scholarly journals Influence of Bone Quality on the Use of Implant Prostheses with Intermediate Pontic: Three-dimensional Finite Element Method

2021 ◽  
Author(s):  
Marcelo Bighetti Toniollo ◽  
Andrea Sayuri Silveira Dias Terada ◽  
Jair Pereira de Melo ◽  
Cláudio Rodrigues Rezende Costa ◽  
Diogo Henrique Vaz de Souza
Keyword(s):  
Cortical Bone ◽  
Bone Quality ◽  
Three Dimensional ◽  
Apical Region ◽  
Type I ◽  
Medullary Bone ◽  
Stress Concentrations ◽  
Type Iii ◽  
Physiological Limits ◽  
Three Dimensional Finite Element

Abstract Objective The present study aimed to observe the differences in the dissipation of the main minimum stresses with the use of a fixed pontic partial prosthesis supported by two regular length implants in cortical and medullary bone tissues of different qualities. Materials and Methods Experimental groups were as follows: QI (two regular length implants with fixed pontic partial prosthesis and bony qualities consistent with type I), QII (identical to QI, with bony qualities consistent with type II), and QIII (identical to QI, with bony qualities consistent with type III). All the groups were developed and analyzed in virtual simulation environment using AnsysWorkbench software. Results The results showed highest stress concentrations in the region of the turns of the implants, especially in the apical region surrounding the implants and most notably in those positioned in the posterior region, supporting the molars. In addition, comparing the cortical bone among the groups, the results revealed increasing levels of stress in the order of QI, QII, and QIII. Comparing the medullary bone among the groups, the results revealed increasing levels of stress in the order of QIII, QII, and QI. Conclusion It was concluded that greater stress disparity occurred in the comparison between groups QI and QIII. There was a higher TMiP in QI in the cortical bone, but considering the literature values, it would not pose risks to its physiological limits. The use of a pontic fixed partial prosthesis on two regular implants of type III bone quality may cause unfavorable physiological repercussions for the posterior implant apical medullary bone.

scholarly journals Effect of Age on Bone Structure Parameters in Laying Hens

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 570
Author(s):  
Masayoshi Yamada ◽  
Chongxiao Chen ◽  
Toshie Sugiyama ◽  
Woo Kyun Kim
Keyword(s):  
Cortical Bone ◽  
Bone Quality ◽  
Bone Mineral ◽  
Volume Fraction ◽  
Bone Structure ◽  
Bone Volume ◽  
Egg Laying ◽  
Medullary Bone ◽  
Mineral Density ◽  
Tibial Diaphysis

Changes in medullary and cortical bone structure with age remain unclear. Twenty Hy-Line W36 hens, 25 or 52 weeks of age, were euthanized, and both tibiae were collected when an egg was present in the magnum. Serial cross sections of the tibiae were stained with Alcian blue. The bones were scanned using micro-computed tomography. Trabecular width (Tb.Wi) was significantly higher (p < 0.05) in 25-week-old hens, whereas medullary bone tissue volume (TV) was significantly higher (p < 0.01) in 52-week-old hens. 25-week-old hens had significantly higher (p < 0.01) bone volume fraction (BVF = calcified tissue / TV). Moreover, the cortical bone parameters were significantly higher (TV and bone mineral content (BMC) at p < 0.05, and bone volume (BV) and BVF at p < 0.01) in younger hens. Open porosity and total porosity, which indicate less density, were significantly higher (p < 0.01) in older hens. Older hens showed significantly higher (p < 0.01) tibial diaphysis TV than younger hens. Younger hens had significantly higher (p < 0.01) BV, BVF and bone mineral density (BMD) of the tibial diaphysis. These findings reveal that reductions in medullary bone quality might be associated with age-related low estrogen levels and stimulation of osteoclastic bone resorption by parathyroid hormone. Cortical bone quality decreased with enlargement of the Haversian canals and loss of volume, with a longer egg-laying period leading to osteoporosis.

