Finite Element Analysis Study Research Articles

A Biomechanical Evaluation of Distal Tilting Implants in All-on-Four Rehabilitation with Mild Mandibular Resorption: A Finite Element Analysis Study

A Biomechanical Evaluation of Distal Tilting Implants in All-on-Four Rehabilitation with Mild Mandibular Resorption: A Finite Element Analysis Study

The Effect of Implantoplasty on Fracture Resistance and Implant Surface Changes: An InVitro and Finite Element Analysis Study.

Implantoplasty can be performed on implants diagnosed with peri-implantitis to facilitate implant decontamination and improve access for oral home care. However, its effect on the mechanical strength of the implant is still uncertain. This study aimed to evaluate the effect of implantoplasty on the fracture resistance of dental implants with various degrees of bone loss, as well as its surface changes. Eighty 4.2 × 13 mm conical connection dental implants were allocated evenly into four groups based on the bone defect morphology: circumferential or semi-circumferential, and 3 or 5 mm vertical height. Half of the implants underwent implantoplasty with tungsten carbide finishing burs. Weight, volume, and surface roughness of the implants were recorded prior to and after instrumentation. All implants were subjected to static loading to failure or fracture and the implant surfaces were then analyzed using optical microscopy. Finite element analysis was carried out to assess the stress pattern on dental implants after implantoplasty. Implantoplasty significantly reduced the fracture resistance of implants with all defect morphologies, aside from those with 3 mm of circumferential bone loss. Implants with 5 mm of peri-implant bone loss also experienced significantly reduced fracture resistance compared to the 3 mm group. Significant decrease in fracture resistance was only observed between the circumferential and semi-circumferential groups with 5 mm of bone loss. Surface roughness was also significantly reduced following implantoplasty. The results from finite element analysis revealed a change in pattern of stress concentration in the implant after implantoplasty. Implantoplasty negatively impacted the fracture resistance of standard diameter dental implants in most scenarios. The increase in exposed implant length resulted in a decrease in fracture resistance. This increase in fracture risk should be considered prior to implantoplasty, especially in implants with more advanced bone loss.

Effects of pedicle subtraction osteotomy on aortic morphology and hemodynamics in ankylosing spondylitis with kyphosis: a finite element analysis study

Osteotomy can correct kyphosis, restore the spinal sequence, and restore the healthy appearance of a patient. However, the aorta is stretched during pedicle subtraction osteotomy (PSO), and some surgeons are concerned about aortic injury. We used finite element analysis to construct an aortic model to simulate hemodynamic changes during osteotomy. 16 patients with ankylosing spondylitis kyphosis who had undergone a two-level osteotomy at the L1 and L3 levels was included in this study. Aortic computed tomography angiography (CTA) was performed, and a 3D image model was constructed. The length, transverse diameter, and curvature of the aorta were used to evaluate morphological changes. Finite element analysis was used to analyze the changes in aortic fluid dynamics. Blood pressure, wall shear stress, and blood flow velocity were compared pre- and postoperatively. The overall length of the aorta before surgery was 424.3 ± 42.9 mm, and the overall length of the aorta after surgery was 436.2 ± 54.8 mm. The aortic curvature decreased from 0.27 ± 0.13 to 0.17 ± 0.09. The mean transverse diameter of the aorta did not change (19.3 ± 6.6 vs. 19.2 ± 7.4 mm, P > 0.05). The blood flow velocity (2.8 ± 1.1 vs. 1.5 ± 0.8 m/s, P < 0.05), blood pressure (6.6 ± 1.7 vs. 4.3 ± 1.2 Kpa, P < 0.05), and wall shear stress (47.6 ± 17.3 vs. 22.3 ± 8.6, P < 0.05) at the T10-L4 level decreased postoperatively. Changes in LL were significantly correlated with changes in ld, dc, blood flow velocity, blood pressure and wall shear stress (ld : r = 0.713, P < 0.001; dc: r = 0.626,P = 0.010; blood flow velocity: r= − 0.541, P = 0.041; blood pressure: r = − 0.601, P = 0.016; wall shear stress: r= − 0.594, P = 0.027). The aorta was stretched, and its curvature decreased. The mean transverse diameter of the aorta did not change. Blood flow velocity, blood pressure, and wall shear stress decreased after surgery. Our study provides hemodynamic support for the possible cardiovascular benefits of osteotomes.

