavities were digitally prepared: direct access, horizontal slot, vertical slot and occlusal–proximal. All four cavity types were filled using a Filtek Supreme XT nanocomposite. Results: The study showed that the filling volume almost inversely proportionally influences the time at which the dental pulp reaches the critical temperature of irreversible damage. The lowest duration occurred in occlusal–distal restorations and the highest in direct access restorations. Conclusions: based on the results of the study, a working protocol can be issued so that finishing and polishing restorations without cooling are safe for pulpal health.

The restoration of class II cavities is predominantly carried out with composite materials. Due to the high failure rate in restoring this type of cavity, composite materials with much-improved properties and new application techniques have been promoted. The study aimed to analyze the mechanical behavior of several topical composite materials (nanocomposites, nanohybrids and ormocer) using different application techniques. In a lower second molar, a class II occlusal cavity was prepared. As filling materials, we used the following combinations: Admira Fusion and Admira Fusion Flow, Grandio and Grandio Flow, Filtek Supreme XT and Filtek Supreme Flow. These were applied using a snow plow, injection molded and Bichacho techniques. Three-dimensional scanning of the molar with the prepared cavity was performed, and then scanning of each layer of added composite material was performed, obtaining three-dimensional models. The virtual molar models were analyzed with software specific to the finite element analysis method, where their physical-mechanical properties were entered and assigned to the components of the virtual molar. Simulations at high forces specific to bruxism were then carried out and analyzed, and compared. The values of displacements and strain, for all six analyzed situations, are relatively small (range from 5.25 × 10−6–3.21 × 10−5 for displacement, 6.22 × 10−3–4.34 × 10−3 for strain), which validates all three methods and the materials used. As far as the stress values are concerned, they are similar for all methods (250–300 MPa), except for the snow plow and injection-molded techniques using Grandio and Grandio Flow composites, where the maximum von Mises stress value was more than double (approximately 700 MPa). When using the combination of Grandio and Grandio Flow materials, the 1 mm thickness of the fluid composite layer was found to have a major influence on occlusal forces damping as opposed to 0.5 mm. Therefore, the Bichacho technique is indicated at the expense of the snow plow and injection-molded techniques. The composite materials used by us in this study are state-of-the-art, with clear indications for restoring cavities resulting from the treatment of carious lesions. However, their association and application technique in the case of Class II cavities is of clinical importance for resistance to masticatory forces.

The success of endodontic treatment is dependent on the removal of bacteria. A modern strategy to reduce bacterial load is laser irradiation. During this procedure, there is a local increase in temperature with possible side effects. The aim of this study was to determine the thermal behavior of a maxillary first molar when performing the conventional irradiation technique using a diode laser. For this study, a 3D virtual model of a maxillary first molar was created. The preparation of the access cavity, the rotary instrumentation of the palatal root canal and the laser irradiation protocol were simulated. The model was exported in a finite element analysis program where the temperature and heat flux were studied. Temperature and heat flux maps were obtained, and the temperature increase on the internal wall of the root canal was analyzed. The maximum temperature value exceeded 400 °C and was maintained for less than 0.5 s. The obtained temperature maps support the bactericidal effect of diode laser and the limitation of damage to surrounding tissues. On internal root walls, the temperature reached several hundred degrees Celsius, but for very short durations. Conventional laser irradiation is an adjuvant method of decontamination of the endodontic system.

