The relations between the stress in temporomandibular joints and the deviated distances for mandibular asymmetric patients

2020 ◽  
Vol 235 (1) ◽  
pp. 109-116
Author(s):  
Jingheng Shu ◽  
Xin Xiong ◽  
Desmond YR Chong ◽  
Yang Liu ◽  
Zhan Liu
Keyword(s):  
Temporomandibular Disorders ◽  
Three Dimensional ◽  
Control Group ◽  
Case Group ◽  
Principal Stresses ◽  
Biomechanical Stress ◽  
Mandibular Asymmetry ◽  
Temporomandibular Joints ◽  
The Difference ◽  
Three Dimensional Finite Element

The study aimed to compare the difference of stress distributions in temporomandibular joints (TMJs) between the patients with mandibular asymmetry and asymptomatic subjects and find the relations between deviated distance and biomechanical stress using three-dimensional finite element method, to give guidance to dentists for correction of mandibular asymmetry. Ten facial symmetric subjects without symptoms of temporomandibular disorders (TMD) and 10 mandibular asymmetric patients were recruited and assigned as the Control and Case group respectively. The FE models of the mandible and maxilla were reconstructed from cone-beam computed tomography (CBCT) images. Muscle forces and boundary conditions were applied to the two groups corresponding to centric and anterior occlusions. The simulation manifested significant differences in stresses of the TMJs between the non-deviated and deviated sides in the Case group under the centric and anterior occlusions. The stresses in the Case group were significantly greater than those in the Control group, especially on the non-deviated side. Besides, there were weak and moderate correlations between the third principal stresses and deviated distances for the patients under centric and anterior occlusions. The excessive stresses in the TMJ of patients with mandibular asymmetry were associated with temporomandibular disorders.

scholarly journals How many implants are needed for mandibular full-arch rehabilitation?

2020 ◽  
Vol 19 ◽  
pp. e209191
Author(s):  
Karina Giovanetti ◽  
Ricardo Armini Caldas ◽  
Paulo Henrique Ferreira Caria
Keyword(s):  
Bone Tissue ◽  
Principal Stress ◽  
Three Dimensional ◽  
Maximum Principal Stress ◽  
Von Mises Stress ◽  
Principal Stresses ◽  
Dimensional Finite Element ◽  
The Difference ◽  
Von Mises ◽  
Three Dimensional Finite Element

Aim: To analyze the stress distribution at the peri-implant bone tissue of mandible in full-arch implant-supported rehabilitation using a different number of implants as support. Methods: Three-dimensional finite element models of full-arch prosthesis with 3, 4 and 5 implants and those respective mandibular bone, screws and structure were built. ANSYS Workbench software was used to analyze the maximum and minimum principal stresses (quantitative analysis) and modified von Mises stress (qualitative analysis) in peri-implant bone tissue after vertical and oblique forces (100N) applied to the structure at the cantilever site (region of the first molars). Results: The peak of tensile stress values were at the bone tissue around to the distal implant in all models. The model with 3 implants presented the maximum principal stress, in the surrounding bone tissue, higher (~14%) than the other models. The difference of maximum principal stress for model with 4 and 5 implants was not relevant (~1%). The first medial implant of the model with 5 implants presented the lower (17%) stress values in bone than model with 3 implants. It was also not different from model with 4 implants. Conclusion: Three regular implants might present a slight higher chance of failure than rehabilitations with four or five implants. The use of four implants showed to be an adequate alternative to the use of classical five implants.

The Measurement of Stresses in Composites

1986 ◽  
Vol 1 (2) ◽  
pp. 15-21 ◽  
Author(s):  
J. B. Cohen
Keyword(s):  
Three Dimensional ◽  
Stress System ◽  
Principal Stresses ◽  
Reasonable Time ◽  
Complete Measurement ◽  
Useful Life ◽  
Diffraction Peaks ◽  
The Difference ◽  
Full Investigation ◽  
Hydrostatic Component

