Search Results (301)

The characterization of ductile fracture in thin metallic sheets is challenging due to extensive plastic deformation and stable crack growth under plane-stress conditions. This study investigates the applicability of the load separation criterion as a single-specimen method for evaluating fracture behavior in thin aluminum sheets. Experimental tests were performed on double-edge-notched tension (DENT) specimens manufactured from a 1.2 mm thick commercial aluminum sheet with ligament lengths ranging from 4 to 20 mm. Load–displacement responses were analyzed using curve-fitting techniques to determine the separation parameter, geometry function, plastic η-factor, and the plastic component of the J-integral. The separation parameter stabilized in the plastic regime, and the geometry function followed a power-law relationship with the normalized ligament ratio, confirming the validity of the load separation assumption. The calculated fracture toughness values showed consistent averages of approximately 58–60 kJ/m² across different fitting approaches, which are in good agreement with the essential work of fracture (EWF) value of about 51.5 kJ/m² reported for the same material. These results demonstrate that the load separation approach provides a reliable and efficient framework for determining fracture parameters in thin ductile aluminum sheets using a single specimen. The methodology offers practical advantages for fracture assessment and structural integrity analysis of lightweight sheet structures in aerospace, automotive, and marine applications. Full article

In the field of oil and gas transportation, X80 pipelines are susceptible to localized plastic deformation caused by mechanical impact or geological activity. This leads to the formation of dents and the introduction of pre-strain, thereby affecting the structural integrity and fatigue life. This study systematically investigates the influence mechanism of pre-strain on the high-cycle fatigue performance of dented regions in X80 steel. Fatigue tests conducted across pre-strain levels of 1%, 2%, and 3% revealed that the induced plastic strain significantly degrades fatigue performance. Under constant stress amplitude, fatigue life decreases markedly with increasing pre-strain, a trend driven by the accumulation of micro-damage. Furthermore, a parametric P-S-N curve model that incorporates both pre-plastic strain and reliability was developed, providing a basis for quantitatively assessing the impact of pre-strain. By combining finite element analysis with the Smith-Watson-Topper (SWT) critical plane method, it was predicted that fatigue cracks in unconstrained dent primarily initiate at the dent periphery, with the critical plane orientation perpendicular to the circumferential direction, which aligns well with field observations. Parametric analysis indicates that the maximum operating pressure is the dominant factor affecting the fatigue life of the dented pipelines. This research elucidates the material-level fatigue failure characteristics of dented X80 pipelines and provides theoretical insights for life prediction and engineering protection. Full article

Electromagnetic attractive forming (EMAF), as an emerging branch of electromagnetic forming (EMF), has attracted increasing attention due to its unique capacity to shape workpieces toward the coil, offering distinct advantages in forming small-diameter tubes, repairing surface dents, and strengthening hole fasteners. This review systematically classifies and elaborates on the two main approaches for generating electromagnetic attractive force: (1) methods based on dual-frequency discharge and (2) methods based on low-frequency discharge. For each category, the working principles, key technological configurations, experimental verifications, and application scenarios are comprehensively discussed. The dual-frequency discharge approach, implemented through sequential dual-capacitor, dual-coil, and novel single-power circuits, enables controllable attractive forces for sheet/tube forming and hole-fastener strengthening. The low-frequency discharge approach, utilizing ferromagnetic effects, attractive screen, or current-phase-difference mechanisms, extends EMAF to ferromagnetic and non-ferromagnetic materials. Finally, the existing challenges and future research directions are outlined, aiming to provide clear research guidance for the in-depth development and practical engineering application of EMAF technology. Full article

