Search Results (578)

The thermal decomposition of DLP-printed green bodies containing a cross-linked 1,6-hexanediol diacrylate matrix filled with complex oxide powder of a cerium-activated garnet structure (GYAGG:Ce) was investigated. Non-isothermal thermogravimetric measurements were performed under an argon atmosphere at heating rates of 2, 4, 8 and 20 °C/min (four independent measurements for each heating rate). The main mass-loss stage occurs at approximately 350–470 °C. With the increase in the heating rate, the mean DTG peaks shift to a higher temperature: from 387.1 ± 10.3 °C at 2 °C/min to 427.9 ± 15.2 °C at 20 °C/min. The kinetics of thermal decomposition were investigated using isoconversional analysis methods. The apparent activation energy of the main mass-loss peak calculated by the Kissinger method was 200.85 kJ/mol (R² = 0.99). Gas-phase mass-spectrometric analysis tentatively assigned signals to water, CO, CO₂, and acrylate-derived fragments of organic chains. A thermal analysis-guided debinding schedule was developed and experimentally demonstrated, resulting in the production of bulk ceramics with measurable optical translucence (the full transmittance and in-line transmittance were 54.5% and 12%, respectively, for a sample 1.2 mm thick). The absence of large cracks and delamination was observed in both green and brown bodies by scanning electron microscopy. Full article

Two-dimensional (2D) materials offer opportunities for constructing functional devices; however, integrating them into macroscopic structures requires precise control over nanosheet dispersion, processing parameters, and structural design. This review summarizes research on the fabrication of 3D structures using nanosheet-based inks and composite feedstocks—including graphene and its derivatives, MXenes, transition metal dichalcogenides, hexagonal boron nitride, and black phosphorus. Studies indicate that material performance is determined by the combined effects of feedstock composition, printing conditions, structural design, and post-processing techniques. Direct Ink Writing (DIW) is a particularly suitable fabrication technique for various porous lattices and self-supporting structures where nanosheets form the primary functional network. High-concentration aqueous MXene inks and rheologically tuned graphene oxide-based inks serve as typical feedstocks, provided they exhibit favorable shear-thinning behavior, shape retention, and structural recovery capabilities. Regarding polymer-based composite components, Fused Deposition Modeling (FDM) is applicable to thermoplastic feedstocks loaded with 2D materials, whereas Stereolithography (SLA) and Digital Light Processing (DLP) utilize nanosheet-loaded photocurable resins to fabricate composites with intricate features, albeit with applications constrained by light attenuation and curing characteristics. Applications in sensing, energy storage devices, and biomedical scaffolds demonstrate the immense potential of these methods, while printed optoelectronic devices are discussed as a complementary case of device integration. Nevertheless, challenges such as material instability, trade-offs between resolution and scale, post-processing shrinkage, and incomplete biosafety assessments remain significant barriers to practical application, highlighting the need to develop reproducible processing techniques and conduct validation studies focused on real-world use. Full article

A polyurethane acrylate-based photosensitive resin system was developed for 405 nm DLP printing. The formulations were prepared by blending commercial urethane acrylate RT75A with TPO-L, BBOT, and one of four reactive diluents (ACMO, IBOMA, TPGDA, or CTFA). Double-bond conversion was determined by ATR-FTIR, whereas viscosity, UV–Vis transmittance, working-curve parameters (critical exposure and penetration depth), volumetric shrinkage, and mechanical properties were evaluated. The reactive diluent markedly affected both the liquid-state behavior of the resin formulations and the properties of the cured networks. RT75A-TP showed the highest double-bond conversion (97.9%) and volumetric shrinkage (4.65%). RT75A-CT exhibited the highest viscosity at 25 °C and the largest elongation at break (119 ± 9.5%). RT75A-IB exhibited the highest tensile strength (43.3 ± 3.1 MPa) and flexural strength (57.8 ± 1.1 MPa). All formulations maintained transmittance above 80% from 450 to 800 nm. A transparent aligner with a nominal thickness of 0.55 mm was directly printed from RT75A-IB, and its dimensional accuracy was evaluated by 3D scanning. Overall, the results show that reactive-diluent selection enables the coordinated tuning of DLP processability, double-bond conversion, optical performance, and mechanical behavior. Full article