AbstractAlthough there is mounting interest in the measurement of stresses in composite materials after fabrication and/or use, few measurements to date have not taken into account the three dimensional nature of the stress system in such materials. Most data give only the net stress, that is, the difference between principal stresses. A procedure for a more complete measurement (in a reasonable time) is developed here, including the separation of macrostresses and microstresses. If time does not permit a full investigation, measurements of the lattice parameters of the component phases provide a simple way to sample the hydrostatic component due to differential thermal contraction. The Barrett-Predecki method of adding filler is particularly promising for stress measurements in those composites whose component phases do not give appropriate diffraction peaks. This procedure could also be used for monitoring stresses during the useful life of such materials.

scholarly journals Association between family history and the onset age of essential hypertension in Han population in Shanghai China

2019 ◽  
Author(s):  
li anle ◽  
Qian Peng ◽  
Yue Qin Shao ◽  
Yi Ying Zhang ◽  
Fang Xiang
Keyword(s):  
Essential Hypertension ◽  
Family History ◽  
Genetic Factors ◽  
Nuclear Family ◽  
Age Of Onset ◽  
Control Group ◽  
Case Group ◽  
Onset Age ◽  
Han Population ◽  
The Difference

Abstract Importance Genetic factors are important influencing factors of essential hypertension, and family history (FH) is an important marker of genetic factors. Objective To explore the association between family history and the onset age of essential hypertension in Han population in Shanghai China. Methods According to l:l matched pairs design，342 precursor of hypertension and 342 controls were selected and investigate their nuclear family members in the case-control study. The diagnostic information of hypertension in all relatives of these two groups was investigated. The method of genetic epidemiology research was used to explore the effect of family history. Results The average prevalence of hypertension was 23.32%. The prevalence of hypertension of first-degree relatives was 33.99%; the prevalence of second- degree relatives was 17.60%; the prevalence of third-degree relatives was 13.51%. All prevalence of hypertension of case group relatives were significantly higher than that of control group relatives. The average onset age in population with positive FH is 48.74±11.16 years old, and the average onset age in population with negative FH is 54.38±9.87 years old. The difference about two FH groups showed statistically significant (t=4.589, P<0.001). The average onset age of offspring with father, mother, grandpa, grandma, maternal grandpa or maternal grandma positive was respectively 48.42± 11.16, 49.16±11.12, 39.55±11.95, 39.88±11.90, 43.67±9.77 or 43.64±10.21 years old; and the average onset age of children with father, mother, grandpa, grandma, maternal grandpa or maternal grandma negative was respectively 51.90± 10.81, 51.17±11.04, 51.07±10.59, 51.08±10.60, 50.50±11.09 or 50.57±11.06 years old. The difference about two groups showed statistically significant. Conclusion Family history has a positive effect on the occurrence of hypertension, and lead to earlier age of onset of offspring. The effects are different among parent and grandparent in Han in Shanghai China.

Prevalence of ADHD in children born by mothers consuming Frankincense during pregnancy

2021 ◽  
Author(s):  
Alimohammad Ranjbar ◽  
Elahe Kamali Ardakani ◽  
Rahele Zareshahi
Keyword(s):  
Data Gathering ◽  
Control Group ◽  
Case Group ◽  
Dsm V ◽  
History Of ◽  
The Difference ◽  
The Impact ◽  
The Relationship ◽  
The Brain ◽  
Positive Effect

Aims: In Iranian culture, due to some narratives from the prophet Mohammad about the use of frankincense during pregnancy for increasing IQ in children, some women consume frankincense during expectancy. This study's goal is to evaluate the relationship between frankincense used during pregnancy and the incidence of ADHD. Methods: In this study, the case group comprised children 4-17 years old referring to Shahid Chamran Pharmacy in Yazd from summer to winter 2018 for receiving Methylphenidate, those with whom a psychologist had identified ADHD based on DSM-V factors.  The control group included children of the same age group but without ADHD. For data gathering, a checklist was used with some questions on smoking, family history of ADHD, presence/absence of a specific disease during pregnancy, frankincense used during pregnancy, and a chemical medication consumed during pregnancy. Results: The main result demonstrated that the children whose mothers used frankincense during pregnancy were 0.67 times less likely to be affected by ADHD than those whose mothers did not use this substance. However, the difference failed to be statistically significant (P>0.05). Conclusion: Some studies report that frankincense can bear a positive effect on the development of the brain and possibly adequate formation of dendrites trees, axons and induce proper communication between them, so the impact of frankincense on the brain may be justified by its protective effect against the hyperactive child.