Incorporating waste engine oil bottoms (WEOBs) as rejuvenators into reclaimed asphalt pavement offers a sustainable solution to reduce the consumption of non-renewable resources. To explore the effect of WEOBs on aged asphalt, WEOB-rejuvenated asphalt (WEOB-asphalt) with different thermal-oxidative aging times was prepared. Subsequently, viscosity, double-edge-notched tension (DENT), temperature sweep, linear amplitude sweep (LAS), and Fourier transform infrared spectroscopy (FTIR) tests were conducted to investigate the performance of WEOB-asphalt. The results indicate that WEOB-asphalt shows acceptable thermal-oxidative aging ability within 180 min. The WEOB-asphalt experiences a small decrease in critical crack tip opening displacement within a 180 min aging time. Additionally, the temperature sensitivity of WEOB-asphalt is low, and the rutting factors at temperatures of 46 °C and 52 °C can significantly distinguish the thermal-oxidative aging performance of asphalt at different aging degrees. The fatigue life of WEOB-asphalt decreases compared to the original asphalt after 540 min of aging when the strain exceeds 0.04%. Furthermore, WEOB-asphalt displays increased carbonyl and sulfoxide groups, indicating poorer thermal-oxidative aging resistance than the original asphalt. Based on these results, it is suggested that WEOB-asphalt should be used in areas with mild climate conditions to avoid its rapid secondary aging. Full article

Background: The shift toward precision orthodontics necessitates population-specific cephalometric databases. Reliance on Eurocentric norms for ethnically diverse populations—particularly underrepresented Middle Eastern groups—represents a significant evidence gap. This study establishes initial normative cephalometric data for Yemeni and Northern Turkish Cypriot (NTC) adults. Methods: This retrospective comparative study analyzed 400 lateral cephalograms from skeletal Class I adults (200 Yemeni and 200 NTC; age 18–40; gender-balanced). Twenty standardized parameters were assessed using VistaDent OC™ software (version 4.2.61, GAC Orthodontic Software solutions, Birmingham, AL, USA). Analyses included *t*-tests, MANOVA, effect size computations (Cohen’s *d*), and variance partitioning. The False Discovery Rate method controlled multiple comparisons. Results: Yemeni adults exhibited a more vertical facial growth pattern (indicated by a lower Jarabak ratio: 60.18 ± 4.50% vs. 65.79 ± 5.20%; *d* = 1.15) and pronounced soft-tissue convexity (N-A-Pog: 5.76 ± 1.20 mm vs. 3.82 ± 1.10 mm; *d* =1.69). NTC adults showed a mild skeletal Class II tendency (ANB: 4.51 ± 1.70° vs. 3.35 ± 1.50°; *d* = 0.72). Ethnicity accounted for 21.3% of craniofacial variance (partial η² = 0.213). Conclusions: This study provides foundational cephalometric reference data for two underrepresented populations. The significant morphological distinctions quantified here underscore the necessity of developing population-specific norms. These data should be considered as one component within comprehensive, individualized diagnostic frameworks in orthodontics, rather than standalone diagnostic criteria. Full article

This study examined the association between biofilm growth and surface properties of 3D printed, milled, and conventional materials used for manufacturing fixed dental prostheses. Disc-shaped specimens were produced and finished from five 3D-printing resins (VarseoSmile Crown plus [VSC], NextDent C&B MFH [ND], VarseoSmile Temp [VST], Temp PRINT [TP], P Pro Crown & Bridge [P]), two polymer milling blocks (composite: TetricCAD [TC], PMMA: TelioCAD [TEL]), two conventional polymer materials (Tetric EvoCeram [TEC], Protemp 4 [PT]), and zirconia (ZR). Surface roughness (R_a), wettability, interfacial tension (IFT) and surface topography were examined. Three-day biofilms were grown on the specimens using A. naeslundii, S. gordonii, S. mutans, S. oralis, and S. sanguinis in a multi-species suspension. Biofilms were quantified by crystal violet staining and with a plating and culture method (CFU/mL). Linear regression analysis was computed to demonstrate associations between the surface properties and biofilm growth. The strength of this relationship was quantified by calculating Spearman’s ρ. TC exhibited the highest, and TP the lowest IFT. TEC showed the highest R_a, while TEL had the lowest, with significant differences detected particularly between milled and 3D-printed specimens. TP specimens exhibited the highest biofilm mass, while ZR surfaces retained the least. Bacterial viability within the biofilms remained similar across all tested materials. There was a strong negative correlation between total IFT and biofilm mass, and a moderate positive correlation between R_a and CFU/mL. Surface properties are shaped by material composition, microstructure, and manufacturing methods and play a crucial role in biofilm formation on dental restorations. Full article