Finite element analysis and optimization studies on tibia implant of SS 316L steel and Ti6Al4V alloy

Tibial fractures account for approximately 15% of all fractures, typically resulting from high-energy trauma. A critical surgical approach to treat these fractures involves the fixation of the tibia using a plate with minimally invasive osteosynthesis. The selection and fixation of the implant plate are vital for stabilizing the fracture. This selection is highly dependent on the plate's stability, which is influenced by factors like the stresses generated in the plate due to the load on the bone, as well as the plate's length, thickness, and number of screw holes. Minimizing these stresses is essential to reduce the risk of implant failure, ensuring optimal stress distribution and promoting faster, more effective bone healing. In the present work, the finite element and statistical approach was used to optimize the geometrical parameters of the implant plate made of SS 316L steel and Ti6Al4V alloy. A 3D finite element model was developed for analyzing the stresses and deformation, and implant plates were manufactured to validate the results with the help of an experiment conducted on the universal testing machine. A strong correlation was observed between the experimental and predicted results, with an average error of 8.6% and 8.55% for SS316L and Ti6Al4V alloy, respectively. Further, using the signal-to-noise ratio for the minimum stress condition was applied to identify the optimum parameters of the plate. Finally, regression models were developed to predict the stresses generated in SS316L and Ti6Al4V alloy plates with different input conditions. The statistical model helps us to develop the relation between different geometrical parameters of the Tibia implant plate. As determined by the present work, the parameter most influencing is implant plate length. This outcome will be used to select the implant for a specific patient, resulting in a reduction in implant failure post-surgery.

Evaluation and Comparison of Stresses Between All-on-4 and All-on-6 Treatment Concepts With Three Different Prosthetic Materials in the Maxilla: A Finite Element Analysis Study.

This study aimed to evaluate the comparative analysis of stresses on and around implants and surrounding cortical bone using three different prosthetic materials in hybrid prosthesis using the all-on-4 technique and all-on-6 technique in the maxilla using finite element analysis (FEA). An in vitro FEA study was conducted where a three-dimensional (3D) model of an edentulous maxilla and four different models of the mandible were built using ANSYS software version 18 (Ansys, Inc., Canonsburg, Pennsylvania, United States). Group A comprised the all-on-4 technique where two vertical implants were placed in the lateral incisor area, and two tilted implants at 30o were placed in the second premolar area, whereas group B included the all-on-6 technique, where four vertical implants were placed in the central incisor and canine area, along with two tilted implants in second premolar area. Subsequently, prosthetic materials such as acrylic, porcelain fused to metal (PFM), and zirconia were studied. Four different opposing arch materials were made: natural teeth (A1 and B1), complete dentures (A2 and B2), implant-supported overdentures (A3 and B3), and hybrid prosthesis (A4 and B4). The von Mises stresses were recorded at the implant and cortical bone to summarize the effect of occlusal loads on the maxillary bone using the all-on-4 and all-on-6 techniques. In the all-on-4 technique, on evaluating stresses on implants, it was revealed that acrylic consistently demonstrated lower stress magnitudes in comparison to zirconia and PFM. The stress levels escalate from 38.72 MPa in model A1 to 72.43 MPa in model A4. Zirconia endured the most substantial stresses, ranging from 53.64 MPa (A1) to 84.87 MPa (A4). Similar results were obtained for the stresses on the cortical bone and for the all-on-6 technique. However, the stresses were lower in the all-on-6 technique than in the all-on-4 technique. The lowest stress values across all prosthetic materials were recorded when the maxillary arch was restored with acrylic teeth along with a titanium bar opposing natural dentition. The least stresses were noticed in the all-on-6 technique with acrylic prosthetic material opposing the natural dentition. As the all-on-6 treatment concept showed the most favorable biomechanical behavior, it can be considered a viable alternative for moderate atrophic maxillary rehabilitation.

