scholarly journals Stress analysis of a single prosthesis on a poorly positioned implant

2021 ◽  
Vol 10 (11) ◽  
pp. e579101119815
Author(s):  
Francisco Carlos dos Santos Reis ◽  
William Cunha Brandt ◽  
Letícia Cristina Cidreira Boaro ◽  
Milton Edson Miranda
Keyword(s):  
Shear Stress ◽  
Cortical Bone ◽  
Cervical Region ◽  
Control Group ◽  
Medullary Bone ◽  
Compressive Stresses ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Single Implant ◽  
Experimental Group

The mechanical positioning behavior of a mal-positioned implant was evaluated in the finite element method. Models were created in SolidWorks Professional 2013® software with a single implant rehabilitation. The following were analyzed: Control Group, crown aligned to the implant long axis; Experimental Group, crown shifted 3 mm mesial proximally to the implant axis. Compressive stresses in cortical and medullary bone, and Von Mises stresses in implants and components were evaluated. With 100 N occlusal loading at 5 points. The peak von Mises stresses in the prosthetic screw of the experimental group (138.45 MPa) were 43.60% higher compared to the control group (96.41 MPa). The stresses in the prosthetic pillar were localized in the abutment region and the experimental group showed (875.63 MPa), 28% higher than the control group (683.88 MPa). Regarding the implant, the maximum stress peaks were located in the implant platform and the experimental group showed stress values of (1081.4) MPa and was 26.42% higher than the control 855.39 MPa. The cortical bone tissue of the experimental group showed shear stress values 10.81% higher than the control. The stress values were 151.36 MPa for the experimental group and (136.59 Mpa) for the control. The medullary bone showed shear stress (8.31 MPa) and was 12.29% higher than the control (7.40 MPa). A maximum peak was obtained in the cervical region of the medullary bone, adjacent to the cortical bone. The experimental group with a mal-positioned implant showed the highest maximum stresses for all simulated prosthetic components.

COMPARATIVE STRESS ANALYSIS OF LINGUALIZED AND CONVENTIONAL BALANCED OCCLUSION SCHEMES IN A FULL-ARCH FIXED IMPLANT PROSTHESIS USING FINITE ELEMENT ANALYSIS

2017 ◽  
Vol 17 (04) ◽  
pp. 1750074
Author(s):  
MD ABU HASAN ◽  
PANOS S. SHIAKOLAS
Keyword(s):  
Cortical Bone ◽  
Acrylic Resin ◽  
Element Analysis ◽  
Posterior Teeth ◽  
Failure Index ◽  
Biomechanical Behavior ◽  
Denture Teeth ◽  
Implant Prosthesis ◽  
Von Mises ◽  
Von Mises Stresses

This study compares the biomechanical behavior of a mandibular full-arch fixed implant prosthesis with four implants under lingualized and conventional balanced occlusion schemes. The acrylic resin denture was supported by four titanium cylindrical implants and connected via a titanium prosthetic rectangular bar. Orthotropic material was used for the cortical and cancellous bones. The applied loadings were vertical and bilateral: 100[Formula: see text]N on first molar and 50[Formula: see text]N on first and second premolars each. For the lingualized balanced occlusion, the loadings were applied in central fossae of the posterior teeth, whereas for the conventional balanced occlusion the loadings were applied in central fossae and buccal cusps. The maximum von-Mises stresses for the lingualized and conventional balanced schemes were 301[Formula: see text]MPa and 25[Formula: see text]MPa, respectively, and were located at the neck of the posterior implants. In the denture teeth, the highest stress was located at the beginning of the cantilever extension. In the cortical bone, according to Tsai–Wu criterion, the failure index for the lingualized balanced occlusion was 1.10 and for the conventional balanced occlusion was 0.83. Thus, the conventional balanced occlusion demonstrated more favorable stress distribution in the implants and the cortical bone than the lingualized balanced occlusion.

Analysis of Loads and Stresses for a Sewing Needle

2002 ◽  
Author(s):  
Yuan Mao Huang
Keyword(s):  
Shear Stress ◽  
Personal Computer ◽  
Failure Modes ◽  
Von Mises Stress ◽  
Bending Stress ◽  
Principal Stresses ◽  
Acceptable Accuracy ◽  
Von Mises ◽  
Von Mises Stresses ◽  
The Cost

This study analyzes the loads of a needle by using singularity functions and determines the Von-Mises stresses to predict the failure modes of needles by using a personal computer. After principal stresses are calculated from the bending stress, compressive stress and shear stress, predicted failure modes of needles based on the Von-Mises stress coincide with practical existing failure modes reported by a manufacturer. These calculated stresses are also compared with the results obtained by using the software ABAQUS in the mainframe, and the deviation between the results calculated by these two methods is also investigated. Using this methodology can obtain loads, stresses and failure modes of a needle with acceptable accuracy while reducing the cost of using the commercial software in the mainframe.

