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16 pages, 2224 KiB  
Article
Electromagnetic Noise and Vibration Analyses in PMSMs: Considering Stator Tooth Modulation and Magnetic Force
by Yeon-Su Kim, Hoon-Ki Lee, Jun-Won Yang, Woo-Sung Jung, Yeon-Tae Choi, Jun-Ho Jang, Yong-Joo Kim, Kyung-Hun Shin and Jang-Young Choi
Electronics 2025, 14(14), 2882; https://doi.org/10.3390/electronics14142882 - 18 Jul 2025
Viewed by 380
Abstract
This study presents an analysis of the electromagnetic noise and vibration in a surface-mounted permanent magnet synchronous machine (SPMSM), focusing on their excitation sources. To investigate this, the excitation sources were identified through an analytical approach, and their effects on electromagnetic noise and [...] Read more.
This study presents an analysis of the electromagnetic noise and vibration in a surface-mounted permanent magnet synchronous machine (SPMSM), focusing on their excitation sources. To investigate this, the excitation sources were identified through an analytical approach, and their effects on electromagnetic noise and vibration were evaluated using a finite element method (FEM)-based analysis approach. Additionally, an equivalent curved-beam model based on three-dimensional shell theory was applied to determine the deflection forces on the stator yoke, accounting for the tooth-modulation effect. The stator’s natural frequencies were derived through the characteristic equation in free vibration analysis. Modal analysis was performed to validate the analytically derived natural frequencies and to investigate stator deformation under the tooth-modulation effect across various vibration modes. Furthermore, noise, vibration, and harshness (NVH) analysis via FEM reveals that major harmonic components align closely with the natural frequencies, identifying them as primary sources of elevated vibrations. A comparative study between 8-pole–9-slot and 8-pole–12-slot SPMSMs highlights the impact of force variations on the stator teeth in relation to vibration and noise characteristics, with FEM verification. The proposed method provides a valuable tool for early-stage motor design, enabling the rapid identification of resonance operating points that may induce severe vibrations. This facilitates proactive mitigation strategies to enhance motor performance and reliability. Full article
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15 pages, 5462 KiB  
Article
Contemporary Magnetic Removable Partial Denture Utilizing a Novel Ultra-Thin Magnetic Attachment System
by Adityakrisna Yoshi Putra Wigianto, Yuichi Ishida, Kohei Kamoi, Takaharu Goto, Kazumitsu Sekine, Megumi Watanabe and Tetsuo Ichikawa
Dent. J. 2025, 13(7), 278; https://doi.org/10.3390/dj13070278 - 20 Jun 2025
Viewed by 647
Abstract
Background/Objectives: Recently, a novel magnetic attachment system was introduced to improve performance. Using the same technology, a new ultra-thin magnetic attachment (UTMA) was possible to produce. This study aimed to evaluate the feasibility of a magnet-retained telescopic partial denture (MTPD) utilizing the new [...] Read more.
Background/Objectives: Recently, a novel magnetic attachment system was introduced to improve performance. Using the same technology, a new ultra-thin magnetic attachment (UTMA) was possible to produce. This study aimed to evaluate the feasibility of a magnet-retained telescopic partial denture (MTPD) utilizing the new UTMA. Methods: This in vitro study was performed using a titanium master model representing prepared lower first-premolar and second-molar abutment teeth. The inner crowns (ICs) (h: 4 mm, 4° taper) and four-unit MTPDs were fabricated via computer-aided design/computer-aided manufacturing (CAD/CAM) using zirconia. A Ø4 mm UTMA system (magnet assembly and keeper thickness: 0.6 mm and 0.4 mm, respectively) was cemented into the MTPD and the ICs using dual-cure resin cement. A load of 100 N was applied along with 10,000 insertion–removal cycles. The MTPD retentive force was measured before and after every set of 1000 cycles. Stability tests and surface morphology evaluations were conducted before and after cycling. A paired t-test (α = 0.05) was used to observe statistical differences. Results: The average retentive force of the MTPD was 6.86 ± 0.63 N and did not change significantly (p > 0.05) following the load cycles (6.66 ± 0.79 N). The MTPD demonstrated adequate stability under the occlusal load. Minimal deformations were observed on the magnet assemblies, keepers, ICs, and MTPD surfaces after the load tests. Conclusions: Considering the limitations of this study, an MTPD utilizing novel UTMAs fabricated through a digital workflow demonstrated adequate retentive force, stability, and durability for clinical use. Full article
(This article belongs to the Special Issue Digital Dentures: 2nd Edition)
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16 pages, 2143 KiB  
Article
Effect of a Polyhexanide-Based Antiseptic Composition on Dentin Microhardness and Mechanical Properties: An In Vitro Study
by Zurab Khabadze, Yulia Generalova and Oleg Mordanov
Materials 2025, 18(12), 2900; https://doi.org/10.3390/ma18122900 - 19 Jun 2025
Viewed by 416
Abstract
The effect of root canal irrigants on the mechanical properties of dentin is crucial in endodontic treatment planning. While antiseptics such as sodium hypochlorite and EDTA are widely used, their potential to weaken dentin structure remains a concern. Polyhexanide-based formulations may offer a [...] Read more.
