• The korean journal of orthodontics
• /
• v.47 no.1
• /
• pp.21-30
• /
• 2017

Objective: The aim of this study was to investigate the three-dimensional (3D) position of the center of resistance of 4 mandibular anterior teeth, 6 mandibular anterior teeth, and the complete mandibular dentition by using 3D finite-element analysis. Methods: Finite-element models included the complete mandibular dentition, periodontal ligament, and alveolar bone. The crowns of teeth in each group were fixed with buccal and lingual arch wires and lingual splint wires to minimize individual tooth movement and to evenly disperse the forces onto the teeth. Each group of teeth was subdivided into 0.5-mm intervals horizontally and vertically, and a force of 200 g was applied on each group. The center of resistance was defined as the point where the applied force induced parallel movement. Results: The center of resistance of the 4 mandibular anterior teeth group was 13.0 mm apical and 6.0 mm posterior, that of the 6 mandibular anterior teeth group was 13.5 mm apical and 8.5 mm posterior, and that of the complete mandibular dentition group was 13.5 mm apical and 25.0 mm posterior to the incisal edge of the mandibular central incisors. Conclusions: Finite-element analysis was useful in determining the 3D position of the center of resistance of the 4 mandibular anterior teeth group, 6 mandibular anterior teeth group, and complete mandibular dentition group.

• The Journal of Korean Academy of Prosthodontics
• /
• v.49 no.3
• /
• pp.222-228
• /
• 2011

Purpose: The purposes of this study were to evaluate the stress distributions and the displacements of obturator for edentulous maxillectomy patients and to compare them with those of complete denture using three-dimensional finite element analysis. Materials and methods: Based on the CT image of edentulous patient, three-dimensional finite element model of edentulous maxillae was constructed. Three-dimensional finite element model of edentulous maxillae with palatal defect was also fabricated. On each model, complete denture and obturator prosthesis were created. Vertical static force of 200 N was applied on the left maxillary premolar and molar region. The von Mises stress values and the displacements of models were analyzed using three-dimensional finite element analysis. Results: Maximum von Mises stress values were recorded in the cortical bones of both models. The von Mises stress value in the complete denture model was 2.73 MPa and 2.69 MPa in the obturator model. High von Mises stress values were also observed on the tissue surface of prosthesis. The maximum value of the displacement in the obturator was higher than that of complete denture. Conclusion: The obturator showed a worse result in terms of stress distribution and displacement than complete denture. In the prosthodontic rehabilitation of edentulous maxillectomy patient accurate impression procedure based on patients'anatomy and application of prosthodontic principle should be considered.

• The Journal of the Korean dental association
• /
• v.55 no.1
• /
• pp.90-95
• /
• 2017

As residual ridge resorption occurs, complete dentures tend to become loose. Denture relining and rebasing are an essential element for improving a denture's stability and prevention side effect such as sore spot, epulis fissuratum. This paper focuses about health insurance is available for maintenance of complete denture and, methods of relining or rebasing.

• The Pure and Applied Mathematics
• /
• v.29 no.3
• /
• pp.207-230
• /
• 2022

In this article, we investigate several aspects of (R, S)-hyper bi-modules and describe some their properties. The concepts of fundamental relation, completes part and complete closure are studied regarding to (R, S)-hyper bi-modules. In particular, we show that any complete (R, S)-hyper bi-module has at least an identity and any element has an inverse. Finally, we obtain a few results related to the heart of (R, S)-hyper bi-modules.

• Korean Journal of Mathematics
• /
• v.25 no.4
• /
• pp.579-585
• /
• 2017

Based on injectivity, we introduce some definitions in the category NFHG of normal fuzzy hypergroups. And we show that a complete normal fuzzy hypergroup is a weakly injective object in NFHG. Also we investigate weak injectivity in the comma category NFHG/K.