A Stress Analysis and Strength Evaluation of Scarf Adhesive Joints Subjected to Static Tensile Loading

2006 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Masahiro Sasaki ◽  
Yuya Hirayama
Keyword(s):  
Joint Strength ◽  
Three Dimensional ◽  
Maximum Principal Stress ◽  
Adhesive Joints ◽  
Stress Distributions ◽  
Principal Stresses ◽  
Adhesive Properties ◽  
Maximum Value ◽  
Static Tensile ◽  
Three Dimensional Finite Element

Scarf adhesive joints used in practice. However, the stress distributions and the joints strengths have not yet been fully elucidate. Important issues are how to determine the scarf angle in adherend and how to determine the adhesive properties. In this study, the stress distributions in scarf adhesive joints under static tensile loadings are analyzed using three-dimensional finite-element calculations. In the FEM calculations, the effects of Young's modulus of the adhesive, adhesive thickness, scarf angle of the adherend on the stress distributions at the adhesive interfaces are examined. The maximum principal stresses were calculated at every element at the interfaces. As the results, it is found that the maximum value of the maximum principal stress occurs at the edge of the adhesive interfaces (z=0, 1/s=1). It is also observed that the maximum value of the stress is the smallest, when the scarf angle is 60 degree. In addition, the joint strength is estimated using the interface stress. For the verification of the FEM calculations, the experiments were carried out to measure the strengths and the strains in the joints under static tensile loadings using strain gauges. Fairly good agreements are observed between the numerical and the measured results concerning the joint strength and the strains.

A comparative study between zirconia and titanium abutments on the stress distribution in parafunctional loading: A 3D finite element analysis

2020 ◽  
Vol 28 (6) ◽  
pp. 603-613 ◽  
Author(s):  
Efe Can Sivrikaya ◽  
Mehmet Sami Guler ◽  
Muhammed Latif Bekci
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Principal Stresses ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
3D Fea ◽  
Von Mises ◽  
Three Dimensional Finite Element

BACKGROUND: Zirconia has become a popular biomaterial in dental implant systems because of its biocompatible and aesthetic properties. However, this material is more fragile than titanium so its use is limited. OBJECTIVES: The aim of this study was to compare the stresses on morse taper implant systems under parafunctional loading in different abutment materials using three-dimensional finite element analysis (3D FEA). METHODS: Four different variations were modelled. The models were created according to abutment materials (zirconia or titanium) and loading (1000 MPa vertical or oblique on abutments). The placement of the implants (diameter, 5.0 × 15 mm) were mandibular right first molar. RESULTS: In zirconia abutment models, von Mises stress (VMS) values of implants and abutments were decreased. Maximum and minimum principal stresses and VMS values increased in oblique loading. VMS values were highest in the connection level of the conical abutments in all models. CONCLUSIONS: Using conical zirconia abutments decreases von Mises stress values in abutments and implants. However, these values may exceed the pathological limits in bruxism patients. Therefore, microfractures may be related to the level of the abutment.

Comparison of Gait Pattern in Athletes with ACL Deficiency and Healthy Individual using an Accelerometer

2020 ◽  
Vol 8 (1) ◽  
pp. 43 ◽  
Author(s):  
Heydar Sadeghi ◽  
Hesam Fazlali ◽  
Saba Sadeghi ◽  
Seyedmojtaba Seyedmojtaba Ojaghi
Keyword(s):  
Cruciate Ligament ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Gait Pattern ◽  
Control Group ◽  
Acl Deficiency ◽  
Functional Capabilities ◽  
The Difference ◽  
Anterior Cruciate

Background: In athletes with anterior cruciate ligament (ACL) deficiencies could assess functional capabilities with different instruments such as use of a camera in vivo situation. However, these methods have suffered from a large number of limitations such as inability to be repeatable and complexity in technique. Objective: The main purpose of this study was to compare gait pattern of the athletes with ACL injury and able-bodied subjects using an accelerometer. Method: A three-dimensional accelerometer was placed over the tibia tuberosity of 20 healthy and 20 individuals with ACL-deficiencies (ACLD). After walking on the treadmill, the principal components of the acceleration data were calculated using MATLAB software. Results: In this study, Principle Component analysis was used for statistical analysis. The results indicated that subjects with ACL deficiency have different gait pattern compared to the control group. The major differences between stride trajectories of the two groups were at the end of mid-swing and the beginning of terminal swing phases in vertical axis. ACL deficient subjects exhibited different gait patterns during mid and terminal stance phases in anterior- posterior axis compared with normal controls. Conclusions: The difference in gait between subjects with ACL deficiency and healthy subjects are depends on variation in the amount of knee flexion and tibia rotation that could be altered to motor recruitment.