The effect of root canal irrigants on the mechanical properties of dentin is crucial in endodontic treatment planning. While antiseptics such as sodium hypochlorite and EDTA are widely used, their potential to weaken dentin structure remains a concern. Polyhexanide-based formulations may offer a safer alternative. To assess the impact of a polyhexanide-based antiseptic composition, compared to standard irrigants, on the microhardness, Young’s modulus, and elastic deformation energy of dentin. Sixty extracted human teeth were sectioned and polished to prepare dentin samples. Baseline measurements of Vickers microhardness, Young’s modulus, and elastic deformation work were performed using a Microhardness Tester (CSM Instruments, Switzerland) with a Berkovich indenter. Samples were then divided into six groups (n = 10 per group) and exposed to different irrigants (NaCl 0.9%, NaOCl 3%, chlorhexidine 2%, EDTA 17%, and polyhexanide-based solutions—0.1% and 0.2% Lavasept). Post-treatment measurements were performed. Statistical analysis was conducted using non-parametric tests with Bonferroni correction. Sodium hypochlorite (3%) caused the most pronounced reduction in dentin microhardness and mechanical strength, though not always statistically significant. Polyhexanide-based solutions (0.1% and 0.2% Lavasept) showed a milder effect, with statistically significant changes observed only in elastic deformation energy for 0.2% polyhexanide. EDTA treatment led to severe surface destruction, precluding reliable post-treatment measurements. Polyhexanide-based irrigants demonstrated a more favorable impact on dentin mechanical properties compared to traditional irrigants, supporting their potential use in endodontic protocols aimed at preserving dentin integrity. Full article
(This article belongs to the Section Biomaterials)
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15 pages, 1281 KiB  
Article
Anterior Tooth Inclination Between Skeletal Class II and III Malocclusions After Surgical Orthodontic Treatment
by Hiromi Tomaru, Chie Tachiki, Yu Nakamura, Dai Ariizumi, Satoru Matsunaga, Keisuke Sugahara, Akira Watanabe, Akira Katakura and Yasushi Nishii
Diagnostics 2025, 15(12), 1553; https://doi.org/10.3390/diagnostics15121553 - 18 Jun 2025
Viewed by 444
Abstract
Background/Objectives: Anterior tooth inclination plays a critical role in treatment planning for surgical orthodontic cases. However, post-treatment outcomes in patients with jaw deformities often deviate from cephalometric values. This study aimed to compare anterior tooth inclination and skeletal morphology among patients with Class [...] Read more.