scholarly journals FEM analysis of a new miniplate: stress distribution on the plate, screws and the bone

2012 ◽  
Vol 06 (01) ◽  
pp. 009-015 ◽  
Author(s):  
Didem Nalbantgil ◽  
Murat Tozlu ◽  
Fulya Ozdemir ◽  
Mehmet Oguz Oztoprak ◽  
Tulin Arun
Keyword(s):  
Finite Element ◽  
Cortical Bone ◽  
Three Dimensional ◽  
Fem Analysis ◽  
Force Distribution ◽  
Bone Surface ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

ABSTRACTObjectives: Non-homogeneous force distribution along the miniplates and the screws is an unsolved question for skeletal anchorage in orthodontics. To overcome this issue, a miniplate structure was designed featuring spikes placed on the surface facing the cortical bone. The aim of this study was to examine and compare the force distribution of the newly designed plate-screw systems with the conventional one.Methods: A model of bone surface with 1.5 mm cortical thickness, along with the two newly designed miniplates and a standard miniplate-screw were simulated on the three-dimensional model. 200 g experimental force was applied to the tip of the miniplates and the consequential effects on the screws and cortical bone was evaluated using three-dimensional finite element method.Results: As a result of this finite element study, remarkably lower stresses were observed on the screws and the cortical bone around the screws with the newly designed miniplate when compared with the conventional one.Conclusion: The newly designed miniplate that has spikes was found effective in reducing the stress on and around the screws and the force was distributed more equivalently. (Eur J Dent 2012;6:9-15)

Wall Stresses Before and After Endovascular Repair of Abdominal Aortic Aneurysms

2004 ◽  
Author(s):  
Elena S. Di Martino ◽  
Ajay Bohra ◽  
Christine Scotti ◽  
Ender Finol ◽  
David A. Vorp
Keyword(s):  
Endovascular Aneurysm Repair ◽  
Three Dimensional ◽  
Invasive Procedure ◽  
Aortic Aneurysms ◽  
Aortic Tissue ◽  
Type I ◽  
Abdominal Aortic ◽  
Before And After ◽  
Anchoring System ◽  
Three Dimensional Finite Element

Endovascular aneurysm repair (EVAR) technique is a minimally invasive procedure approach to abdominal aortic aneurysm (AAA) repair. Following EVAR, isolated aortic tissue starts remodeling after the new blood path is established. The commercially available endovascular grafts (EVG) have been found to be prone to Type I endoleak, which is re-pressurization of the degenerated AAA sac following a breach in the seal mechanism of the EVG or migration due to failure of the mechanism holding the graft in place (Chuter, 2002) These inadequacies of EVGs might be attributed to the effect of non-optimal design of graft anchoring system. In the present study, we utilized pre-operative and post-operative computer tomography (CT) data with previously derived material properties to construct three-dimensional finite element (FE) models for AAA before and after the EVAR procedure. We studied the nature of stresses acting on the aorta before and after EVAR. In particular we investigated the physical forces acting on the EVG and how they are transferred to the aortic wall at graft anchoring sites.

scholarly journals A Comparative Three-Dimensional Finite Element Study of Two Space Regainers in the Mixed Dentition Stage