• The Journal of Korean Academy of Prosthodontics
• /
• v.30 no.2
• /
• pp.286-318
• /
• 1992

The objective of preventive dentistry is the maintenance of a healthy dentition for the life of a patient. Unfortunately, if an individual has not received the benefit of a comprehensive program of preventive dentistry and has finally reached the edentulous state, as a consequence, he receives a set of complete denture. Dentures are mechanical devices and subject to the principles of mechanics. In some cases, the general health and nutritional status of the patient are felt to be the causative factors. But, the most important thing in residual ridge resorption is felt to be caused by the unequal distribution of functional forces. This study was to analyze mandibular stresses of complete denture occlusion by three dimensional finite element method. The results were as follows ; 1. As deformation and stress distribution of the complete denture of the mandible were concentrated on the upper lingual side of the mandible, alveolar ridge resorption of the mandible occurred from lingual side to labio-buccal side. 2. Analyzing by three dimensional F. E. M., the mandible is a very effective form for tolerating stress and deformation biomechanically. 3. According to the concentration of stress distibution in the upper buccal side of the lower posteriors, buccal shelf area must be a primary stress bearing area in the lower complete denture. 4. Lower complete denture moved horizontally to the balancing side under lateral occlusal force. 5. Bilateral balanced occlusion should be constructed in the complete denture for denture stability, especially in the protrusive movement. 6. Physical property of the denture base material was as important for stress distribution in the denture base as or even more than that in the mandible. 7. Impression technique is very important because of most of stress was concentrated between them due to close contact of the mandible and the denture base.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.331-334
• /
• 2004

In clinical use, coronary stents keep coronary arteries open after expansion with a balloon catheter and prevent the expanded artery from collapsing. Coronary stents are positioned in artery by catheter with a balloon along a guide wire to the lesion site. Flexibility is one of important ability for delivery. In this paper, Palmaz-Schatz stent and Tenax complete stent were selected because these are the most representative of tubular stents. Finite element analyses for the stent system were performed using ABAQUS/Standard code. The present study estimated the flexibility of coronary stents due to loading directions. Moreover the present paper suggests a numerical method to test the flexibility of stents. In conclusion this paper shows how the finite element analysis can be effectively organized in the stent development.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.6 no.4
• /
• pp.1000-1013
• /
• 2014

This paper presents some of the efforts by the authors towards numerical prediction of springing of ships. A time-domain Higher Order Boundary Element Method (HOBEM) based on cubic shape function is first presented to solve a complete second-order problem in terms of wave steepness and ship motions in a consistent manner. In order to avoid high order derivatives on the body surfaces, e.g. mj-terms, a new formulation of the Boundary Value Problem in a body-fixed coordinate system has been proposed instead of traditional formulation in inertial coordinate system. The local steady flow effects on the unsteady waves are taken into account. Double-body flow is used as the basis flow which is an appropriate approximation for ships with moderate forward speed. This numerical model was used to estimate the complete second order wave excitation of springing of a displacement ship at constant forward speeds.

• Advances in biomechanics and applications
• /
• v.1 no.1
• /
• pp.1-14
• /
• 2014

In this paper, a simple and accurate finite element model coupled to quasi-brittle damage law able to describe the multiple cracks initiation and their progressive propagation is developed in order to predict the complete force-displacement curve and the fracture pattern of human proximal femur under quasi-static load. The motivation of this work was to propose a simple and practical FE model with a good compromise between complexity and accuracy of the simulation considering a limited number of model parameters that can predict proximal femur fracture more accurately and physically than the fracture criteria based models. Different damage laws for cortical and trabecular bone are proposed based on experimental results to describe the inelastic damage accumulation under the excessive load. When the damage parameter reaches its critical value inside an element of the mesh, its stiffness matrix is set to zero leading to the redistribution of the stress state in the vicinity of the fractured zone (crack initiation). Once a crack is initiated, the propagation direction is simulated by the propagation of the broken elements of the mesh. To illustrate the potential of the proposed approach, the left femur of a male (age 61) previously investigated by Keyak and Falkinstein, 2003 (Model B: male, age 61) was simulated till complete fracture under one-legged stance quasi-static load. The proposed finite element model leads to more realistic and precise results concerning the shape of the force-displacement curve (yielding and fracturing) and the profile of the fractured edge.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.6
• /
• pp.583-588
• /
• 2015

Asymptotic method has been often used to theoretically analyze the complete contact problem. The error of the asymptotic results increases as the distance from the contact edge increases. The singularity cannot be properly obtained from a finite element (FE) analysis owing to the finiteness of the element size. In the present work, the complete contact problem in bonded condition is analyzed using a combined experimental-numerical approach to assist and/or compare with the asymptotic results. Al and Cu alloys are used for the material combination of the punch and substrate. 120 and 135 degrees are used for the punch angle. The FE models are validated by comparison of displacement distributions obtained by the FE analysis and $moir{\acute{e}}$ experiment. Generalized stress intensity factors are evaluated using the validated FE models. Stress field in the vicinity of the sharp contact edges obtained from the FE and asymptotic analyses are compared. The discrepancies are also discussed.