Background/Objectives: Anterior tooth inclination plays a critical role in treatment planning for surgical orthodontic cases. However, post-treatment outcomes in patients with jaw deformities often deviate from cephalometric values. This study aimed to compare anterior tooth inclination and skeletal morphology among patients with Class II and Class III malocclusions and to establish reference values for individualized treatment plans. Methods: A total of 122 patients (Class II: n = 40; Class III: n = 41; Class I: n = 41 as a control) were retrospectively analyzed. Cephalometric parameters, including U1 to FH and L1 to MP, were measured pre- and post-treatment. Group differences were analyzed using one-way ANOVA and Tukey’s multiple comparison test. Multiple regression analysis was used to establish prediction models for anterior tooth inclination. The threshold for statistical significance was set at p < 0.05. Results: Post-treatment, upper anterior teeth were more lingually inclined in Class II patients and more labially inclined in Class III patients compared to Class I controls (U1 to FH: Class II, 106.8°; Class III, 120.4°; Class I, 111.1°; p < 0.01). Lower anterior teeth were more lingually inclined in Class III patients compared to Class I patients (L1 to MP: 84.9°; p < 0.01). Regression models demonstrated good predictive value (R2 > 0.5) in non-extraction cases. Conclusions: Regression equations developed in this study, alongside the cephalometric averages of Class I individuals, may offer reliable reference values tailored to individual craniofacial morphology, contributing to optimized treatment planning in surgical orthodontic cases. Full article
(This article belongs to the Section Clinical Diagnosis and Prognosis)
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25 pages, 5958 KiB  
Article
Analysis of the Effect of Three-Dimensional Topology Modification on Temperature Field and Thermal Deformation of Internal Helical Gears Pair
by Gaowei Yao, Gang Liu, Jianxin Su, Hongbin Yang, Mingxuan Jin and Xiao Wei
Appl. Sci. 2025, 15(11), 6244; https://doi.org/10.3390/app15116244 - 1 Jun 2025
Viewed by 449
Abstract
The transmission accuracy and meshing performance of the gearbox is determined by the internal helical gears pair. Thermal deformation of internal helical gears pair is derived from sliding friction between the contacting teeth surface, resulting in shock, vibration, and misalignments. The purpose of [...] Read more.
The transmission accuracy and meshing performance of the gearbox is determined by the internal helical gears pair. Thermal deformation of internal helical gears pair is derived from sliding friction between the contacting teeth surface, resulting in shock, vibration, and misalignments. The purpose of this paper is to compare the influence of a modified gear and an unmodified gear on the temperature field and transmission characteristics of a planetary gear system under the same working conditions. This study presents an innovative temperature field model for gear pairs utilizing Surf152 elements, integrating Hertzian contact theory, tribological principles, and finite element analysis. For the first time, we quantitatively demonstrate the enhancement of thermo-mechanical performance through topological modification in helical gears. Under light-load conditions (200 rpm), the modified gear configuration exhibits a 6.38% reduction in tooth surface temperature and a 46.5% decrease in thermal deformation compared to conventional designs. Experimental validation confirms these improvements, showing an average 62.35% reduction in transmission error. These findings establish a novel methodology for high-precision gear design while providing critical theoretical foundations for planetary gear systems, ultimately leading to significant improvements in both transmission accuracy and operational lifespan. Full article
(This article belongs to the Section Applied Thermal Engineering)
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23 pages, 7331 KiB  
Article
Residual Film–Cotton Stubble–Nail Tooth Interaction Study Based on SPH-FEM Coupling in Residual Film Recycling
by Xuejun Zhang, Yangyang Shi, Jinshan Yan, Shuo Yang, Zhaoquan Hou and Huazhi Li
Agriculture 2025, 15(11), 1198; https://doi.org/10.3390/agriculture15111198 - 31 May 2025
Cited by 1 | Viewed by 438
Abstract
In the cotton fields in Xinjiang, residual film is present in the soil for a long period of time, leading to a decrease in the tensile strength of the residual film and increasing the difficulty of recycling. Existing technologies for residual film recovery [...] Read more.