Poly(ethylene glycol) diacrylate (PEGDA) has gained significant attention in biomedical research and 3D printing due to its biocompatibility, customizable mechanical properties, and ease of processing. Its acrylate functional groups facilitate UV-induced crosslinking and chemical modifications. This study produced and characterized PEGDA under 5 to 30 s curing times to assess its potential as a biomaterial. PEGDA was synthesized and confirmed using 1H-NMR and FTIR analysis, which showed that the material’s structure aligned with the existing literature. A 15% hydrogel solution was prepared using PEGDA, and curing times were adjusted using the DLP printer. FTIR analysis indicated the consumption of the terminal acrylate C=C groups, which is generally reflected by a decrease in the characteristic acrylate bands at approximately 1640 and 810 cm⁻¹ in the FTIR spectra. Compression tests revealed an increase in compressive strength from 14.08 kPa at 5 s to 53.48 kPa at 30 s. Additionally, after 5 s, the elastic modulus was measured at 42.23 kPa, and it increased to 160.44 kPa at 30 s, demonstrating an enhancement in the material’s stiffness. Numerical and theoretical natural frequencies increased, further supporting the role of curing time in material optimization. Finally, 30 s of curing exhibited more swelling and less degradation, confirming the role of curing time in controlling material behavior. These findings highlight PEGDA’s potential for biomaterial development in tissue engineering. Full article

Background: Post-curing may influence the properties of 3D-printed ceramic-filled resin restorations. This study compared four post-curing protocols for adaptation and microtensile bond strength (µTBS) of cemented, thermocycled DLP-printed inlays. Methods: Seventy-six maxillary premolars with standardised MOD cavities received inlays randomised (n = 19) to standard post-curing in air (SP), glycerine-immersed post-curing (GP), or SP plus microwave heating in glycerine (MG; 800 W nominal, 50 s) or autoclaving (AT; 121 °C). After cementation and 5000 thermocycles, adaptation discrepancy—a composite of post-curing change, seating, cement layer and ageing—was measured at 11 points by triple-scan superimposition before µTBS testing of the inlay–cement–dentine complex and failure-mode analysis. Results: Discrepancy (F(3, 37.6) = 24.47, p < 0.001) and µTBS (F(3, 39.8) = 6.09, p = 0.002) differed among protocols. MG showed the largest discrepancy (104.42 ± 13.57 µm; p < 0.01 versus all groups), lower µTBS than GP and SP (15.04 ± 5.13 versus 21.58 ± 4.35 and 20.19 ± 5.33 MPa) and predominantly adhesive failures (68.4% of teeth; interface unidentified). GP had the numerically lowest discrepancy (77.09 ± 5.48 µm), but its 7.7 µm difference from SP was within measurement uncertainty and not robust to sensitivity analysis. AT did not differ from SP. Conclusions: The complete MG protocol was associated with greater discrepancy and lower µTBS; GP did not differ robustly from SP. Full article

The success of temporary restorations depends on their marginal and internal adaptation, which are influenced by the manufacturing method. This study evaluated the intaglio surface accuracy, internal fit, and marginal fit of provisional crowns fabricated via subtractive (milling) and additive (3D printing) CAD/CAM technologies. Three milling systems—CEREC Primemill (4-axis), PrograMill Dry (5-axis), and Zirkonzahn M1 (5-axis)—and three 3D printers—Phrozen Mini 4K (LCD), SprintRay Pro95S (DLP), and Stratasys Objet30 (PolyJet)—were evaluated. For 3D printing, five build orientations (0°, 30°, 45°, 60°, and 90°) were tested. A total of 360 crowns were fabricated. Accuracy was quantified by Root Mean Square (RMS) deviation, and fit was assessed using the triple-scan method. Results indicated that build angles of 0° and 30° yielded the best performance for printed crowns (p < 0.05). While milling systems showed significantly superior intaglio accuracy and marginal fit compared to 3D printing (p < 0.05), no significant differences were found in internal fit between the two methods (p > 0.05). Milling offers higher dimensional predictability, but both approaches are clinically viable when optimized parameters are utilized. Full article