scholarly journals Stress distribution in a mandibular premolar after separated nickel-titanium instrument removal and root canal preparation: a three-dimensional finite element analysis

2019 ◽  
Vol 47 (4) ◽  
pp. 1555-1564 ◽  
Author(s):  
Na Ni ◽  
Jing Ye ◽  
Liyuan Wang ◽  
Simin Shen ◽  
Lei Han ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Cervical Region ◽  
Element Analysis ◽  
Straight Line ◽  
Mandibular First Premolar ◽  
Von Mises ◽  
Von Mises Stresses

Objective This study used finite element analysis (FEA) to assess the von Mises stresses of a mandibular first premolar after removing a separated instrument with an ultrasonic technique. Methods FEA models of the original and treated mandibular first premolar were reconstructed, and three models (the original canal, size 30/taper 0.04 canal, and separated instrument removal canal) were created. Two-direction (vertical and lateral) loading patterns were simulated with a 175-N force. The maximum von Mises stresses of the models within the roots from the apex to the cervical region were collected and summarized. Results Under vertical and lateral loads, all maximal values in the three models were localized in the straight-line access region. Compared with the original model (model 1), the treated models (models 2 and 3) had greater maximum stress values from the apex to the cervical region. Greater differences in the maximum von Mises stresses between models 2 and 3 were present in the straight-line access region. Conclusions Separated instrument removal caused changes in stress distribution and increases in stress concentration in the straight-line access region of roots.

scholarly journals Comparison of Orthodontic Root Resorption of Root-filled and Vital Teeth Using Micro–computed Tomography

2019 ◽  
Vol 90 (1) ◽  
pp. 56-62 ◽  
Author(s):  
Kadir Kolcuoğlu ◽  
Aslihan Zeynep Oz
Keyword(s):  
Computed Tomography ◽  
Tooth Extraction ◽  
Root Resorption ◽  
Cervical Region ◽  
Control Group ◽  
Micro Computed Tomography ◽  
Mean Values ◽  
The Mean ◽  
The Difference ◽  
Experimental Group

ABSTRACT Objective To evaluate the difference in orthodontic root resorption between root-filled and vital teeth. Material and Methods Sixteen individuals who required bilateral premolar tooth extraction due to orthodontic treatment and had a previously root-filled premolar tooth on one side were included in the study. The experimental group consisted of root-filled premolar teeth, and the control group consisted of contralateral vital premolar teeth. A 150-g buccally directed force was applied to these teeth using 0.017 × 0.025-inch TMA cantilever springs. The premolars were extracted 8 weeks after the application of force. Images were obtained using micro–computed tomography. Resorption measurements were obtained using the Image J program. Results The mean values for resorption were 0.08869 mm3 for the root-filled teeth and 0.14077 mm3 for the contralateral teeth, indicating significantly less resorption for the root-filled teeth compared with the contralateral teeth after the application of orthodontic force (P = .003). In both groups, the most resorption was seen on the cervical-buccal and apical-lingual surfaces. The mean resorption value of the cervical region was 0.06305 mm3 in the control group and 0.0291 mm3 in the experimental group, and the difference was statistically significant (P = .002). Conclusions Root-filled teeth showed significantly less orthodontic root resorption than vital teeth.

scholarly journals The sensitivity of contact stresses in the mandibular premolar region to the shape of Zirconia dental implant: A 3D finite element study

2018 ◽  
Vol 24 (2) ◽  
pp. 55-63 ◽  
Author(s):  
Duraisamy Velmurugan ◽  
Masilamany Santha Alphin ◽  
Benedict Jain AR Tony
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Cortical Bone ◽  
Transition Region ◽  
Dental Implant ◽  
Cancellous Bone ◽  
Contact Stresses ◽  
Thread Profile ◽  
Von Mises ◽  
Von Mises Stresses

Abstract Background: Implant thread profile plays a vital role in magnitude and distribution of contact stresses at the implant-bone interface. The main goal of this study was to evaluate the biomechanical effects of four distinct thread profiles of a dental implant in the mandibular premolar region. Methods: The dental implant represented the biocompatible Zirconia material and the bone block was modelled as transversely isotropic and elastic material. Three-dimensional finite element simulations were conducted for four distinct thread profiles of a dental implant at 50%, 75%, and 100% osseointegration. An axial static load of 500 N was applied on the abutment surface to estimate the stresses acting within the bones surrounding the implant. Results: Regions of stress concentration were seen mostly along the mesiodistal direction compared to that in the buccolingual direction. The cortical bone close to the cervical region of the implant and the cortical bone next to the first thread of the implant experienced peak stress concentration. Increasing the degree of osseointegration resulted in increased von-Mises stresses on the implant-cortical transition region, the implant-cancellous transition region, the cortical bone, and the cancellous bone. Conclusion: The results show that the application of distinct thread profiles at different degrees of osseointegration had significant effect on the stresses distribution contours in the surrounding bony structure. Comparing all four thread profiles, a dental implant with V-thread profile induced lower values of von-Mises stresses and shear stresses on the implant-cortical transition region, implant-cancellous transition region, cortical bone, and cancellous bone.