Effect of asymptomatic intervertebral flexion patterns on lumbar disc pressure: A finite element analysis study.

Movement patterns may be a factor for manipulating the lumbar load, although little information is yet available in the literature about the relationship between this variable and intervertebral disc pressure (IDP). A finite element model of the lumbar spine (49-year-old asymptomatic female) was used to simulate intervertebral movements (L2-L5) of 127 asymptomatic participants. The data from participants that at least completed a simulation of lumbar vertebral movement during the first 53% of a movement cycle (flexion phase) were used for further analyses. Then, for each vertebral angular motion curve with constant spatial peaks, different temporal patterns were simulated in two stages: (1) in lumbar pattern exchange (LPE), each vertebral angle was simulated by the corresponding vertebrae of other participants data; (2) in vertebral pattern exchange (VPE), vertebral angles were simulated by each other. The k-mean algorithm was used to cluster two groups of variables; peak and cumulative IDP, in both stages of simulations (i.e., LPE and VPE). In the second stage of the simulation (VPE), Kendall's tau was utilized to consider the relationship between different temporal patterns and IDPs for each individual lumbar level. Cluster analyses showed that the temporal movement pattern did not exhibit any effect on the peak IDP while the cumulative IDP changed significantly for some patterns. Earlier involvement in lumbar motion at any level led to higher IDP in the majority of simulations. There is therefore a possibility of manipulating lumbar IDP by changing the temporal pattern with the same ROM, in which optimal distribution of the loads among lumbar levels may be applied as preventive or treatment interventions. Evaluating load benefits, such as load, on biomechanically relevant lumbar levels, dynamically measured by quantitative fluoroscopy, may help inform interventional exercises.

Fatigue mechanisms at 450°C of a highly twined (>70%) and HIP-densified IN718 superalloy additively manufactured by laser beam powder bed fusion

Fatigue resistance at elevated temperatures is crucial for certifying aerospace structures additively manufactured by the laser beam powder bed fusion (PBF-LB) method with IN718 superalloy. This study employed a multi-step, supersolvus heat treatment process with hot isostatic pressing (HIP), called RHSA, to minimize pores and brittle phases. Stress intensity factor (△K) calculations using data from X-ray computed tomography and shape factors referencing finite element analysis (FEA) studies confirmed the suppression of △K below the threshold of conventional IN718 (∼5 MPa√m), shifting fatigue behavior to grain-structure-dominated. Despite a very high twin boundary (TB) fraction (>70%), fatigue tests at 450°C and R = 0.1 demonstrated low scatter. Slip trace analysis and high-resolution electron backscatter diffraction (EBSD) revealed that TB-induced strain concentration became prominent only at high △K, causing cracking at 45⁰ to the loading direction. The randomly oriented TBs with higher angles (60⁰) compared to high-angle grain boundaries (HAGBs) (30–40⁰) likely enhanced slip resistance and provided a net strengthening effect, which can explain the lower-than-average TB% along fracture paths. These insights suggest that a high TB fraction is not detrimental if fatigue stress is not excessive, alleviating concerns about annealing twins during defect minimization in AM IN718, allowing novel processes to improve fatigue resistance in PBF-LB IN718.

Comparative Analysis of Displacements and Stress Produced by Square and Rectangular Bracket Slot With Incremental Torque: A Finite Element Analysis Study.