Background: Three-dimensional printing has enabled the development of customized materials with additional functional properties. This study evaluated a photopolymerizable resin (Bio Scaffolds1) functionalized with sodium fluoride (NaF) to determine fluoride release and assess the effects of NaF incorporation on the physicochemical, mechanical, and biological properties of the material and its potential use as a surface coating. Methods: Control and experimental groups containing 3 wt%, 5 wt%, and 7 wt% NaF were fabricated using digital light processing (DLP). The samples were characterized by flexural strength, contact angle, Fourier-transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, degree of conversion, fluoride release, and cytotoxicity in human gingival fibroblasts using the MTT assay. Results: The 3 wt% NaF group exhibited the highest flexural strength (29.017 ± 7.033), whereas NaF incorporation reduced the degree of conversion, particularly in the NaF5% Y NaF7% groups (43.38 %± 16.47%, 46.70 %± 14.49%). Spectroscopic and thermogravimetric analyses showed that the main features of the polymer matrix were retained after NaF incorporation, although concentration-dependent changes were also observed. Fluoride release increased with NaF concentration, reaching 32.44, 57.55, and 85.40 ppm after 28 d for the 3%, 5%, and 7% NaF groups, respectively. Throughout the 14-day evaluation, the NaF-containing formulations maintained MTT metabolic activity comparable to that of the unmodified resin control under the tested conditions. Conclusions: The NaF-functionalized resin successfully released fluoride while maintaining no cytotoxicity under the evaluated conditions. The 3% NaF formulation provided the best balance between mechanical strength and fluoride release. However, validation of coating formation and enamel protection is required before clinical translation. Full article

Effective bonding between zirconia ceramic restorations and resin remains a clinical challenge, particularly in the context of intraoral repair and cementation. This study aimed to investigate the micro-shear bond strength (μSBS) of stereolithography (SLA)- and digital light processing (DLP)-fabricated zirconia–resin cement-composite resin bonding specimens. Rectangular zirconia specimens (10 × 5 × 5 mm³) were fabricated by SLA, DLP, and computer numerical control (CNC) milling technologies. The surface roughness (Ra) of zirconia was measured after air abrasion. A composite resin cylinder (5 mm in height and 1 mm in diameter) was added to each zirconia substrate for the μSBS test. The failure mode images were obtained using a scanning electron microscope. The adhesive, cohesive, and mixed failure patterns were analyzed. The Ra and μSBS values were statistically analyzed with one-way ANOVA followed by S-N-K post hoc comparisons (a = 0.05). The Ra of SLA (1.05 ± 0.03 μm) and DLP (1.02 ± 0.03 μm) zirconia after air-abrasion were significantly higher than that of CNC (0.91 ± 0.02 μm) (p < 0.001). The SLA (23.37 ± 4.66 MPa) and DLP (23.24 ± 3.7 MPa) groups exhibited similar μSBS values for the bonding specimens to those of the CNC group (21.13 ± 3.48 MPa) (p = 0.237), indicating that the bond strength of the zirconia–resin cement-composite resin assembly for SLA and DLP zirconia was comparable to that for CNC zirconia. Full article