scholarly journals Evaluation of the stress generation on the cortical bone and the palatal micro-implant complex during the implant-supported en masse retraction in lingual orthodontic technique using the FEM: Original research

2019 ◽  
Vol 13 (3) ◽  
pp. 192-199 ◽  
Author(s):  
Tarulatha Revanappa Shyagali ◽  
Dhaval Aghera
Keyword(s):  
Cortical Bone ◽  
Element Model ◽  
Stress Generation ◽  
Original Research ◽  
Final Model ◽  
Set Up ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Micro Implants ◽  
Retraction Force

Background. This study aimed to evaluate and analyze the distribution of stresses on the palatal micro-implants and the cortical bone at the micro-implant site with optimal orthodontic retraction force in lingual orthodontics. Methods. ANSYS 12.1 software was used to construct the finite element model of the maxillary bone, teeth and the periodontal ligament along with the lingual bracket set-up with wire and the micro-implant. Six- and 8-mm micro-implants were constructed. The final model consisted of 99190 nodes and 324364 elements. A 200-gram of retraction force was applied from the micro-implant to the anterior retraction hook. The micro-implant was embedded between the second premolar and the first molar. Hyper-view software was used to get the results in X-Y-Z dimensions. Results. The maximum von Mises stresses detected were 52.543 MPa for 6-mm micro-implant and 54.489 MPa for 8-mm micro-implant. Maximum stress was at the neck of the micro-implant. The 8-mm implant model showed 6×10-3 mm of lingual displacement. The least displacement of 1×10-3 mm was noticed for both the implant models in the apico-occlusal direction. The maximum von Mises stresses in the cortical bone at the micro-implant site was 18.875 MPa for 6-mm micro-implant and 21.551 MPa for 8-mm micro-implant. Conclusion. Six-mm micro-implant can be the choice for the implant-supported lingual orthodontic retraction as it produced minimal stresses on the cortical bone, and the initial stress displacements produced on the micro-implant were also minimal.

scholarly journals Impact of Pilates on the Intensity of Pain in the Spine of Women of the First Mature age

2020 ◽  
Vol 20 (1) ◽  
pp. 12-17
Author(s):  
Vitalii Kashuba ◽  
Yuliia Tomilina ◽  
Nataliia Byshevets ◽  
Inna Khrypko ◽  
Olha Stepanenko ◽  
...  
Keyword(s):  
Lumbar Spine ◽  
Visual Analogue Scale ◽  
Analogue Scale ◽  
Cervical Region ◽  
Control Group ◽  
Sports Club ◽  
Significant Difference ◽  
Thoracic And Lumbar Spine ◽  
Experimental Group ◽  
Different Parts

The purpose of the study is to determine the dynamics of pain intensity in different parts of the spine in women of the first mature age under the influence of pilates. Materials and methods. 64 women took part in research. The women were divided into two groups, each of which included 32 people. The study was carried out at the Sokol sports club and the Olimp fitness club in Kiev. We used the questionnaire “Visual analogue scale of pain”.  Results. We measured the level of pain in the cervical, thoracic and lumbar spine of women of the first mature age. It was found that only 4.69 % of women do not have pain. It was found that women of the first mature age the most often feel painin the cervical region. The women of the control group were engaged in a typical Pilates program. The women of the experimental group were engaged in the author’s program, a feature of which was the use of large equipment during classes. In addition, women who could not attend classes were offered the Pilates computer program. For the experiment, no statistically significant difference between the level of pain in different parts of the spine of women was established. After the experiment, a statistically significant decrease in the level of pain in the lumbar section of women in the experimental group was recorded compared with women in the control group.  Conclusions. The results indicate the effectiveness of large equipment to reduce the level of pain in the back of a woman.

scholarly journals Acute and chronic effect of stretching exercise on posture and flexibility of nurses and licensed practical nurses

2020 ◽  
pp. 1-6 ◽  
Author(s):  
José Nunes da Silva Filho ◽  
Jonas Lírio Gurgel ◽  
Elirez Bezerra da Silva ◽  
Flávia Porto
Keyword(s):  
Exercise Program ◽  
Body Posture ◽  
Cervical Region ◽  
Exercise Session ◽  
Control Group ◽  
Lumbar Region ◽  
Anthropometric Measures ◽  
Licensed Practical Nurses ◽  
Practical Nurses ◽  
Experimental Group