Studying surface energy and permeability offers insights into the relationship between temporary polymers and the oral environment. Variations in contact angle and surface free energy may signify modifications in surface polarity and tendency for plaque buildup, staining, or microcrack formation. Objectives: The present study aims to evaluate the influence of simulated salivary and chemical aging conditions on the surface and mechanical properties of 3D-printed PMMA provisional materials. Methods: Two 3D-printed polymethyl methacrylate (PMMA) resins were investigated, namely Anycubic White (Anycubic, Shenzhen, China) and NextDent Creo (NextDent, 3D Systems, Soesterberg, The Netherlands), using two aging protocols. Protocol A consisted of chemical aging in an alcohol-based mouthwash, while Protocol B involved thermal aging in artificial saliva. After aging, surface properties (wettability and SFE) and compressive behaviour were analyzed. Statistical analysis was conducted to assess the influence of temperature, immersion duration, and aging medium, with significance established at p < 0.05. Results: In Protocol A, mechanical properties showed a time-dependent decrease, with material-specific stabilization trends. In Protocol B, thermal aging resulted in elastic modulus reductions ranging from 35% to 46% relative to the reference. The yield strength exhibited similar tendencies. In Protocol A, X samples exhibited a consistent decline, while C samples stabilized after 14 days. For Protocol B, the fitted model produced residuals under 2%, confirming temperature as the primary variable. Conclusions: Chemical and thermal aging influence the physical and mechanical properties of the analyzed 3D-printed PMMA. Among the two protocols, thermal aging in artificial saliva resulted in more pronounced material degradation. After chemical aging in mouthwash, the surface free energy remained almost constant. After thermal aging, all samples demonstrated a gradual rise in SFE with prolonged immersion duration. The current study offers valuable insights into the environmental stability of printed PMMA; however, it is an in vitro evaluation. The findings indicate that temperature exposure and prolonged contact with oral hygiene products may affect the mechanical reliability of 3D-printed provisional restorations, which must be considered during material selection for longer temporary usage. Additionally, spectroscopic and microscopic analyses might better clarify the molecular-level chemical alterations linked to aging. Full article

Background/Objectives: The purpose of this in vitro study is to evaluate the effect varying palatal vault depths have on the accuracy of complete maxillary denture bases fabricated using additive manufacturing technology. Methods: One hundred complete maxillary denture bases were manufactured on two different digital light processing (DLP) dental 3D printers at five different palatal depths. After manufacturing, the denture bases were post-cured, scanned, and then analyzed in metrology software. Statistically significant differences were determined using two-way ANOVA tests for normally distributed data and the Kruskal–Wallis test for non-normally distributed data. Color deviation maps were used to give clinical relevance to the results. Results: Significant differences were found for both printers among some groups for the different palatal depths. In relation to the negative mean deviation, the data revealed that the NextDent printers were the least accurate (0.047 ± 0.004) in the group with the deepest palate. The positive mean deviation revealed the most deviation (0.077 ± 0.009) in the group with the deepest palate, which was also mirrored in the Asiga printer (0.050 ± 0.002). The color deviation maps revealed areas of positive and negative average deviation in all groups. The effect of the printer model (p = 0.007) and palatal depth (p = 0.04) on negative average deviation was significant. The effect of the interaction of printer and palatal depth was also significant (p = 0.001). Conclusion: Deeper palatal vaults are associated with higher deviation in DLP 3D-printed complete maxillary denture bases manufactured through additive manufacturing. Full article

Background/Objectives: Accurate drug dosage calculation in pediatric dentistry represents an essential component of everyday clinical practice. However, manual calculation methods, reliance on memory, and inconsistent pharmacological education often lead to uncertainty among practitioners. Methods: To support clinicians in this process, a mobile application—Dent.IN CALC—was developed as a rapid, evidence-based, and user-friendly tool. The app allows the input of age and weight to instantly generate recommended and maximum safe dosages of commonly prescribed antibiotics, analgesics, and local anesthetics. Additionally, it includes a list of corresponding pharmaceutical preparations available on the local market. A preliminary evaluation among sixty dentists revealed significant variability in dosage knowledge and confirmed the need for digital tools that facilitate accurate and efficient prescribing. Results: Most users rated the app as intuitive, time-saving, and highly beneficial for daily practice (mean satisfaction score 4.7 ± 0.4; 95% would recommend the app). Conclusions: The Dent.IN CALC app shows strong user acceptance and demonstrates how digital solutions can streamline workflow and support clinicians in routine pediatric pharmacological decision-making. Full article

