Endodontically treated teeth are known to have reduced structural strength. Periodontal ligament ... more Endodontically treated teeth are known to have reduced structural strength. Periodontal ligament (PDL) may influence fracture resistance. The purpose of this study was to assess the influence of including the PDL in biomechanical studies about endodontically treated and restored teeth. Forty human maxillary central incisors were treated endodontically and randomly divided into four groups: non-crowned (with and without an artificial ligament) and crowned (with and without an artificial ligament) with glass-ceramic crowns. All groups received prefabricated glass fiber posts and a composite resin core. Specimens were tested, under a flexural-compressive load, until failure occurred. The failure mode was registered for all specimens. The failure loads were recorded and analyzed using an ANOVA test (P<0.05). These results were compared with those predicted by a finite element model. The ANOVA did not show significant differences between the use of crown on the failure load (P=0.33...
Numerous research works have studied the effect of post-design parameters on the mechanical behav... more Numerous research works have studied the effect of post-design parameters on the mechanical behaviour of restored teeth without reaching any clear conclusions. Previous works by the authors ascertained the effect of material and post-dimensions for non-crowned restored teeth. The aim of this work was to study the effect of post-material and diameter for crowned teeth. First, an experimental fracture strength test was performed on eighteen extracted human maxillary central incisors. Teeth were decoronated, treated endodontically and restored (nine with glass fibre posts and nine with stainless steel posts). Several post-diameters were used. The final crown restoration was carried out using a reinforced glass-ceramic material. Failure loads were recorded and results were compared using the one-way anova. Secondly, the finite element technique was used to model the restored teeth and to compare the estimated stress distributions. The addition of the crown did not affect the strength of the restoration to any significant extent and post-diameter did not influence the biomechanical performance of either of the post-systems. The crown acts as a protector, thus eliminating the influence of the post-diameter that was found previously when using stainless steel posts, but it does not completely rule out the possibility of a root fracture. Significantly, lower failure loads were found experimentally for teeth restored with stainless steel posts. The stress distributions predicted by the model corroborated these findings and allowed the authors to propose the use of glass fibre posts as a more robust restorative technique.
Journal of Computational Design and Engineering, 2020
In this paper, we describe a voice-based interaction mechanism to annotate 3D models directly fro... more In this paper, we describe a voice-based interaction mechanism to annotate 3D models directly from a computer-aided design (CAD) modeling environment. The audio signal is captured and automatically transcribed to a textual 3D note, which is attached to the geometry and made available to other product information and business processes across the enterprise via a product data management system. Our approach provides a more natural and intuitive method to capture design and engineering knowledge that is particularly effective when large amounts of information need to be communicated. We discuss the rationale of the software architecture and the value of this modality for capturing knowledge in a collaborative engineering context. Finally, we examine the results of an experiment to validate our proposal. Our results show that 3D annotations are an effective mechanism to communicate design knowledge, which suggests the need for further developments in the areas of multimodal interaction...
International Journal of Engineering Education, 2017
In this paper, we build on the idea that specialized instruction improves the overall quality of ... more In this paper, we build on the idea that specialized instruction improves the overall quality of CAD documents by guidingstudents into selecting the most suitable modeling strategies and approaches. To this end, automatic assessment tools canbe used to detect errors and provide feedback, thus relieving instructors from routine checks and allowing them to addressquality errors and modeling aspects of higher semantic level. A representative commercial Model Quality Testing (MQT)solution was selected as a case study to determine whether these tools may become automated assistants for studentevaluation and feedback. As a result, a new taxonomy of modeling aspects that can be automatically checked is proposed.We claim that current MQT tools can supplement the learning of quality concepts, but require significant tuning and onlyprovide limited testing and tutoring capabilities. Extending the capabilities of these tools (through macros or dedicatedAPI’s), or even developing entirely new MQ...
Uno de los principales objetivos de la asignatura de Expresion Grafica en la Ingenieria es mejora... more Uno de los principales objetivos de la asignatura de Expresion Grafica en la Ingenieria es mejorar la capacidad de vision espacial del alumnado, ademas de transmitir conocimientos sobre tecnicas de representacion grafica, tanto por metodos tradicionales de geometria metrica como geometria descriptiva. En esta asignatura de primer ano, comun a diversos grados de ingenieria, resulta fundamental esta capacidad de vision espacial, ya que los alumnos necesitan interpretar desde diferentes sistemas de representacion bidimensional, el objeto real. Sin embargo, esto resulta dificil para muchos estudiantes, puesto que o bien no tienen formacion previa o bien dicha formacion tradicionalmente no ha incidido en ayudar al alumno en la reflexion e interpretacion. En consecuencia, se han venido produciendo un elevado numero de suspensos. Se considera que facilitar la interpretacion del objeto implicara una mejora educativa significativa. Este trabajo presenta la implementacion y los resultados de ...