In the cotton fields in Xinjiang, residual film is present in the soil for a long period of time, leading to a decrease in the tensile strength of the residual film and increasing the difficulty of recycling. Existing technologies for residual film recovery focus on mechanical properties and ignore the dragging and tearing of residual film by cotton stubble. The effect of cotton straw–root stubble on residual film recovery can only be better determined by appropriate machine operating parameters, which are essential to improving residual film recovery. Through analyses of the pickup device, key parameters were identified, and a model was built by combining the FEM and SPH algorithms to simulate the interaction of nail teeth, residual film, soil and root stubble. The simulation revealed the force change law of residual film in root stubble-containing soil and the influence of root stubble. By simulating the changes in the characteristics of the residual film during the process, the optimum operating parameters for the nail teeth were determined: a forward speed of 1849.57 mm/s, a rotational speed of 5.5 r/s and a soil penetration angle of 30°. Under these optimized conditions, the maximum shear strain, pickup height (maximum deformation) and average peak stress of the residual film were 1293, 363.81 mm and 3.42 MPa, respectively. Subsequently, field trials were conducted to verify the change in the impact of the nail teeth at the optimized speed on the recovery of residual film in plots containing root stubble. The results demonstrated that when the root stubble height was 5–8 cm, the residual film averaged a recovery rate of 89.59%, with a dragging rate of only 4.10% at crossings. In contrast, 8–14 cm stubble plots showed an 82.86% average recovery and an 11.91% dragging rate. In plots with a root stubble height of 5–8 cm, compared with plots with a root stubble height of 8–14 cm, the recovery rate increased by 6.73%, and the dragging rate of residual film on root stubble decreased by 7.81%. The percentage of entangled residual film out of the total unrecovered film was 30.10% lower in the 5–8 cm stubble plots than in the 8–14 cm stubble plots. It was confirmed that the effect of cotton root stubble on residual film recovery could be reduced under appropriate machine operating parameters. This provides strong support and a theoretical and practical basis for future research on the correlation between root stubble and residual film and how to improve the residual film recovery rate. Full article
(This article belongs to the Section Agricultural Technology)
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31 pages, 8398 KiB  
Article
Structural and Topological Optimization of a Novel Elephant Trunk Mechanism for Morphing Wing Applications
by Mir Hossein Negahban, Alexandre Hallonet, Marie Noupoussi Woumeni, Constance Nguyen and Ruxandra Mihaela Botez
Aerospace 2025, 12(5), 381; https://doi.org/10.3390/aerospace12050381 - 28 Apr 2025
Cited by 1 | Viewed by 545
Abstract
A novel mechanism for seamless morphing trailing edge flaps is presented in this paper. This bio-inspired morphing concept is derived from an elephant’s trunk and is called the Elephant Trunk Mechanism (ETM). The structural flexibility of an elephant’s trunk and its ability to [...] Read more.
A novel mechanism for seamless morphing trailing edge flaps is presented in this paper. This bio-inspired morphing concept is derived from an elephant’s trunk and is called the Elephant Trunk Mechanism (ETM). The structural flexibility of an elephant’s trunk and its ability to perform various types of deformations make it a promising choice in morphing technology for increasing the performance of continuous and smooth downward bending deformation at a trailing edge. This mechanism consists of a number of tooth-like elements attached to a solid wing box; the contractions of these tooth-like elements by external actuation forces change the trailing edge shape in the downwards direction. The main actuation forces are applied through wire ropes passing through tooth-like elements to generate the desired contractions on the flexible teeth. A static structural analysis using the Finite Element Method (FEM) is performed to examine this novel morphing concept and ensure its structural feasibility and stability. Topology optimization is also performed to find the optimum configuration with the objective of reducing the structural weight. The optimized mechanism is then attached to the flap section of a UAS-S45 wing. Finally, a skin analysis is performed to find its optimum skin material, which corresponds to the requirements of the morphing flap. The results of structural analysis and topology optimization reveal the reliability and stability of the proposed mechanism for application in the Seamless Morphing Trailing Edge (SMTE) flap. The optimization results led to significant improvements in the structural parameters, in addition to the desired weight reduction. The ETM maximum vertical displacement increased by 8.6%, while the von Mises stress decreased by 10.43%. Furthermore, the factor of safety improved from 1.3 to 1.5, thus indicating a safer design. The mass of the structure was reduced by 35.5%, achieving the primary goal of topology optimization. Full article
(This article belongs to the Special Issue Aircraft Design and System Optimization)
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30 pages, 8754 KiB  
Article
Multi-Objective Optimization of Gear Design of E-Axles to Improve Noise Emission and Load Distribution
by Luciano Cianciotta, Marco Cirelli and Pier Paolo Valentini
Machines 2025, 13(4), 330; https://doi.org/10.3390/machines13040330 - 17 Apr 2025
Viewed by 882
Abstract
This paper presents a comprehensive methodology to enable the optimization of an automotive electric axle to reduce noise emissions and improve load distribution. The proposed method consists of the application of two sequential optimization procedures. The first one focuses on the gears’ macro-geometry, [...] Read more.
