Assessment Of Stress Distribution Research Articles

Dental implant and abutment in PEEK: stress assessment in single crown retainers on anterior region.

Stress distribution assessment by finite elements analysis in poly(etheretherketone) (PEEK) implant and abutment as retainers of single crowns in the anterior region. Five 3D models were created, varying implant/abutment manufacturing materials: titanium (Ti), zirconia (Zr), pure PEEK (PEEKp), carbon fiber-reinforced PEEK (PEEKc), glass fiber-reinforced PEEK (PEEKg). A 50N load was applied 30o off-axis at the incisal edge of the upper central incisor. The Von Mises stress (σvM) was evaluated on abutment, implant/screw, and minimum principal stress (σmin) and maximum shear stress (τmax) for cortical and cancellous bone. The abutment σvM lowest stress was observed in PEEKp group, being 70% lower than Ti and 74% than Zr. On the implant, PEEKp reduced 68% compared to Ti and a 71% to Zr. In the abutment screws, an increase of at least 33% was found in PEEKc compared to Ti, and of at least 81% to Zr. For cortical bone, the highest τmax values were in the PEEKp group, and a slight increase in stress was observed compared to all PEEK groups with Ti and Zr. For σmin, the highest stress was found in the PEEKc. Stress increased at least 7% in cancellous bone for all PEEK groups. Abutments and implants made by PEEKc concentrate less σvM stress, transmitting greater stress to the cortical and medullary bone. The best stress distribution in PEEKc components may contribute to decreased stress shielding; in vitro and in vivo research is recommended to investigate this.

Assessment of Stress Distribution with 3 Taper Design Preparation of Root Canal Using Finite Element Analysis.

Present research was done to assess stress distribution in three different taper design preparation of root canal with the help of finite element analysis. Lower incisors teeth having single canals that were cleaned and shaped with the help of NeoEndo Flex Titanium (NiTi) rotary file and later three designs were created such as 4%, 6%, and 8% canal preparation taper. Cone beam computed tomography (CBCT) was done for all teeth and subjected to finite element analysis for stresses. The collected data were statistically analyzed. Highest stress was found in the coronal followed by the middle and least in the apical part in all three designs. The highest stress value was found in enamel than dentin (MPa). The highest stress value was found with design 3 (8% taper) followed by designs 2 (6% taper) and 1 (4% taper) for enamel and dentin with either oblique or vertical stress loading. All canals preparation exhibited maximum enamel stress at the coronal load points compared to apical and middle portions. The stress increases with increase in canal tapering.

A Short Review of Through-Silicon via (TSV) Interconnects: Metrology and Analysis

This review investigates the measurement methods employed to assess the geometry and electrical properties of through-silicon vias (TSVs) and examines the reliability issues associated with TSVs in 3D integrated circuits (ICs). Presently, measurements of TSVs primarily focus on their geometry, filling defects, and the integrity of the insulating dielectric liner. Non-destructive measurement techniques for TSV contours and copper fillings have emerged as a significant area of research. This review discusses the non-destructive measurement of contours using high-frequency signal analysis methods, which aid in determining the stress distribution and reliability risks of TSVs. Additionally, a non-destructive thermal detection method is presented for identifying copper fillings in TSVs. This method exploits the distinct external characteristics exhibited by intact and defective TSVs under thermoelectric coupling excitation. The reliability risks associated with TSVs in service primarily arise from copper contamination, thermal fields in 3D-ICs, stress fields, noise coupling between TSVs, and the interactions among multiple physical fields. These reliability risks impose stringent requirements on the design of 3D-ICs featuring TSVs. It is necessary to electrically characterize the influence of copper contamination resulting from the TSV filling process on the reliability of 3D-ICs over time. Furthermore, the assessment of stress distribution in TSVs necessitates a combination of micro-Raman spectroscopy and finite element simulations. To mitigate cross-coupling effects between TSVs, the insertion of a shield between them is proposed. For efficient optimization of shield placement at the chip level, the geometric model of TSV cross-coupling requires continuous refinement for finite element calculations. Numerical simulations based on finite element methods, artificial intelligence, and machine learning have been applied in this field. Nonetheless, comprehensive design tools and methods in this domain are still lacking. Moreover, the increasing integration of 3D-ICs poses challenges to the manufacturing process of TSVs.

Assessment of Stress Distribution Around Dental Implants Based on the All-on-Four Treatment Concept using Finite Element Analysis.

The present study was conducted to assess stress distribution around dental implants based on the all-on-four treatment concept. The finite element analysis (FEA) models comprised cancellous bone covered with cortical bone. Four dental implants were placed in two different designs. In model 1, the four implants were placed parallel to each other, whereas, in model 2, the all-on-four concept was followed. The vertical and lateral loads of various values were applied, and stress was evaluated. In model 2, the least stress was observed in both lateral and vertical loading in the peri-implant region. The all-on-four concept proved to be beneficial in reducing the stress around dental implants, thereby reducing the treatment cost.