scholarly journals Comparison of the Effect of Combined Treatment with Radiotherapy and Hyperthermia versus Exclusively Radiotherapy to Reduce Pain in Patients with Bone Metastases

2020 ◽  
pp. 23-34
Author(s):  
Baharak Keyvan ◽  
Alireza Nikoofar ◽  
Mastaneh Sanei ◽  
Mohammadreza Barzegar- Tahamtan ◽  
Seyed Rabi Mahdavi ◽  
...  
Keyword(s):  
Bone Metastases ◽  
Combined Treatment ◽  
Complete Response ◽  
Capital City ◽  
Response To Treatment ◽  
Control Group ◽  
Case Group ◽  
Stable Mode ◽  
Significant Difference ◽  
The Difference

Based on the extant studies conducted by scholars, recognizing the best and practical treatment methods in patients with bone metastases is an important and conspicuous focus in improving and amelioration of the treatment and prognosis of patients. Ergo, this study aims to compare the effects of radiotherapy and hyperthermia with radiotherapy only to reduce pain in one of the oncology centers located in Tehran (the capital city of Iran). In this randomized clinical trial study, patients with bone metastases were randomly assigned to one of two group’s radiotherapy and hyperthermia or radiotherapy exclusively and the collected data were processed through Statistical Package of Social Science (SPSS). Thenceforth, findings were evaluated and compared between the two groups. A total of 60 patients inclusive of 34 women and 26 men were investigated. In the baseline, 20 patients in the case group (67%) and 21 patients in the control group (70%) used palliative drugs. At the end of the trial, the consumption of palliative drugs was decreased in the case group (12 patients, 43%) but, no change was observed in the control group. After treatment, complete response to treatment (27% vs. 13%), experienced a decrease in the clinical pain (57% vs. 83%) and did not respond to treatment in a stable mode (17% vs. 4%) of which were different between case and control groups, respectively. Regardless of the difference in the ratio of partial response in two groups, there was no significant difference between the two groups in terms of response to treatment. Although the effect of radiotherapy and hyperthermia in comparison with radiotherapy exclusively was more efficacious in some aspects of the intervention of pain with sleep. However, there was no remarkable and significant difference in other cases.

scholarly journals Association of Genetic Polymorphism of GSTM1 and GSTT1 with the Susceptibility to Antituberculosis Drug-induced Hepatotoxicity in Chinese Population

2018 ◽  
Vol 1 (3) ◽  
pp. 80
Author(s):  
Gang Xiao
Keyword(s):  
Liver Toxicity ◽  
Control Group ◽  
Case Group ◽  
Antituberculosis Drug ◽  
Drug Induced ◽  
Antituberculous Treatment ◽  
Gstm1 Gene ◽  
Gstt1 Gene ◽  
The Difference ◽  
And Control

Objective To investigate the relationship between the polymorphism of glutathione S transferase M1, T1(GSTM1, GSTT1) gene and the susceptibility to antituberculosis drug induced hepatotoxicity (ATDH) in patients with tuberculosis. Methods GSTM1 and GSTT1 gene polymorphisms in patients with or without liver toxicity after antituberculous treatment were analyzed using multiple PCR method. Results In ATDH group and control group, the proportion of GSTM1 gene deletion was 58.0% and 50.7%respectively, and the difference was not statistically signifcant (OR=1.322, 95%CI=0.921~1.878), the frequencies of GSTT1 deletion were 46.3% and 49.3%, respectively, and there was no signifcant difference between them. There was no signifcant difference in frequency of GSTM1 and GSTT1 variation between case group and control group (P> 0.05), and no synergistic effect of those two gene polymorphism were detected in the occurrence of antituberculosis drug-induced hepatotoxicity. Conclusion The polymorphisms of GSTM1 and GSTT1 genes may not be associated with the risk of ATDH.

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