This study aimed to perform a comparative analysis of stresses and displacements with incremental torque on the maxillary incisors and surrounding cortical bone using conventional metal brackets with rectangular slots and passive self-ligating brackets with square slots using finite element analysis (FEA). An in vitro FEA study was conducted, in which a three-dimensional (3D) model of the maxilla was built using ANSYS softwareversion 18 (ANSYS Inc., Canonsburg, PA). The conventional McLaughlin, Bennet, and Trevisi (MBT) bracket (3M Unitek, Monrovia, CA) of 0.022 × 0.028-inch slot with a 0.019 × 0.025-inch rectangular stainless steel (SS) archwire (model 1) was compared with the Pitts 21™ self-ligating bracket system (OC Orthodontics, McMinnville, OR) of 0.021 x 0.21-inch slot with a 0.020 × 0.020-inch square SS archwire (model 2) at incremental torques of 5°, 10°, 15°, and 20°. The von Mises stress was evaluated at the maxillary incisors and surrounding cortical bone. The torque moment, tipping angle, and displacement of the maxillary incisors were also measured and compared between the bracket systems. The highest torque expression of 13.8 N-mm was observed in model 2, compared to a torque expression of 10.68 N-mm in model 1. The torque expression increased in both models from 0°to 20°. There was a play of 6.2°at 20°torquein model 2, whereas it was 9.32°​​​​​​​play in model 1. The torque expressions were better for the lateral incisors than for the central incisors. Increased incremental torque was associated with increased proclination of the incisors, and this movement was more pronounced for the central incisor and model 1. Furthermore, it was revealed that the stresses on the cortical bone and teeth were higher in model 2 than in model 1. It was concluded that the Pitts 21™ passive self-ligating system produced better torque expression and less play with square SS archwire compared to conventional brackets with rectangular SS archwire.

The Effect of Different Separated File Retrieval Strategies on the Biomechanical Behavior of a Mandibular Molar: A Finite Element Analysis Study

IntroductionThis study evaluated the effects of retrieval strategies of separated nickel-titanium files on the biomechanical behavior of endodontically treated teeth by finite element analysis. MethodsSix FE models were created: intact tooth; simulated a scenario where the apical 3 mm of a nickel-titanium file is separated and retained; TD, simulated application of a trephine drill to expose 1 mm of the separated file; simulated troughing of 180° at the inner wall of root canal for an extra 1 mm of the separated file beyond the staging platform; simulated circumferential ultrasonic troughing done for an extra 1 mm after the TD; and PM, simulated iatrogenic perforation sealed using MTA. Occlusal loading followed the occlusal fingerprint of the tooth before maximum von Mises stresses, maximum principal stresses, safety factor, and number of cycles till failure were determined. The cervical region of the teeth and mid-root sections including the separated file was chosen as the areas of interest for further analysis. ResultsIntact tooth recorded the highest number of cycles till failure and safety factor. Other models showed a narrow range of variation in all aspects with the PM recording the lowest number of cycles till failure. The highest von Mises stress was recorded at the mesiobuccal line angle of the PM near its cervical margin, while the lowest was found at the intact tooth. ConclusionUnder the limitation of this study, various file retrieval strategies removing the surrounding root dentin within the amounts of general guidelines do not affect the biomechanical behavior of the tooth.

Finite Element Analysis Study to Calculate Stress, Restraint, and Displacement Values of an Elevated Oil Expansion Loop in Rumaila Oil Field

Finite Element Analysis Study to Calculate Stress, Restraint, and Displacement Values of an Elevated Oil Expansion Loop in Rumaila Oil Field

Comparative evaluation of pediatric endodontic rotary file systems to bending and torsion tests: A finite element analysis