Assessment of stress distribution in premium connections with ultrasonic phased array and metal magnetic memory

The strength and sealing performance of premium connections in high temperature-high pressure (HTHP) gas well is one of the key factors for the integrity of wellbore, in which, the distribution of contact stress is the guarantee of metal-to-metal seals, while the stress distribution will affect the strength on the threaded connection. This paper explained the ultrasonic phased array (UPA) detection for contact stress of sealing surface and metal magnetic memory (MMM) detection for thread stress. The magnetic-acoustic detection test of the full-scale joints was carried out during make-up, with signals characterized the stress changes in the premium connections under the torque, the detection was also carried out during axial tension, with the contact stress of sealing surfaces quantitatively characterized by the reflection coefficient of sealing surfaces and the peak echo ratio between sealing surfaces and the inner wall of pipe. The variation of tangential component of magnetic field intensity has the same trend with that of threaded connection stress, which is linearly related to the change of contact stress in metal-to-metal seals. These findings show that the combination of UPA and MMM provides a reliable detection method for performance assessment on premium connections, both in quality control and in its field inspection.

Assessment of Stress Distribution Using Equator Attachment Design in Mandibular Implant-retained Overdentures in Comparison with Ball and Socket Attachment Design: 3D Finite Element Analysis

Assessment of Stress Distribution Using Equator Attachment Design in Mandibular Implant-retained Overdentures in Comparison with Ball and Socket Attachment Design: 3D Finite Element Analysis

Assessment of stress distribution using equator attachment in comparison with locator attachment design (A three-dimensional finite element analysis)

Objective: aiming to evaluate stress distribution in addition to compare different types of low-profile attachments for implant-retained mandibular overdenture. Objective: aiming to evaluate stress distribution in addition to compare different types of low-profile attachments for implant-retained mandibular overdenture. Materials and methods: The present study a simulated mandible the two attachments were examined after application of vertical and oblique 45° loads on the region of the premolar/molar. The results show Equators received less Von Mises stress than locators by about 40% under vertical loading. On the other hand, under oblique loading locators showed better performance and less Von Mises stress by about 10%. Conclusions: Equator attachment can be considered equivalent to locator attachment, while it may have better performance in certain situations. Tilting the applied load from vertical to oblique load dramatically increase the total deformation and Von Mises stress. Bone (cortical and spongy) and mucosa showed similar (equivalent) behavior under Equators and Locators attachments. Using equator attachments generated slightly less stresses on over-denture while using locators transfer less stresses to implants body and flexible caps.

Materials and Bioactive Factors in Dental Restoration and Periodontal Therapy.

Dental restoration and periodontal therapy have undergone tremendous expansion over the past few decades. Improvements have been made in basic and applied material science but also in clinical considerations of functional, esthetic, reparative, and regenerative aspects of materials and bioactive factors. This special issue offers a wide range of topics, broadening knowledge of researchers, dental specialists, and general dental practitioners. Dentin-adhesive bond remains a challenge in modern adhesive dentistry due to the complex composition and morphology of dentin. Different treatment modalities have been proposed to improve the dentin-adhesive bond and increase its longevity. Among these, conditioning dentin with ethylenediaminetetraacetic acid (EDTA) along with carbodiimide pretreatment have shown potential in preserving bond strength to dentin of self-etch adhesives over time. Impression materials should withstand tear and tensile forces and be able to recover fully for an ideal impression of intricate details of dental and oral structures. A number of hydrophilic elastomeric impression materials are available on the market. In vitro testing of tensile properties of heavy-body, medium-body, and light-body polyvinylsiloxane, polyether, and vinylpolyether silicone commercial products offers scientific data for clinical selection of impression materials for specific applications. Platelet-rich fibrin membranes seem to improve the healing process in periodontal regenerative treatments. Leukocyte- and platelet-rich fibrin (L-PRF) is considered a second-generation platelet concentrate, able to form strong fibrin matrices. Early L-PRF membranes have shown stronger mechanical properties, namely, tensile strength, modulus of elasticity, and toughness, than membranes obtained using platelet rich in growth factors (PRGF)/Endoret® technology, indicating potential clinical advantages. Titanium and titanium alloys are nowadays considered the material of choice for dental implant applications in the replacement of missing teeth. Numerous studies focus on the mechanisms of interaction between the surface of titanium or titanium alloys and host tissues. Recently, the role of titanium oxide surface layer in osteoblast differentiation has been studied in terms of alkaline phosphatase (ALP) activity. Increased ALP activity suggests that titanium oxide acts as a bioactive factor involved in osteoblast differentiation and subsequent osseointegration. Finite element analysis (FEA) has been used in assessment of stress distribution induced by occlusal loading in diverse dental tissues, restorations, implants, and surrounding alveolar bone (cancellous and cortical). FEA may be particularly useful in designing dental implants. Extensive numerical simulation reveals complex stress distribution in and around dental implants with different thread designs and abutment angulations restored with porcelain crowns and subjected to a number of occlusal loading conditions. Vesna Miletic Tihana Divnic-Resnik Natasa Nikolic Jakoba Andrija Petar Bosnjak Paulo Henrique Perlatti D'Alpino