The finite element method (FEM) is a computational method that can solve all biomechanical problems, including the field of orthodontics. The purpose of this virtual experimental study is to determine the behavior of a real orthodontic system subjected to different systems of loads. To analyze the real orthodontic system, we studied the case of a 21-year-old female patient. We used the InVesalius program, which can transform a set of DICOM-type images taken from cone beam computed tomography (CBCT) into three-dimensional structures. These structures were edited, modified, completed, and analyzed from a geometric point of view with the help of the Geomagic software. The final result of these operations must be a three-dimensional model made up of perfectly closed surfaces so that they can be transformed into virtual solids. The model consisting of perfectly closed surfaces is loaded into computer-aided design (CAD) programs. Bracket and tube components, as well as orthodontic wires, can be added to these models, similar to the analyzed patient’s tissues. When the model is complete and geometrically correct, it is exported to a program that uses FEM, such as Ansys Workbench. The simulation was performed for the forces of 0.5, 0.6, 0.7, 0.8, 0.9, and 1 N. The intention was to determine the behavior of the entire orthodontic system for these force values. After running the simulations, result maps were obtained that were composed of displacement, strain, and stress diagrams. It was also found that, in addition to the known rigidity, the orthodontic system has some elasticity due to the orthodontic wires, as well as the periodontal ligaments. Thus, a virtual analysis study can be carried out starting from a real patient with pre-treatment CBCT images and the virtual models of the bracket and tube elements and of the orthodontic wires.

Cone beam computed tomography (CBCT) is a modern imaging technique that uses X-rays to investigate the structures of the dento-maxillary apparatus and obtain detailed images of those structures. The aim of this study was to determine a functional mathematical model able to evaluate the elastic force intensity on each bracket and tube type element and the ways in which those components act on the orthodontic system being used. To analyze a real orthodontic system, we studied the case of a 13-year-old female patient. To transfer geometric information from tomographic images, we used the InVesalius software. This software can generate three-dimensional reconstructions based on sequences and files in the DICOM format and was purchased from CBCT equipment. We analyzed and processed the geometries of the converted tissues in InVesalius using the Geomagic software. After using the Geomagic software, we exported the resulting model to the SolidWorks software used in computer-aided design. In this software, the model is transformed into a virtual solid. After making the geometric model, we analyzed the model using the Ansys Workbench software, which incorporates finite element analysis techniques. Following the simulations, we obtained result maps, which showed the complete mechanical behavior of the analyzed structures.

Aim of the study This study aimed to evaluate the resistance forces that develop in the dental structures of the two left upper premolars during mandibular movements, through dynamic simulation using the kinematic analysis and the finite elements method. Material and methods For this, using several softwares, we obtained a virtual model of the jaw that was attached to a virtual skull. For all the components of the skull and of the dento-maxilar apparatus mechanical properties were given. The movements as mandibule lifting, propulsion, retropulsion and laterality were simulated. Results The study highlighted the presence of resistance forces in the dental structures with values ​​between 31.781 N in the retropulsion movement and 174.104 N in the lateral movement. Conclusions These values ​​are close to the occlusive forces values in the conditions of a balanced occlusion.

The Proposition 4 from the 11-th volume (called Book of Lemmas) of „Great Books of the Western World” (printed in USA in 1952) presents the properties of a remarkable curve from Antiquity. This curve was studied by Archimedes, who called it Arbelos and it looks like a shoemaker's knife. It consists of 3 semicircles. The first part of the paper is dedicated to the description of an original mechanism, conceived to plot the above-mentioned curve. It is made of a rotating driving element and two dyads of RRR type. The curve plotted by the mechanism checks the equality of areas described by Archimedes. He proved (by using geometric reasonings) that the area of a circle whose diameter is equal to the height of the right triangle inscribed in the Arbelos curve’s big semicircle is equal to the Arbelos curve’s area. In the second part of the paper, the authors modified the mechanism’s parameters and obtained 3 particular cases of Arbelos curves. These particular curves, plotted with the modified mechanism, are also composed of 3 semicircles whilst exhibiting other equalities between areas. The authors used geometric reasonings to prove the equality between the area of each particular curve and the area of a circle whose diameter is equal to the leg of a right triangle inscribed in the big semicircle of the studied particular curve.

The paper presents some methods used to create and analyze human virtual bones. The cooperation between medical research team and the engineer research group give important tools for medical devices or implants design. To re-create anatomical 3D models it was used a CAD software which permits to define complex models. First, there were defined the "hard" parts as the main bone components and "soft" parts as ligaments or menisci using CT images. Also, using CAD methods, were created virtual models of human joints. In the last decade, a new concept called rapid prototyping, physical coating or without solid pre-form manufacturing, has become very popular.