Finite element analysis of fatigue life of commercially pure titanium clasps additively manufactured with different building orientations.

The geometrical accuracy of additively manufactured pure titanium clasps depends on the building orientation. The aim of this study is to compare the geometrical accuracy and the fatigue lives predicted by finite element analysis (FEA) among three clasps manufactured with different building orientations. Besides, this paper proposed a calculation method of the moment of inertia of area and cross-sectional area along with the arm as the geometrical parameters.

Mie-Resonant Nanophotonic-Enhancement of Asymmetry in Sodium Chlorate Chiral Crystallization.

Studies on chiral spectroscopy have recently demonstrated strong enhancement of chiral light-matter interaction in the chiral near-field of Mie resonance in high-refractive-index dielectric nanostructures by studies on chiral spectroscopy. This situation has motivated researchers to demonstrate effective chiral photosynthesis under a chiral near-field beyond circularly polarized light (CPL) as a chiral source. However, the effectivity of the chiral near-field of Mie resonance for chiral photosynthesis has not been clearly demonstrated.

Fatigue life prediction considering variability for additively manufactured pure titanium clasps.

Purpose: This study aims to develop a numerical prediction method for the average and standard deviation values of the largely varied fatigue life of additively manufactured commercially pure titanium (CPTi grade 2) clasps. Accordingly, the proposed method is validated by applying it to clasps of different shapes.

Methods: The Smith-Watson-Topper (SWT) equation and finite element analysis (FEA) were used to predict the average fatigue life.

Using digital image correlation to measure displacement and strain during involving distal movement of anterior teeth with clear aligner.

To investigate methods to suppress the bowing effects of lingual inclination and anterior tooth extrusion, digital image correlation (DIC) was used to evaluate aligner displacement in three-dimensions through comparing the distal movement of six and four anterior teeth. Computed tomography scans were used to measure aligner thickness and shape. Based on displacement direction and magnitude, a desirable deformation mode with minimal lingual inclination and extrusion was observed during distal movement of four anterior teeth.

Comparison of the fatigue life of pure titanium and titanium alloy clasps manufactured by laser powder bed fusion and its prediction before manufacturing.

Purpose: In this study, the fatigue properties of additively manufactured titanium clasps were compared with those of commercially pure titanium (CPTi) and Ti-6Al-4V (Ti64), manufactured using laser powder-bed fusion.

Methods: Fourteen specimens of each material were tested under the cyclic condition at 1 Hz with applied maximum strokes ranging from 0.2 to 0.

How Partial Skull Defect Affects Vulnerability of the Skull in Traumatic Situations: A Biomechanical Study.

Background: Part of the skull can be lost due to neurosurgical diseases or trauma. Skulls with partial defects can develop different fracture patterns from those of intact skulls. This study aims to clarify the differences.

Measurement of elastic strain recovery in an orthodontic aligner as a driving force for orthodontic treatment.

Orthodontic aligners undergo deformation during installation, producing an unexpected component of elastic restoring force that causes unintended changes in the dentition. The aim of this study was to investigate the relationship between strain and elastic recovery of the aligner. We distinguished the contributions to aligner deformation due to molding and installation by measuring the thickness distribution of an aligner after molding using micro-CT and tracking changes in grid patterns drawn on the sheet used to fabricate the aligner.

Probabilistic finite element analysis of fatigue life of additively manufactured clasp.

The present study was aimed to develop a probabilistic finite element method (FEM) that predicts the variability in the fatigue life of additively manufactured clasp so that it can be used as a virtual test in the design phase before manufacturing. Titanium alloy (Ti-6Al-4V) clasp with integrated chucking part, which was designed for experimental fatigue test to validate the computational method, was investigated. To predict the lower bound, an initial spherical defect was assumed in the region where stress concentration was predicted.

Biomechanical analysis of likelihood of optic canal damage in peri-orbital fracture.

Purpose: Detection of optic canal fractures is often difficult because of the subtleness of the fracture. If we could clarify impact on which region around the orbit is likely to accompany the fracture of the optic canal, the knowledge should be useful to make early diagnosis of optic canal fractures. The present study was conducted to elucidate this issue.

Influence of anisotropic bone properties on the biomechanical behavior of the acetabular cup implant: a multiscale finite element study.

Although the biomechanical behavior of the acetabular cup (AC) implant is determinant for the surgical success, it remains difficult to be assessed due to the multiscale and anisotropic nature of bone tissue. The aim of the present study was to investigate the influence of the anisotropic properties of peri-implant trabecular bone tissue on the biomechanical behavior of the AC implant at the macroscopic scale. Thirteen bovine trabecular bone samples were imaged using micro-computed tomography (μCT) with a resolution of 18 μm.

Development of a Drilling Simulator for Dental Implant Surgery.

The aim of this study was to develop and evaluate a dental implant surgery simulator that allows learners to experience the drilling forces necessary to perform an osteotomy in the posterior mandibular bone. The simulator contains a force-sensing device that receives input and counteracts this force, which is felt as resistance by the user. The device consists of an actuator, a load cell, and a control unit.

Scoring of Deformed Costal Cartilages Reduces Postoperative Pain after Nuss Procedure for Pectus Excavatum.

Objective: The present study aims to elucidate whether or not scoring deformed cartilages reduces postoperative pain after the Nuss procedure for pectus excavatum patients.

Methods: A total of 46 pectus excavatum patients for whom the Nuss procedure was conducted were included in the study. The patients were categorized into two groups, depending on whether or not the supplementary maneuver of scoring deformed cartilages was performed in addition to the Nuss procedure.

The "Sea" should not be operated on in scar revision for "Island-Like" scars.