Assessment of stress distribution around implant fixture with three different crown materials

ObjectivesSelection of crown material should be based on patient bone status. Therefore three different crown materials (in-ceram – porcelain fused to metal crowns – Acrylic) were investigated in this study. MethodsA 3D finite element model was constructed under Finite element package environment for the upper first premolar. Different loading conditions (vertical and oblique) form 18 case studies were analyzed for comparison. ResultsAccording to FEA results, changing crown material altered stresses and deformation values on cortical and spongy bones. Whereas linear static analysis results showed similar distributions, and safe values of stresses and deformations, that generated on all parts of the studied system. ConclusionsUsing softer (lower rigidity) crown material reduces the stresses generated on the jaw bone (cortical and spongy), that it absorbs more energy from the applied load, and transfers less energy to the following parts of the system (implant–abutment complex and bones).

Effect of Jig Design and Assessment of Stress Distribution in Testing Metal-Ceramic Adhesion.

In testing adhesion using shear bond test, a combination of shear and tensile forces occur at the interface, resulting in complex stresses. The jig designs used for this kind of test show variations in published studies, complicating direct comparison between studies. This study evaluated the effect of different jig designs on metal-ceramic bond strength and assessed the stress distribution at the interface using finite element analysis (FEA). Metal-ceramic (Metal: Ni-Cr, Wiron 99, Bego; Ceramic: Vita Omega 900, Vita) specimens (N = 36) (diameter: 4 mm, veneer thickness: 4 mm; base diameter: 5 mm, thickness: 1 mm) were fabricated and randomly divided into three groups (n = 12 per group) to be tested using one of the following jig designs: (a) chisel (CH) (ISO 11405), (b) steel strip (SS), (c) piston (PI). Metal-ceramic interfaces were loaded under shear until debonding in a universal testing machine (0.5 mm/min). Failure types were evaluated using scanning electron microscopy (SEM). FEA was used to study the stress distribution using different jigs. Metal-ceramic bond strength data (MPa) were analyzed using ANOVA and Tukey's tests (α = 0.05). The jig type significantly affected the bond results (p = 0.0001). PI type of jig presented the highest results (MPa) (p < 0.05) (58.2 ± 14.8), followed by CH (38.7 ± 7.6) and SS jig type (23.3 ± 4.2) (p < 0.05). Failure types were exclusively a combination of cohesive failure in the opaque ceramic and adhesive interface failure. FEA analysis indicated that the SS jig presented slightly more stress formation than with the CH jig. The PI jig presented small stress concentration with more homogeneous force distribution compared to the CH jig where the stress concentrated in the area where the force was applied. Metal-ceramic bond strength was affected by the jig design. Accordingly, the results of in vitro studies on metal-ceramic adhesion should be evaluated with caution. When adhesion of ceramic materials to metals is evaluated in in vitro studies, it should be noted that the loading jig type affects the results. Clinical observations should report on the location and type of ceramic fractures in metal-ceramic reconstructions so that the most relevant test method can be identified.

Assessment of stress distribution in ankle joint: simultaneous application of experimental and finite element methods

The goal of this study was to determine stress distribution in ankle joint by correlating with the strain distribution and its trend around tibia adjacent to the joint. Using an in-house device, an ankle from a cadaver was kept stable and loaded in various positions: neutral, dorsiflexion, plantar flexion, inversion and eversion. A total of six strain gauges were mounted around the shaft of the tibia, near the tibiotalar joint. This arrangement allowed us to measure deformations in the shaft of tibia. Patient-specific ankle joint geometry was generated from computed tomography data. The finite element model (FEM) of the ankle was validated using the experimental data logged by the strain gauges, and used for obtaining stress on the joint surface. A strong correlation was observed between the FEM and experimentally measured strains in magnitude (R = 0.94, P = 0.008), consequently stress distribution over the joint surface was obtained.

Holographic interferometry assessment of stress distribution in sandwich beams in bending

Abstract It is well known that there is a lack of experimental results on the thickness distributions of the displacements, strains and stresses in sandwich beams in bending. The present work aims to fill partially this lacuna through an experimental investigation. Use is made of a technique based on holographic interferometry. Some experimental results quantifying the thickness distributions of the displacements are presented and the limitations of the adopted technique are discussed. The investigation also highlights some interesting effect of the core deformability, which are essential in understanding the failure phenomena of sandwich structures subjected to concentrated loads.

Numerical assessment of stress distribution ahead of the crack tip for finite-width center cracked tension specimen

Numerical assessment of stress distribution ahead of the crack tip for finite-width center cracked tension specimen