Introduction: nurses and licensed practical nurses are among the most affected by postural deviations and their drawbacks, in the world. One of the ways to mitigate these ills is physical exercise, and it can be done at work environment, however, not as a form of workout gymnastics. Objective: To verify the effects of a muscle stretching exercise program (MSE) on posture and flexibility of nurses. Methods: Controlled clinical experiment with 28 nurses, aged 18-60 years, divided into experimental group (n=15) and control group (n=13). Anthropometric measures, flexibility and body posture of the trunk were performed. The intervention was of 08 weeks of MSE; each session lasted 40 min. The exercises had four sets of 30s of tension for 30s of the interval. An independent t-test compared the characteristics of the samples. The chi-square test treated the results regarding body posture, and the level of significance was p ≤ 0.05. Results: MSE promoted positive and chronic positive changes in the Experimental Group with attenuation of the concavities of the vertebral column in the cervical and thoracic regions. In the alignment of the cervical region and the curvature of the lumbar region, the effects were observed after the eight weeks of training, including sharp reduction of gibbosity in the scapula region after the exercise session. Conclusion: MSE promoted acute and chronic positive changes in body posture and flexibility in nurses.

scholarly journals The Effect of Hypercholesterolemia on Cortical Bone Thickness of Wistar Rats (Rattus norvegicus)

2021 ◽  
Vol 55 (1) ◽  
pp. 63
Author(s):  
Auliya Dzaqiyatus Sofka ◽  
Pudji Lestari ◽  
Gadis Meinar Sari
Keyword(s):  
Cortical Bone ◽  
Rattus Norvegicus ◽  
Wistar Rats ◽  
Protective Factor ◽  
Control Group ◽  
Standard Diet ◽  
Bone Thickness ◽  
Cortical Bone Thickness ◽  
Osteoblast Activity ◽  
Experimental Group

There have been several studies reporting the effect of hypercholesterolemia on cortical thickness, but it remains a controversy. Some studies suggest that hypercholesterolemia can decrease osteoblast activity and increase osteoclast activity. Meanwhile other studies suggest that hypercholesterolemia is a protective factor of osteoporosis. Therefore, it is necessary to conduct a study to determine the effect of hypercholesterolemia on cortical bone thickness. Method: This study used 8 rats (Rattus norvegicus) that were divided into 2 groups, including control group (K0) that was given standard diet and experimental group (K1) that was given high fat diet for 28 days and all were executed to obtain the femur bone. The cortical bone thickness was measured by using Optilab Viewer and Optilab Image Raster software. Result: The data analysis was conducted using independent t-test. A p value of <0.05 is considered significant. The results showed that hypercholesterolemia had significant effect on cortical bone thickness. The average cortical bone thickness in the control group was 146.92 µm whereas in the experimental group was 124.53 µm, the mean difference between the two groups was 22.39 µm. There was a 6% decrease of cortical bone thickness. In conclusion, hypercholesterolemia can decrease cortical bone thickness of wistar rats (Rattus norvegicus).

scholarly journals The Effect of Hypercholesterolemia on Cortical Bone Thickness of Wistar Rats (Rattus norvegicus)

2019 ◽  
Vol 55 (1) ◽  
pp. 63
Author(s):  
Auliya Dzaqiyatus Sofka ◽  
Pudji Lestari ◽  
Gadis Meinar Sari
Keyword(s):  
Cortical Bone ◽  
Rattus Norvegicus ◽  
Wistar Rats ◽  
Protective Factor ◽  
Control Group ◽  
Standard Diet ◽  
Bone Thickness ◽  
Cortical Bone Thickness ◽  
Osteoblast Activity ◽  
Experimental Group

There have been several studies reporting the effect of hypercholesterolemia on cortical thickness, but it remains a controversy. Some studies suggest that hypercholesterolemia can decrease osteoblast activity and increase osteoclast activity. Meanwhile other studies suggest that hypercholesterolemia is a protective factor of osteoporosis. Therefore, it is necessary to conduct a study to determine the effect of hypercholesterolemia on cortical bone thickness. Method: This study used 8 rats (Rattus norvegicus) that were divided into 2 groups, including control group (K0) that was given standard diet and experimental group (K1) that was given high fat diet for 28 days and all were executed to obtain the femur bone. The cortical bone thickness was measured by using Optilab Viewer and Optilab Image Raster software. Result: The data analysis was conducted using independent t-test. A p value of <0.05 is considered significant. The results showed that hypercholesterolemia had significant effect on cortical bone thickness. The average cortical bone thickness in the control group was 146.92 µm whereas in the experimental group was 124.53 µm, the mean difference between the two groups was 22.39 µm. There was a 6% decrease of cortical bone thickness. In conclusion, hypercholesterolemia can decrease cortical bone thickness of wistar rats (Rattus norvegicus).

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