Background and objectiveThe introduction of Paediatric NiTi instruments has transformed the field of paediatric endodontics. However, no studies are available on the mechanical behaviour of these files, wherein Finite Element Analysis (FEA) was found to play a major role. The objective of this study is to evaluate the mechanical behavior of three commercially available pediatric endodontic rotary file systems to bending and torsion stress analysis test through Finite Element Analysis (FEA). MethodsA Finite Element Analysis study was performed on three commercially available pediatric endodontic rotary files (Pro AF baby, Kedo SG and Neoendo pedoflex) available for cleaning and shaping the narrow root canals of the deciduous teeth to bending and torsion tests with the boundary conditions according to ISO 3630-1 specifications. ResultsIn the bending analysis, Pro AF baby files were found to withstand the complete bending tests without yielding with a maximum von Mises stress of 1366 MPa, and Kedo SG, Neoendo Pedoflex file exhibited maximum von Mises stress of 2296 MPa, 1971 MPa. Under torsion tests Kedo SG exhibited maximum stress distribution, while Neoendo Pedoflex and Pro AF baby files exhibited similar stress distribution. ConclusionPro AF baby file effectively withstood the rigorous 45 -degree bending examination without experiencing yielding, while Kedo SG file exhibited higher flexibility. Under torsional resistance test, all the three instruments exhibited similar stress distribution under the yield limit. In summary, the mechanical behaviour (bending and torsion) of pediatric rotary file systems were influenced by design of the files.

Finite element analysis and experimental study on the cutting mechanism of SiCp/Al composite in laser ultrasonic elliptic vibration turning

SiCp/Al composites have excellent material properties and are increasingly being used in the aerospace, military, and electronic packaging industries. However, the inhomogeneity and non-conductivity of conventional turning (CT) results in poor material surface quality and high cutting forces, which seriously hinder the application of particlereinforced metal matrix composites. The thermal softening property of laser-assisted turning (LAT) and the intermittent cutting property of two-dimensional (2D) ultrasonic elliptical vibratory turning (UEVT) offer unique advantages in improving material surface quality. Therefore, a novel laser ultrasonic elliptical vibratory turning (LUEVT) machining technique is proposed to improve the machining of SiCp/Al composites with two different volume fractions. The effect of highfrequency intermittent machining on material processing was further investigated by adjusting the pulsed laser power. Finite element modelling was used to predict the machining state, surface roughness, and chip morphology between the workpiece and the PCD tool. The effects of varying the machining parameters during the experiment on the two composites were analysed. The results showed that the LUEVT of 25 % and 45 % SiCp/Al composites were reduced by 39.3 % and 30.7 % respectively compared to the CT cutting forces. The experiments verified the consistency of the surface roughness and chip morphology with the finite element simulation results. The stability of the cutting force during the cutting process is also improved, as the material removal process mainly takes the form of small particle fragmentation and matrix encapsulation.

Tin Multilayer‐Aided SAC305‐Based Lead‐Free Solder Joint Interface with Cu: An Investigation of the Stress Distribution by Finite Element Analysis and Nanoindentation Studies

Two different types of lead‐free solder joints Cu/(Sn3.0Ag0.5Cu)/Cu and Cu/Sn/(Sn3.0Ag0.5Cu)/Sn/Cu have been investigated. Joints are produced following the transient liquid phase like soldering process. The microstructure of different intermetallic compounds (IMCs) present at the joint interfaces, as well as their indentation hardness and elastic modulus, have been investigated and analyzed using scanning electron microscopy (SEM), X‐ray diffraction (XRD) spectroscopy, and nanoindentation. The exact position of different microcracks inside the interfaces has been identified by analyzing the elastic–plastic properties and interfacial toughness of these solder joints. The modulus and hardness of the Sn multilayer‐assisted solder joint interface are found to be 60.08%, and 90.18% higher than those of its non‐layered counterpart, respectively. The finite element analysis (FEA) has been done to estimate and compute stress distributions over the interfacial region. The dislocation mechanics involved in strengthening the joint strength are related to the nature of stress flow; as observed in FEA. It is reconfirmed that the high susceptibility to brittle failure of the non‐layered Cu‐SAC305 solder joints could be avoided by using a Sn interlayer in between the Cu substrates and the SAC305 solder paste.

Comparison of stress distribution around splinted and nonsplinted implants with different crown height space in posterior mandible: A finite element analysis study.