This paper presents a comprehensive methodology to enable the optimization of an automotive electric axle to reduce noise emissions and improve load distribution. The proposed method consists of the application of two sequential optimization procedures. The first one focuses on the gears’ macro-geometry, based on an objective function that combines the contact ratio, power loss, and center distance. The second one optimizes the micro-geometry of the teeth to reduce the sound pressure generated by tooth impacts. Mechanical stress limits are considered as a constraint in the optimization process. Shafts, joints, and the electric motor are analyzed, taking into account their deformation that influences the dynamics of the entire system. The results of the proposed procedure are verified through experimental measurements and the comparison can be considered successful. Full article
(This article belongs to the Special Issue Advances in Vehicle Dynamics)
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14 pages, 1366 KiB  
Review
Minimally Invasive Access Cavities: A Benefit/Risk Analysis
by Marie Sevin, Edouard Orio and Anne-Margaux Collignon
J. Clin. Med. 2025, 14(7), 2476; https://doi.org/10.3390/jcm14072476 - 4 Apr 2025
Viewed by 1728
Abstract
Background/Objectives: Contemporary dentistry aims to preserve healthy tissues and perform minimally invasive procedures. The availability of ever-improving equipment allows practitioners to follow this conceptual innovation. This approach is also used in endodontics, as new types of access cavities seem to be gaining popularity, [...] Read more.
Background/Objectives: Contemporary dentistry aims to preserve healthy tissues and perform minimally invasive procedures. The availability of ever-improving equipment allows practitioners to follow this conceptual innovation. This approach is also used in endodontics, as new types of access cavities seem to be gaining popularity, allegedly reducing tissue destruction and loss of mechanical resistance of the treated teeth. Methods: We performed a comprehensive review of the available literature on the subject, focusing on in vitro studies accessible through major search engines and limiting the search to English-language articles published between 2010 and 2024. Results: Our analysis showed that the realization of reduced access cavities seems to preserve the mechanical resistance of the treated teeth, may compromise disinfection, and respects the original root canal path and the quality of obturation. In addition, these procedures appear to increase instrument deformation, fracture susceptibility, and treatment time: Mini-invasive cavities have many limitations and should only be used in situations where there is a high likelihood of success, where there are few difficulties and where sufficient material is available. However, with appropriate case selection, these new approaches can be used and should improve the prognosis of endodontically treated teeth. Full article
(This article belongs to the Section Dentistry, Oral Surgery and Oral Medicine)
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11 pages, 791 KiB  
Article
Fluoride in Drinking Water and Tea in the Arusha Region of Tanzania
by Sophia A. Bakar, Abigail Whitewood, Kathleen Glancey, Kara Okular, Alanna Bachtlin and David M. Kahler
Water 2025, 17(4), 546; https://doi.org/10.3390/w17040546 - 14 Feb 2025
Viewed by 1204
Abstract
High fluoride concentrations in drinking water affect millions of people around the world. The World Health Organization recommends a fluoride concentration in drinking water below 1.5 mg/L. Fluoride above this concentration can cause long-term problems known as fluorosis, such as mottled teeth and [...] Read more.