Scars developing on body surfaces not only restrict body movement, but are also problematic from a cosmetic standpoint. Hence, revision is conducted by removing the scar and re-suturing the resultant defects. In performing scar revision, care should be taken to prevent the re-sutured wounds from developing hypertrophy again.

Irregular location of major pectoral muscle can be a causative factor of pectus excavatum.

Pectus excavatum-commonly known as funnel chest-is one of the most frequently observed congenital deformities, in which the patients' thoraces present concavity. This paper presents our original hypothesis that the abnormal positioning of the major pectoral muscle can be a potential factor in the occurrence of pectus excavatum, and evaluates the validity of the hypothesis by performing an anatomical and a biomechanical study. An anatomical study on clinical cases revealed that the major pectoral muscle tends to be positioned more superiorly in pectus excavatum patients than in normal persons.

Association between the peri-implant bone structure and stress distribution around the mandibular canal: a three-dimensional finite element analysis.

The aim of this study was to elucidate the association between the bone structure at implant insertion sites and stress distribution around the mandibular canal by means of three-dimensional finite element (3D FE) analysis. Four FE models were created with slice data using micro-computed tomography (micro-CT), and 3D FE analysis was performed. Mechanical analysis showed that the load reached the mandibular canal via the trabecular structure in all FE models.

Consideration of shear modulus in biomechanical analysis of peri-implant jaw bone: accuracy verification using image-based multi-scale simulation.

The aim of this study was to clarify the influence of shear modulus on the analytical accuracy in peri-implant jaw bone simulation. A 3D finite element (FE) model was prepared based on micro-CT data obtained from images of a jawbone containing implants. A precise model that closely reproduced the trabecular architecture, and equivalent models that gave shear modulus values taking the trabecular architecture into account, were prepared.

Transformation of keloids is determined by stress occurrence patterns on peri-keloid regions in response to body movement.

Keloids gradually change their shapes as they grow. We hypothesize that the change of keloid morphology reflects the incremental change of the stress patterns occurring in peri-keloid regions due to movement of the keloid-carrying body part. To examine the validity of this hypothesis, we used three-dimensional finite element analysis to calculate the stresses occurring in the peri-keloid regions of keloids on the chest in response to respiratory movement.

Stochastic multi-scale prediction on the apparent elastic moduli of trabecular bone considering uncertainties of biological apatite (BAp) crystallite orientation and image-based modelling.

An assessment of the mechanical properties of trabecular bone is important in determining the fracture risk of human bones. Many uncertainty factors contribute to the dispersion of the estimated mechanical properties of trabecular bone. This study was undertaken in order to propose a computational scheme that will be able to predict the effective apparent elastic moduli of trabecular bone considering the uncertainties that are primarily caused by image-based modelling and trabecular stiffness orientation.

Relationship between locations of rib defects and loss of respiratory function - a biomechanical study.

Objective: The present study elucidates the relationship between the locations of rib defects and loss of respiratory function.

Methods: Ten sets of three-dimensional finite element models were produced from computed tomography data of 10 persons and categorized as normal type models. These models were modified by removing part of the ribs, and the resultant models were categorized as defect type models.

Morphology analysis of vertebral trabecular bone under dynamic loading based on multi-scale theory.

Trabecular bone has a complicated porous microstructure and consists of interconnected plates and rods known as trabeculae. The microarchitecture of the trabeculae contributes to load distribution capacity and, particularly, the optimal bone strength. Many previous studies have shown that morphological parameters are used to characterize the microarchitecture of trabecular bone, but little is known about the mechanical role of trabecular morphology in the context of load-bearing behavior.

Biomechanical role of peri-implant cancellous bone architecture.

Purpose: The aim of this study was to investigate the biomechanical role of trabecular bone around dental implants in the mandible.

Materials And Methods: The model in this study was made using micro-computed tomography data taken from a cadaver in whom endosseous implants had been in place for 15 years prior to death. Morphologic analysis and three-dimensional (3D) finite element analysis were performed to calculate the peri-implant loading path of the model in which the trabecular structure was accurately simulated.

Biomechanical role of peri-implant trabecular structures during vertical loading.

The aim of this study was to identify the load transfer paths in cortical bone and trabecular structure of cancellous bone in the jawbones for loads from endosseous implants. Maxillae were resected from beagle dogs 6 months after implant surgery and imaged using micro-computed tomography (micro-CT). A three-dimensional structure was produced based on the CT data and peri-implant trabecular structure was observed.

[Assessment of bone quality. Biomechanics simulation for bone quality evaluation].

The outline of the novel multiscale biomechanics simulation is described, which bridges nanoscale, microscale and macroscale by considering both the three-dimensional network architecture of trabecular bone captured by means of micro-CT and the biological apatite crystallite orientation. The article covers the fundamentals of the stress analysis and the muliscale computational method including some important topics in the engineering field. And finally, the simulation of trabecular bone of human vertebra is presented.

Stress analysis of endodontically treated anterior teeth restored with different types of post material.

Finite element analysis was performed to evaluate stress distribution in maxillary central incisors treated endodontically and restored with a post and an all-ceramic crown. Tensile stress at tooth root was analyzed using two-dimensional finite element models with different post diameters and lengths. One post length was 1/3 of the root (short), while the other was 2/3 of the root (long); one post diameter was 1/3 of the root (narrow), while the other was 2/3 of the root (wide).

Feasibility of a curvature-based enhanced display system for detecting cerebral aneurysms in MR angiography.

Purpose: To assess the feasibility of a curvature-based enhanced display system for detecting cerebral aneurysms in MR angiography.

Methods: MR angiography studies of 18 patients (eight male and 10 female, average age 65.7, age range 50 to 75 years old) with 23 known aneurysms were evaluated with a curvature-based display system.