Panoramic radiography remains a cornerstone diagnostic tool in dentistry; however, its two-dimensional nature limits the visualisation of complex maxillofacial anatomy. Three-dimensional reconstruction from single panoramic images addresses this limitation by computationally generating spatial representations without additional radiation exposure or expensive cone-beam computed tomography (CBCT) scans. This systematic review and conceptual study traces the evolution of 3D reconstruction approaches, from classical geometric and statistical shape models to modern artificial intelligence-based methods, including convolutional neural networks, generative adversarial networks, and neural implicit fields such as Occudent and NeBLa. Deep learning frameworks demonstrate superior accuracy in reconstructing dental and jaw structures compared to traditional techniques. Building on these advancements, this paper proposes HoloDent3D, a theoretical framework that combines AI-driven panoramic reconstruction with real-time holographic visualisation. The system enables interactive, radiation-free volumetric inspection for diagnosis, treatment planning, and patient education. Despite significant progress, persistent challenges include limited paired 2D–3D datasets, generalisation across anatomical variability, and clinical validation. Continued integration of multimodal data fusion, temporal modelling, and holographic visualisation is expected to accelerate the clinical translation of AI-based 3D reconstruction systems in digital dentistry. Full article

Structural deterioration inevitably leads to defects in buildings. It is primarily caused by environmental exposure, material ageing, and long-term service conditions, whereas defects such as poor soil compaction arise from improper construction practices rather than deterioration mechanisms. Major concrete defects include missing portions such as cracking, corrosion, dents, blemishes, and spalling. Failure to identify minor issues can lead to serious problems, which become more expensive and difficult to repair, as well as poorer overall building performance. Traditional structural assessment methods, such as visual inspections and non-destructive testing are typically used for periodic condition evaluation, whereas SHM involves continuous or long-term monitoring using sensor-based systems. However, such approaches can be manual, costly, dangerous, and biased. In order to overcome these limitations, contemporary SHM systems combine traditional approaches with building information modelling (BIM) and artificial intelligence (AI). Different AI algorithms are used, including SVM, random forest, regression, and KNN for machine learning and decision trees; random forest, K-means clustering, CNN, U-Net, ResNet, FCN, VGG16, and DeepLabv3+ for deep learning. This review will survey both the traditional and novel approaches in the field of SHM and the recent advancements. Full article

Additive manufacturing is increasingly integrated into dental technology, yet the mechanical performance of 3D-printed denture base resins remains strongly influenced by printing orientation and post-curing duration. This study evaluated the combined effect of three printing orientations (0°, 45°, 90°) and three post-curing times (30, 45, 60 min) on the flexural strength and surface microhardness of a denture base resin. Specimens designed in Blender and fabricated using NextDent Denture 3D+ resin were subjected to three-point bending tests (n = 5 per group) and Vickers microhardness measurements (n = 10 per group). One-way ANOVA assessed main and interaction effects. Printing orientation had a significant influence on flexural strength, with horizontally printed specimens exhibiting the highest values, whereas vertically printed specimens were consistently weaker. Post-curing time did not significantly affect flexural strength within any orientation. In contrast, microhardness increased progressively with longer post-curing durations, regardless of orientation, indicating continued surface polymerisation. Because flexural strength and hardness responded differently to curing duration, no single post-curing time was universally optimal; however, 0° printing consistently produced the strongest specimens for this resin–printer system. This trade-off is clinically relevant, because dentures require high flexural strength to resist fracture and sufficient hardness to minimise wear. Full article