The purpose of this finite element analysis (FEA) study was to analyze the stress distribution on prosthetic components of splinted and nonsplinted prostheses, bone, and implants with different crown height space (CHS). Mandibular posterior segment was modeled with no resorption at the second premolar site and various amounts of resorption (0, 3, 6, and 9mm) at the first molar site. Two adjacent implants (Straumann bone level implants, 4.1 mm×8mm) were placed; at the second premolar site, the crown height was 8mm and at the first molar site, the crown height varied (8, 11, 14, and 17mm), depending on the amount of resorption. Both splinted and nonsplinted crowns were designed. Vertical and oblique loads of 400 N were applied to the crowns. von Mises stress was used to evaluate the stress distribution in the implant complex and maximum principal stress was used to evaluate the stress in the bone. When oblique forces were applied, the highest von Mises stresses were observed for nonsplinted crowns in the 17mm CHS group. The maximum principal and minimum principal stresses observed in bone under oblique loading increased with increased CHS for nonsplinted restorations. Crown height affected the amount of stress in bone and implant components. When the crown height difference between two adjacent implants increases, splinting may be crucial.

Parametric Analysis of Critical Buckling in Composite Laminate Structures under Mechanical and Thermal Loads: A Finite Element and Machine Learning Approach.

This research focuses on investigating the buckling strength of thin-walled composite structures featuring various shapes of holes, laminates, and composite materials. A parametric study is conducted to optimize and identify the most suitable combination of material and structural parameters, ensuring the resilience of structure under both mechanical and thermal loads. Initially, a numerical approach employing the finite element method is used to design the C-section thin-walled composite structure. Later, various structural and material parameters like spacing ratio, opening ratio, hole shape, fiber orientation, and laminate sequence are systematically varied. Subsequently, simulation data from numerous cases are utilized to identify the best parameter combination using machine learning algorithms. Various ML techniques such as linear regression, lasso regression, decision tree, random forest, and gradient boosting are employed to assess their accuracy in comparison with finite element results. As a result, the simulation model showcases the variation in critical buckling load when altering the structural and material properties. Additionally, the machine learning models successfully predict the optimal critical buckling load under mechanical and thermal loading conditions. In summary, this paper delves into the study of the stability of C-section thin-walled composite structures with holes under mechanical and thermal loading conditions using finite element analysis and machine learning studies.

Effect of different post materials and designs on upper central tooth torque and intrusion load: A finite element analysis study

The aim of this study was to examine the effects of post material type and the presence of ferrules on the torque and intrusion load of the upper central tooth using finite element analysis. The upper central tooth and surrounding tissues (cortical bone, cancellous bone, and periodontal ligament) were modelled in three dimensions using the Spaceclaim software. Five simulated models (SM) different modifications were made to this main model: metal cast post (SM1) and glass fiber post-core with zirconium crown and without a ferrule (SM2), metal cast (SM3) post and glass fiber post with a ferrule and zirconium crown (SM4) and only zirconium crown (SM5). In all five simulations, in order to simulate lingual root torque movement, a total load of 40grams was applied to the bracket slot as 20grams of force couples and in order to simulate intrusion movement, a load of 40grams was applied to the superior wall of the bracket slot. The stress caused by the applied loads on the root surfaces was determined using finite element analysis. Maximum principal stress (MPS) value was used in the comparison. The highest root surface MPS values for both intrusion and torque loads belonged to SM2 (3.864 and 0.379MPa, respectively). The presence of ferrules in both intrusion and torque loads reduced the stress by approximately half (from 3.864 to 2.004MPa). In all five models, the radicular area with higher stress was located in the cervical third on the lingual surface when both torque and intrusion loads were applied. The amount and localization of stress was affected by the type of post material. The variation in stress values between the materials remains within a safe range (0.099 and 3.87MPa), making both materials suitable for use under orthodontic forces.