In the history-based, feature-based, parametric CAD approach, 2D profile sketches are the basis f... more In the history-based, feature-based, parametric CAD approach, 2D profile sketches are the basis for 3D models. Fully-constraining profiles is mandatory to create robust profiles. At present, neither CAD applications nor Model Quality Testing Tools usually check whether 2D profiles contain redundant constraints. Besides, our experience shows that novices tend to introduce redundant constraints. We hypothesize that 2D profiles over-constrained with redundant relations are more difficult to edit than those that avoid redundancies. In the present work―and as a first step to demonstrate this hypothesis―an experiment was conducted. Students of the subject “Graphics engineering” were taught on the creation of constrained 2D profiles. Then, they were asked two questions. On the one hand, novices had to identify and reason whether a simple given profile was fully-constrained, over-constrained or under-constrained. On the other hand, they had to identify and point out the types of the constra...
One of the main objectives of Engineering Graphics’ syllabus is to improve the capacity of spatia... more One of the main objectives of Engineering Graphics’ syllabus is to improve the capacity of spatial vision of students, as well as providing essential teaching of graphic representation techniques. In this course, students should create and interpret engineering drawings. However, a significant number of them have problems interpreting and understanding multiview orthographic projections. The course is commonly studied at first year of several engineering Bachelor’s Degrees. In this course, the capacity of spatial vision is critical, as students have to interpret a real object from different projection methods. Nevertheless, this is not an obvious task for most students, since either they have no prior training or traditionally this training has no effect on student’s capability of reflexion and interpretation. We consider that facilitating the object interpretation may involve a significant educational improvement. For this reason, in this work we present the approach and developmen...
Endodontically treated teeth are known to have reduced structural strength. Periodontal ligament ... more Endodontically treated teeth are known to have reduced structural strength. Periodontal ligament (PDL) may influence fracture resistance. The purpose of this study was to assess the influence of including the PDL in biomechanical studies about endodontically treated and restored teeth. Forty human maxillary central incisors were treated endodontically and randomly divided into four groups: non-crowned (with and without an artificial ligament) and crowned (with and without an artificial ligament) with glass-ceramic crowns. All groups received prefabricated glass fiber posts and a composite resin core. Specimens were tested, under a flexural-compressive load, until failure occurred. The failure mode was registered for all specimens. The failure loads were recorded and analyzed using an ANOVA test (P<0.05). These results were compared with those predicted by a finite element model. The ANOVA did not show significant differences between the use of crown on the failure load (P=0.33...
Numerous research works have studied the effect of post-design parameters on the mechanical behav... more Numerous research works have studied the effect of post-design parameters on the mechanical behaviour of restored teeth without reaching any clear conclusions. Previous works by the authors ascertained the effect of material and post-dimensions for non-crowned restored teeth. The aim of this work was to study the effect of post-material and diameter for crowned teeth. First, an experimental fracture strength test was performed on eighteen extracted human maxillary central incisors. Teeth were decoronated, treated endodontically and restored (nine with glass fibre posts and nine with stainless steel posts). Several post-diameters were used. The final crown restoration was carried out using a reinforced glass-ceramic material. Failure loads were recorded and results were compared using the one-way anova. Secondly, the finite element technique was used to model the restored teeth and to compare the estimated stress distributions. The addition of the crown did not affect the strength of the restoration to any significant extent and post-diameter did not influence the biomechanical performance of either of the post-systems. The crown acts as a protector, thus eliminating the influence of the post-diameter that was found previously when using stainless steel posts, but it does not completely rule out the possibility of a root fracture. Significantly, lower failure loads were found experimentally for teeth restored with stainless steel posts. The stress distributions predicted by the model corroborated these findings and allowed the authors to propose the use of glass fibre posts as a more robust restorative technique.