2020 ◽  
Vol 14 (01) ◽  
pp. 107-114
Author(s):  
Mohamed Ahmed Abdel Hakim ◽  
Nagwa Mohamed Ali Khatab ◽  
Kareem Maher Gaber Mohamed ◽  
Ahmad Abdel Hamid Elheeny
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
The Other ◽  
Mixed Dentition ◽  
Von Mises Stress ◽  
Stress Concentrations ◽  
Permanent Molar ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Abstract Objectives This study aims to compare the stress distribution and displacement that resulted from the use of a Gerber space regainer and sagittal distalizer using three-dimensional finite element analysis. Materials and Methods Three-dimensional simulated models of the appliances were developed using a software. The forces applied by the two appliances were 3N (tipping) and 15N (bodily), respectively. Displacement and von Mises stress on the compact and cancellous bone, periodontal ligament (PDL), crowns of the mandibular first, second permanent molars, and deciduous canines were calculated. Stress distribution and displacement values were measured via linear static analysis. Results Gerber space regainer showed greater displacement than that produced by the sagittal distalizer at the first permanent molar. However, such displacement was less at the other tested points when compared with that delivered by sagittal distalizer. The stresses created by Gerber appliance were higher in the crown and PDL of the deciduous canine than the crown of the first permanent molar crown. Conclusions Gerber appliance generates more distal force and less stress concentration on the crown of the mandibular first permanent molar than that created by the sagittal distalizer. On the other hand, stress concentrations produced by Gerber space regainer are found to be more on the crown and PDL of the deciduous canine. Therefore, it can be concluded that the use of Gerber appliance needs more anchorage.

Use of Sub-Modeling Techniques to Calculate Peak Stresses in Bolt Head-to-Shank Fillet Radius

2008 ◽  
Author(s):  
Richard E. Smith ◽  
Stephen J. Speicher
Keyword(s):  
Three Dimensional ◽  
Structural Response ◽  
Peak Stress ◽  
Finite Element Models ◽  
Stress Concentrations ◽  
Sufficient Detail ◽  
Structural Details ◽  
Modeling Techniques ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

There is an ever-increasing use of three-dimensional finite element models in the field of structural analysis to simulate structural response of complex geometries. Although these models are effective in simulating gross structural behavior, they are oftentimes not able to include sufficient detail to simulate small structural details where stress concentrations can occur. To overcome this limitation, sub-models can be used to calculate stresses in areas of peak stress. This paper discusses the process involved in calculating peak stresses in bolt head-to-shank interfaces using sub-modeling methods.

scholarly journals Study On The Application of Preoperative Three-Dimensional CT Angiography of Perigastric Arteries In Laparoscopic Radical Gastrectomy

2022 ◽  
Author(s):  
Peng Liu ◽  
Wenbin Yu ◽  
Meng Wei ◽  
Danping Sun ◽  
Xin Zhong ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Blood Loss ◽  
Three Dimensional ◽  
Classification Model ◽  
Type I ◽  
Radical Gastrectomy ◽  
Type Ii ◽  
Type Iii ◽  
Type Iv ◽  
Type V

Abstract Objection: To investigate the clinical value and significance of preoperative three-dimensional computerized tomography angiography (CTA) in laparoscopic radical gastrectomy for gastric cancer.Methods: The clinical data were analyzed retrospectively from 214 gastric cancer patients. We grouped according to whether to perform CTA. The gastric peripheral artery was classified according to CTA images of patients in the CTA group, and we compared and analyzed the difference of the data between the two groups.Results: The celiac trunk was classified according to Adachi classification: Type I (118/125, 94.4%),Type II (3/125, 2.4%),Type III (0/125, 0%),Type IV (1/125, 0.8%),Type V (2/125, 1.6%),Type VI (1/125, 0.8%).Hepatic artery classification was performed according to Hiatt classification standard:Type I (102/125, 81.6％),Type II (9/125, 7.2%),Type III (6/125, 4.8%),Type IV (2/125, 1.6%),Type V (3/125, 2.4%),Type VI (0, 0%),Others (3/125, 2.4%).And this study combined vascular anatomy and clinical surgical risk to establish a new splenic artery classification model. It was found that the operation time and estimated blood loss in the CTA group were significantly lower than those in the non-CTA group. In addition, the blood loss in the CTA group combined with ICG (Indocyanine Green) labeled fluorescence laparoscopy was significantly less than that in the group without ICG labeled. Conclusion: Preoperative CTA can objectively evaluate the vascular course and variation of patients, and then avoid the risk of operation, especially in combination with ICG labeled fluorescence laparoscopy, can further improve the quality of operation.

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