Anterior percutaneous full-endoscopic transcorporeal decompression for cervical disc herniation: a finite element analysis and long-term follow-up study

ObjectiveThe purpose of this study was to investigate the long-term consequences on the cervical spine after Anterior transcorporeal percutaneous endoscopy cervical discectomy (ATc-PECD) from the biomechanical standpoint.MethodsA three-dimensional model of the normal cervical spine C2-T1 was established using finite element method. Subsequently, a disc degeneration model and degeneration with surgery model were constructed on the basis of the normal model. The same loading conditions were applied to simulate flexion, extension, lateral bending and axial rotation of the cervical spine. We calculated the cervical range of motion (ROM), intradiscal pressure, and intravertebral body pressure under different motions for observing changes in cervical spine biomechanics after surgery. At the same time, we combined the results of a long-term follow-up of the ATc-PECD, and used imaging methods to measure vertebral and disc height and cervical mobility, the Japanese Orthopaedic Association (JOA) score and visual analog scale (VAS) score were used to assess pain relief and neurological functional recovery.ResultsThe long-term follow-up results revealed that preoperative JOA score, neck VAS score, hand VAS score, IDH, VBH, and ROM for patients were 9.49 ± 2.16, 6.34 ± 1.68, 5.14 ± 1.48, 5.95 ± 0.22 mm, 15.41 ± 1.68 mm, and 52.46 ± 9.36° respectively. It changed to 15.71 ± 1.13 (P < 0.05), 1.02 ± 0.82 (P < 0.05), 0.77 ± 0.76 (P < 0.05), 4.73 ± 0.26 mm (P < 0.05), 13.67 ± 1.48 mm (P < 0.05), and 59.26 ± 6.72° (P < 0.05), respectively, at 6 years postoperatively. Finite element analysis showed that after establishing the cervical spondylosis model, the overall motion range for flexion, extension, lateral bending, and rotation decreased by 3.298°, 0.753°, 3.852°, and 1.131° respectively. Conversely, after establishing the bone tunnel model, the motion range for these actions increased by 0.843°, 0.65°, 0.278°, and 0.488° respectively, consistent with the follow-up results. Moreover, analysis of segmental motion changes revealed that the increased cervical spine mobility was primarily contributed by the surgical model segments. Additionally, the finite element model demonstrated that bone tunneling could lead to increased stress within the vertebral bodies and intervertebral discs of the surgical segments.ConclusionsLong-term follow-up studies have shown that ATc-PECD has good clinical efficacy and that ATc-PECD can be used as a complementary method for CDH treatment. The FEM demonstrated that ATc-PECD can lead to increased internal stresses in the vertebral body and intervertebral discs of the operated segments, which is directly related to cervical spine degeneration after ATc-PECD.

Evaluation of the effect of different attachment configurations on molar teeth in maxillary expansion with clear aligners – a finite element analysis

ObjectiveTo evaluate the effects of different attachment configurations with and without buccal root torque on expansion movements achieved with aligners through finite element analysis (FEA).MethodsFEA modelling was done with 0.25 mm buccal expansion force application to the maxillary molars with different attachment configurations: Eight models were tested (1) no attachment (NA), (2) horizontal attachment (HA), (3) gingivally beveled horizontal attachment (GHA), and (4) occlusally beveled horizontal attachment (OHA), as well as models with 6obuccal root torque, (5) no attachment (TNA), (6) horizontal attachment (THA), (7) gingivally beveled horizontal attachment (TGHA), and (8) occlusally beveled horizontal attachment (TOHA).ResultsThe first and second molars exhibited buccal tipping in all models. The highest amount of buccal tipping for the molars was observed in the NA (6CMB, 0.232 mm; 6CMP, 0.246 mm; 7CMB, 0.281 mm; 7CMP, 0.312 mm) and GHA (6CMB, 0.230; 6CMP, 0.245; 7CMB, 0.279 mm; 7CMP, 0.311 mm) models, respectively, while the least tipping was observed in the TOHA model (6CMB, 0.155 mm; 6CMP, 0.168 mm; 7CMB, 0.216 mm; 7CMP, 0.240 mm). In all groups, the buccal tipping of the second molars was higher than that of the first molars.ConclusionThis FEA study showed that expansion with aligners tip maxillary molars buccally and the use of occlusally beveled attachments and addition of buccal root torque reduces uncontrolled buccal tipping.