Objectives: This in vitro study assessed the accuracy (trueness and precision) of different 3D-printed resin denture bases with 0°, 45°, and 90° printing orientations. Methods: Denture base was designed and fabricated using three 3D-printed denture base resins (DentaBASE, Denture 3D+, and FormLabs). Each resin was printed with its own printer and fabricated with different printing orientations, resulting in a total of 72 specimens (n = 8). Trueness and precision were evaluated before and after thermal aging using the superimposition method with best-fit alignment. The data were collected and analyzed using two-way ANOVA followed by post hoc Tukey’s test (α = 0.05). Results: The printing orientation significantly affected the trueness of 3D-printed resins (p < 0.001). The highest trueness was observed for NextDent at 0° printing orientation, while the lowest value was observed for ASIGA at 0° and 45° printing orientations. The precision of the denture base was significantly affected by different printing orientations for ASIGA (p = 0.006) and NextDent (p < 0.001) before thermal cycling, while the precision of FormLabs was significantly affected (p = 0.017) after thermal cycling. The highest precision was recorded for FormLabs at 45° printing orientation, while the lowest precision was observed for NextDent at 45° and 90° printing orientations. Moreover, the effect of thermal cycling on trueness was only significant for ASIGA at 0° printing orientation; however, the effect of thermal cycling on precision was significant for NextDent at 0° and 90° printing orientations. A 45° printing orientation provided the most accurate clinical fit. Conclusions: ASIGA showed the lowest trueness, while FormLabs exhibited the lowest precision, revealing performance differences between printers. Full article

Additive manufacturing (AM) offers precision and efficiency in occlusal splint fabrication; however, the combined influence of build orientation and post-curing duration on the mechanical performance of splint resins remains insufficiently explored. This in vitro experimental study evaluated the effects of three build orientations (0°, 45°, and 90°) and three post-curing protocols (uncured, standard, and extended) on the flexural strength (FS), flexural modulus (FM) and Vickers hardness number (VHN) of a Class IIa biocompatible occlusal splint resin (NextDent Ortho Rigid). A total of 180 specimens were fabricated using a vat polymerization-type 3D printing system. Statistical analyses were conducted using one-way analyses of variance and Tukey’s tests at a significance level of α = 0.05. Both build orientation and post-curing duration significantly affected FS and VHN (p < 0.001). The combination of 45° build orientations and extended post-curing produced the highest FS (169.76 MPa) and FM (7502.17 MPa), exceeding values typically reported for 3D-printed splints, while the 90° orientation with extended curing achieved the highest VHN (21.88). Hardness gains, however, plateaued beyond standard curing, indicating a trade-off between strength and surface hardness. These results demonstrate that print orientation and post-curing time are decisive parameters in optimizing the mechanical performance of 3D-printed occlusal splints. For high-load clinical applications such as bruxism, prioritizing flexural strength over surface hardness may improve appliance longevity, supporting 45° orientation with extended curing as an evidence-based manufacturing approach. Full article

This paper presents an integrated three-dimensional (3D) quality inspection system for mold manufacturing that addresses critical industrial constraints, including zero-shot generalization without retraining, complete decision traceability for regulatory compliance, and robustness under severe data shortages (<2% defect rate). Dual optical sensors (Photoneo MotionCam 3D and SICK Ruler) are integrated via affine transformation-based registration, followed by computer-aided design (CAD)-based classification using geometric feature matching to CAD specifications. Unsupervised defect detection combines density-based spatial clustering of applications with noise (DBSCAN) clustering, curvature analysis, and alpha shape boundary estimation to identify surface anomalies without labeled training data. Industrial validation on 38 product classes (3000 samples) yielded 99.00% classification accuracy and 99.12% macroscopic precision, outperforming Point-MAE (93.24%) trained under the same limited-data conditions. The CAD-based architecture enables immediate deployment via CAD reference registration, eliminating the five-day retraining cycle required for deep learning, essential for agile manufacturing. Processing time stability (0.47 s compared to 43.68 s for Point-MAE) ensures predictable production throughput. Defect detection achieved 98.00% accuracy on a synthetic validation dataset (scratches: 97.25% F1; dents: 98.15% F1). Full article