High fluoride concentrations in drinking water affect millions of people around the world. The World Health Organization recommends a fluoride concentration in drinking water below 1.5 mg/L. Fluoride above this concentration can cause long-term problems known as fluorosis, such as mottled teeth and increased risk of dental caries, or skeletal deformities. Rural communities near Arusha, Tanzania have high fluoride concentrations in their water; although, they typically consume even more tea. While tea has the benefit of disinfection by boiling, the tea leaves also impart additional fluoride; our tests with local water and tea show tea to increase fluoride from 3.2 to 6.4 mg/L. In the region, tea is traditionally prepared with milk. To better determine the total fluoride intake in the area, we measured tea prepared with and without milk. Tea infused with water and mixed with milk had 0.3 mg/L or 15% more fluoride compared to the fluoride from the constituents. Tea infused with water and milk had 0.8 mg/L or 40% less fluoride compared to the fluoride from the constituents. This apparent difference in fluoride is small, but the consistent difference from preparations warrants further investigation including reactions that may have caused less fluoride infusion or unknown interferences. Surveys also indicated that residents do not have water within 30 min of their residents, which places them into the Limited category for drinking water as defined by the Joint Monitoring Program. Full article
(This article belongs to the Section Water Quality and Contamination)
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9 pages, 3553 KiB  
Communication
Mechanical Efficacy Equivalence of W-Arch and Quad-Helix Orthodontic Arch Expansion Appliances: A Finite Element Study
by Aiko Kamoi, Yukiko Yokoi, Takuma Yoshida, Atsushi Otsuka and Norimasa Okafuji
Appl. Sci. 2025, 15(3), 1607; https://doi.org/10.3390/app15031607 - 5 Feb 2025
Viewed by 1659
Abstract
The quad-helix and W-arch are commonly used appliances for expanding the dental arch in orthodontic treatment. However, differences in performance between these two expanders remain unclear, and no guidelines exist for selecting one over the other. The purpose of this study was to [...] Read more.
The quad-helix and W-arch are commonly used appliances for expanding the dental arch in orthodontic treatment. However, differences in performance between these two expanders remain unclear, and no guidelines exist for selecting one over the other. The purpose of this study was to investigate whether there were differences in dental arch expanding ability between these appliances. Maxillary arch expansions were simulated using the finite element method. The expander was assumed to be an elastic beam, while the teeth and alveolar bone were treated as rigid bodies. The periodontal ligament (PDL) was modeled as a nonlinear elastic material. The teeth moved in the same direction as the initial movement caused by the elastic deformation of the PDL. The right and left canines, premolars, and first molars were expanded symmetrically in either parallel or fan shapes. When the wire diameter of the W-arch was set to 0.032 inches its stiffness became equivalent to that of a quad-helix with a wire diameter of 0.036 inches. Canines and premolars were expanded through tipping movements. The molars initially tipped buccally, then became upright and moved bodily. Both expanders expanded the arch in almost the same manner. There was no difference in arch expansion ability between the W-arch made of 0.032-inch wire and the quad-helix made of 0.036-inch wire. The W-arch may be preferred as the first choice due to its simpler structure compared to the quad-helix. Full article
(This article belongs to the Special Issue Trends and Prospects of Orthodontic Treatment)
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10 pages, 943 KiB  
Article
Exploring the Association Between Third Molar Agenesis and Carabelli Traits: A Cross-Sectional Study
by Isabela Ribeiro Madalena, Heloisa Guimarães Resende, Ariane Beatriz Blancato, Maria Angélica Hueb de Menezes-Oliveira, Flares Baratto-Filho, Poliana Ferreira Santos, Camila Paiva Perin, Thais Vilalba Paniagua Machado do Nascimento, Peter Proff, Christian Kirschneck, César Penazzo Lepri and Erika Calvano Küchler
Dent. J. 2025, 13(1), 23; https://doi.org/10.3390/dj13010023 - 6 Jan 2025
Cited by 1 | Viewed by 1438
Abstract
Background/Objectives: Dental agenesis is the congenital absence of at least one tooth and has been associated with several other developmental dental conditions, such as morphological dental alterations and Carabelli trait. This study sought to investigate whether third molar agenesis is associated with Carabelli [...] Read more.