Long head of the biceps tendon plays a role in stress absorption and humeral head restriction during the late cocking and deceleration phases of overhead throwing: a finite element study

BackgroundEmerging evidence suggests that the long head of the biceps (LHBT) may play a role in stabilizing the glenohumeral joint, and this has led to controversy around the efficacy of biceps tenotomy for superior labral anterior and posterior (SLAP) lesions. Therefore, the aim of this finite element analysis (FEA) study was to determine the stress absorption and humeral head translation restriction effects of the LHBT within the glenohumeral joint during the late cocking and deceleration phases of overhead throwing with a view to resolving the controversy around tenotomy. MethodsEight FEA models were created using computed tomography and magnetic resonance imaging data from normal glenohumeral joints. The models represented four LHBT conditions: uninjured, subpectoral tenodesis, tenotomy, and type II SLAP lesions. The late cocking and deceleration phases of the overhead throwing were simulated for each model. The impacts of the four LHBT conditions on glenohumeral joint stress absorption and humeral head displacement restriction were studied based on 1) stress and related distributions on the cartilage, labrum, capsule, and LHBT and 2) humeral head translation variation. ResultsThe FEA analysis showed that the magnitude of the contact stress on the articular cartilage, labrum, and capsule was the lowest in the uninjured models, followed by the subpectoral tenodesis, tenotomy, and type II SLAP lesion models. Humeral head translation was the most restricted in the subpectoral tenodesis models, followed by the tenotomy and type II SLAP lesion models. ConclusionFinite element analysis demonstrated that the LHBT plays a significant role in stress absorption and displacement restriction in the late cocking and deceleration phases of overhead throwing. Subpectoral tenodesis of the LHBT exhibited lesser amount of stress and humeral head translation than those of tenotomy, thereby making it a better option for patients who engage in overhead throwing.

Stress Distribution Pattern of a Calculated Standardized Force on Maxillary and Mandibular Jaws with Proclined Maxillary Anterior Teeth with and without the Use of Mouthguard: A 3D Finite Element Analysis.

To evaluate the stress distribution of calculated standardized force on maxillary and mandibular jaw bones with proclined maxillary anterior teeth with and without the use of a mouthguard. It's a finite element analysis (FEA) study. Maxillary and mandibular jaw models with and without mouthguard (4 mm) were created using a cone-beam computed tomography (CBCT) scan of a 13-year-old male patient with proclined maxillary anterior teeth. Calculated standardized forces were applied on the maxillary central incisors in the horizontal direction of the created model. The von Mises stresses (MPa) were analyzed on the maxillary and mandibular jaw. Higher von Mises stresses were analyzed in the maxillary and mandibular jaw model without a mouthguard compared to the model with a mouthguard. Forces were more evenly distributed in the maxillary and mandibular jaw models with a mouthguard. A mouthguard can be used to reduce and evenly distribute the stress on the maxillary and mandibular jaw with proclined maxillary anterior teeth when exposed to real-life situation forces. The force of injury is influenced by the size of the object or the velocity at which the athlete hits the object/individual. There is a need to evaluate the force at which the individual athlete hits the object/surface based on average height, weight, and velocity/performance at that particular age. As the age of the athlete's advances, there is a change in the height, weight as well as performance. This factor will influence the impact and severity of the trauma caused during sports activities. So, these parameters should be considered while designing the mouthguard for its better effectiveness. Doiphode AR, Kalaskar R. Stress Distribution Pattern of a Calculated Standardized Force on Maxillary and Mandibular Jaws with Proclined Maxillary Anterior Teeth with and without the Use of Mouthguard: A 3D Finite Element Analysis. Int J Clin Pediatr Dent 2024;17(S-1):S61-S66.