Journal of Computational Design and Engineering, 2020
In this paper, we describe a voice-based interaction mechanism to annotate 3D models directly fro... more In this paper, we describe a voice-based interaction mechanism to annotate 3D models directly from a computer-aided design (CAD) modeling environment. The audio signal is captured and automatically transcribed to a textual 3D note, which is attached to the geometry and made available to other product information and business processes across the enterprise via a product data management system. Our approach provides a more natural and intuitive method to capture design and engineering knowledge that is particularly effective when large amounts of information need to be communicated. We discuss the rationale of the software architecture and the value of this modality for capturing knowledge in a collaborative engineering context. Finally, we examine the results of an experiment to validate our proposal. Our results show that 3D annotations are an effective mechanism to communicate design knowledge, which suggests the need for further developments in the areas of multimodal interaction...
International Journal of Engineering Education, 2017
In this paper, we build on the idea that specialized instruction improves the overall quality of ... more In this paper, we build on the idea that specialized instruction improves the overall quality of CAD documents by guidingstudents into selecting the most suitable modeling strategies and approaches. To this end, automatic assessment tools canbe used to detect errors and provide feedback, thus relieving instructors from routine checks and allowing them to addressquality errors and modeling aspects of higher semantic level. A representative commercial Model Quality Testing (MQT)solution was selected as a case study to determine whether these tools may become automated assistants for studentevaluation and feedback. As a result, a new taxonomy of modeling aspects that can be automatically checked is proposed.We claim that current MQT tools can supplement the learning of quality concepts, but require significant tuning and onlyprovide limited testing and tutoring capabilities. Extending the capabilities of these tools (through macros or dedicatedAPI’s), or even developing entirely new MQ...
Uno de los principales objetivos de la asignatura de Expresion Grafica en la Ingenieria es mejora... more Uno de los principales objetivos de la asignatura de Expresion Grafica en la Ingenieria es mejorar la capacidad de vision espacial del alumnado, ademas de transmitir conocimientos sobre tecnicas de representacion grafica, tanto por metodos tradicionales de geometria metrica como geometria descriptiva. En esta asignatura de primer ano, comun a diversos grados de ingenieria, resulta fundamental esta capacidad de vision espacial, ya que los alumnos necesitan interpretar desde diferentes sistemas de representacion bidimensional, el objeto real. Sin embargo, esto resulta dificil para muchos estudiantes, puesto que o bien no tienen formacion previa o bien dicha formacion tradicionalmente no ha incidido en ayudar al alumno en la reflexion e interpretacion. En consecuencia, se han venido produciendo un elevado numero de suspensos. Se considera que facilitar la interpretacion del objeto implicara una mejora educativa significativa. Este trabajo presenta la implementacion y los resultados de ...
In the history-based, feature-based, parametric CAD approach, 2D profile sketches are the basis f... more In the history-based, feature-based, parametric CAD approach, 2D profile sketches are the basis for 3D models. Fully-constraining profiles is mandatory to create robust profiles. At present, neither CAD applications nor Model Quality Testing Tools usually check whether 2D profiles contain redundant constraints. Besides, our experience shows that novices tend to introduce redundant constraints. We hypothesize that 2D profiles over-constrained with redundant relations are more difficult to edit than those that avoid redundancies. In the present work―and as a first step to demonstrate this hypothesis―an experiment was conducted. Students of the subject “Graphics engineering” were taught on the creation of constrained 2D profiles. Then, they were asked two questions. On the one hand, novices had to identify and reason whether a simple given profile was fully-constrained, over-constrained or under-constrained. On the other hand, they had to identify and point out the types of the constra...
One of the main objectives of Engineering Graphics’ syllabus is to improve the capacity of spatia... more One of the main objectives of Engineering Graphics’ syllabus is to improve the capacity of spatial vision of students, as well as providing essential teaching of graphic representation techniques. In this course, students should create and interpret engineering drawings. However, a significant number of them have problems interpreting and understanding multiview orthographic projections. The course is commonly studied at first year of several engineering Bachelor’s Degrees. In this course, the capacity of spatial vision is critical, as students have to interpret a real object from different projection methods. Nevertheless, this is not an obvious task for most students, since either they have no prior training or traditionally this training has no effect on student’s capability of reflexion and interpretation. We consider that facilitating the object interpretation may involve a significant educational improvement. For this reason, in this work we present the approach and developmen...
Uploads