Background/Objectives: Dental agenesis is the congenital absence of at least one tooth and has been associated with several other developmental dental conditions, such as morphological dental alterations and Carabelli trait. This study sought to investigate whether third molar agenesis is associated with Carabelli traits in permanent molars. Methods: This was a cross-sectional study that used a convenience sample obtained from the orthodontic records of German patients. Patients with syndromes, oral clefts, congenital alterations including dental agenesis (except agenesis of third molars), and severe cases of bruxism with a loss of tooth tissue were excluded. Teeth with cavitated lesions of dental caries, occlusal wear, restorations, and evident dental deformities were not included in the evaluation. The Carabelli trait was evaluated in the permanent maxillary molars. The Carabelli trait was classified according to its expression for each tooth as either absent, negative, and positive expressions. Third molar agenesis was evaluated only in patients older than 10 years old (based on when initial tooth formation should be visible in the panoramic radiographs). The two-sided Chi-squared test was used to investigate the association between the conditions, using an alpha of 5% (p < 0.05). Results: A total of 155 patients (74 females and 81 males) were investigated; 39 had third molar agenesis and 75 had the Carabelli trait. There was no statistical significance difference between patients with third molar agenesis and those with Carabelli traits in relation to sex (p > 0.05). The Carabelli trait was more common in first molars than in second molars. There was no statistical significant association between third molar agenesis and Carabelli traits (p > 0.05). Conclusions: Third molar agenesis was not associated with the Carabelli trait in the permanent molars in this population. Full article
(This article belongs to the Special Issue Dentistry in the 21st Century: Challenges and Opportunities)
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20 pages, 24379 KiB  
Article
Calculation Model for Multi-Roller Load Distribution of Planetary Threaded Roller Bearings Considering Machining Errors
by Zhijie Xie, Mingyang Li, Yicheng Hou, Zhiwei Wang and Kailiang Zhang
Machines 2025, 13(1), 26; https://doi.org/10.3390/machines13010026 - 3 Jan 2025
Viewed by 874
Abstract
Load-bearing capacity is critical in planetary threaded roller bearings (PTRBs). Machining errors cause uneven load distribution coefficients (LDC) among the rollers and the threaded teeth. The limited literature explores the influence of machining errors on PTRB’s load-bearing performance. A computational model that considers [...] Read more.
Load-bearing capacity is critical in planetary threaded roller bearings (PTRBs). Machining errors cause uneven load distribution coefficients (LDC) among the rollers and the threaded teeth. The limited literature explores the influence of machining errors on PTRB’s load-bearing performance. A computational model that considers multiple machining errors when determining the load distribution among the rollers and the threaded teeth is proposed in this paper. The PTRB is discretized into a multi-roller spring system. Moreover, a set of nonlinear equations is established based on deformation coordination and force balance. The theoretical model is verified against the finite element simulation results and previous studies. The influence of machining errors on the LDC among the rollers and the threaded teeth is investigated. Results indicate that pitch errors do not significantly impact the LDC among the rollers. However, pitch errors directly affect the LDC among the threaded teeth. Errors in roller nominal diameter and the eccentricity of the inner and outer ring axes cause uneven LDC among the rollers; axis misalignment has a complex effect on the LDC. The proposed computational model can guide the parameter design, component processing, and assembly method of PTRB. Full article
(This article belongs to the Section Advanced Manufacturing)
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18 pages, 17660 KiB  
Article
Simulation of an Orthodontic System Using the Lingual Technique Based on the Finite Element Method
by Abbas Hazem, Felicia Ileana Mărășescu, Mihaela Jana Țuculină, Dragoș Laurențiu Popa, Ionuț Daniel Geonea, Alexandru Iliescu, Petre Mărășescu, Ioan Ovidiu Gheorghe, Alma Roxana Pitru, Eugen Nicolae Tieranu and Ionela Teodora Dascălu
Diagnostics 2024, 14(24), 2832; https://doi.org/10.3390/diagnostics14242832 - 16 Dec 2024
Cited by 1 | Viewed by 1387
Abstract
Backgrounds/Objectives: The finite element method (FEM) is an advanced numerical technique that can be applied in orthodontics to study tooth movements, stresses, and deformations that occur during orthodontic treatment. It is also useful for simulating and visualizing the biomechanical behavior of teeth, tissues, [...] Read more.
Backgrounds/Objectives: The finite element method (FEM) is an advanced numerical technique that can be applied in orthodontics to study tooth movements, stresses, and deformations that occur during orthodontic treatment. It is also useful for simulating and visualizing the biomechanical behavior of teeth, tissues, and orthodontic appliances in various clinical scenarios. The objective of this research was to analyze the mechanical behavior of teeth, tissues, and orthodontic appliances in various clinical scenarios. Materials and Methods: For this study, we utilized a model derived from a set of CBCT scans of a 26-year-old female patient who underwent fixed orthodontic treatment using the lingual technique. Through a series of programs based on reverse engineering, we constructed a three-dimensional reconstruction of the teeth and their internal structures. Using the finite element method (FEM), we obtained six simulations of an orthodontic system utilizing the fixed lingual technique, in which we employed brackets made of chrome–nickel or gold, and archwires made of nitinol, gold, or stainless steel. Results: The study reveals that although the deformation of the archwires during orthodontic treatment is the same, the forces generated by the three types of archwires on brackets differ. The variation in forces applied to the brackets in the fixed lingual orthodontic technique is essential for customizing orthodontic treatment, as these forces must be precisely controlled to ensure effective tooth movement and prevent overloading of the dental structures. Conclusions: The FEM analysis allows for the identification of ideal combinations between the materials used for orthodontic archwires and the materials used for brackets. This ensures that the optimal intensity of forces applied during the fixed lingual orthodontic technique results in desired tooth movements without causing damage to the enamel, dentin, or pulp of the teeth. Full article
(This article belongs to the Special Issue Diagnostic Approach and Innovations in the Different Dentistry Fields)
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14 pages, 11435 KiB  
Article
Ischemic Risks Induced by Larger Orthodontic Forces on Dental Pulp and Neuro-Vascular Bundle in Reduced Periodontium
by Radu-Andrei Moga, Cristian Doru Olteanu and Ada Gabriela Delean
J. Clin. Med. 2024, 13(22), 6698; https://doi.org/10.3390/jcm13226698 - 7 Nov 2024
Viewed by 1089
Abstract
Background/Objectives: There are few data about the ischemic risks induced by the large orthodontic forces during periodontal breakdown in dental pulp and neuro-vascular bundle (NVB) and none on the individual tissular stress distribution, despite their great importance for orthodontic treatment planning. Our aim [...] Read more.
Background/Objectives: There are few data about the ischemic risks induced by the large orthodontic forces during periodontal breakdown in dental pulp and neuro-vascular bundle (NVB) and none on the individual tissular stress distribution, despite their great importance for orthodontic treatment planning. Our aim was to assess, by a numerical analysis, the biomechanical behavior of dental pulp and the NVB during a simulated horizontal periodontal breakdown (1–8 mm), under 2–4 N of applied orthodontic forces and five movements (rotation, translation, tipping, intrusion, and extrusion). Additionally, the ischemic and degenerative-resorptive risks were assessed. Methods: The analysis involved 72 3D models of nine patients, totaling 720 simulations. The models were CBCT-based, having the second lower premolar and surrounding periodontium, and they suffered 1 mm of gradual horizontal periodontal breakdown (up to 8 mm loss). Results: Both forces displayed a similar qualitative stress distribution in all five movements, but with a quantitative increase (doubling of stress amounts for 4 N when compared with 2 N). The highest amounts of stress were displayed at 8 mm of periodontal loss, which is lower than the 16 KPa of the maximum hydrostatic pressure. The NVB stress was higher than the pulpal stress. Rotation was the most stressful, closely followed by tipping, intrusion, and extrusion. Conclusions: A total of 4 N of applied force seems to not induce any ischemic or degenerative-resorptive risks for healthy intact teeth, in up to 8 mm of periodontal breakdown. Intrusion and extrusion determined the highest visible tissular deformation in the NVB, with potential ischemic and resorptive-generative risks for previously traumatized/injured teeth (i.e., occlusal trauma). Rotation and translation (in particular) showed the highest coronal and radicular pulpal stress with potential ischemic and resorptive-generative risks for previously injured/traumatized dental pulp (i.e., direct-indirect pulp capping). It seems that 4 mm of periodontal breakdown could signal a clinical stress increase with potential ischemic and degenerative-resorptive risks for the previously traumatized/injured tissues. Full article
(This article belongs to the Special Issue Clinical Research of Novel Therapeutic Approaches in Dentistry)
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