Breast-conserving surgery (BCS) requires accurate intraoperative localization of the tumor, which moves between the prone diagnostic and supine surgical positions. We present a projector-based augmented-reality (AR) localization system that projects a crosshair directly onto the patient’s skin at the predicted tumor location. The pipeline combines rigid registration of ceramic fiducials between prone and supine CT (tumor error 0.30 mm on a real phantom), a SOFA finite-element simulation of gravity-driven prone-to-supine soft-tissue deformation (mean bead displacement 24.7 mm on a synthetic mesh; not validated on a deformable phantom), two-stage ICP surface alignment (RMSE 0.92 mm on a simulated camera; not yet validated on real D415 acquisitions), and projector–camera (ProCam) extrinsic calibration driving the crosshair projection. Because the tumor and sub-surface fiducials are not visible in the live RGB-D scene, a direct non-circular in vivo target registration error (TRE) on the tumor cannot be measured in the present phantom configuration. We instead report a component-based end-to-end error budget obtained as the root-sum-square of three independently measured component errors: 2.7 mm (RSS planning estimate, not a directly measured end-to-end accuracy) —rigid CT 0.30 mm, ProCam physical projection 2.50 mm, ICP 0.92 mm. The ProCam term is largest but sub-3 mm. The Gray-code reprojection residual (~11 mm in 15-pose recalibration; 8.62 mm in the deployed 4-pose calibration) overestimates the actual projection error by ~4× (resp. ~3.4×): least-squares calibration averages the consumer-DLP vertical quantization (16-level Gray-code decode on XPR-DLP) into an accurate rigid transform, so the per-observation residual reflects observation quantization, not projection accuracy. The quantization’s measurable cost is projection variance (max 5.5 mm), which motivates phase-shifting structured light. Boundary conditions on phantom rigidity, sub-surface fiducials, and simulated-camera ICP are stated explicitly. Full article

This article presents an analysis of the effect of an anti-reflective layer on the measurement process using the 3D GOM (ATOS II Triple Scan; currently ZEISS) optical scanner for spherical elements manufactured using four additive methods: PolyJet Modeling (PJM), Digital Light Processing (DLP), Melted Extrusion Modeling (MEM), and Direct Metal Laser Sintering (DMLS). The research focused on analyzing the effect of the anti-reflective (AR) layer on changes in numerical data and on differences that define the shape of the measured elements. It was noted that models made of light-cured resin (EC100 (DLP) and RGD720 (PJM)) were characterized by AR layer absorption, which affected the measurement results. The use of the AR layer also increases the number of points for which a fitted sphere is created in the optical scanner software for shape analysis of the research models. The application of the AR layer also affects the average dimensional deviations (relative to the MB1 and MB2 research models), most significantly for models made using the PJM and MEM methods (approx. 0.02 mm), and least significantly for models made using the DMLS method (approx. 0.004 mm). The conducted research, presented measurement results, analyses, and conclusions, will help predict the impact of using the AR layer on the measurement process and the accuracy of the obtained results of measured geometric parameters during 3D GOM (ATOS II Triple Scan) optical measurements of models made of selected materials. Full article

The long-term storage stability of photocurable alumina suspensions is a critical factor in Digital Light Processing (DLP), yet conventional sedimentation tests provide only limited information about future changes in suspension behavior. This work evaluates analytical centrifugation (LUMiSizer) as a rapid tool for assessing the stability of alumina suspensions stabilized with Disperbyk-103 and Disperbyk-111 dispersants. Rheological measurements, aging tests, and characterization of sintered specimens showed that suspensions with lower instability indices exhibited significantly smaller changes during storage and yielded more reproducible properties after sintering. In particular, the Disperbyk-111 system remained largely unchanged after 20 days of storage, whereas the Disperbyk-103 suspension underwent pronounced rheological aging accompanied by lower density and greater shrinkage after sintering. The results indicate that the instability index obtained by analytical centrifugation provides a useful screening indicator of suspension stability during storage and may serve as a practical tool for selecting dispersant formulations for DLP-based ceramic processing. Full article

Photocrosslinked gelatin methacryloyl/methacrylated chitosan (GelMA/CSMA) hydrogels are attractive for biomedical applications but are limited by insufficient mechanical strength. Here, γ-methacryloxypropyltrimethoxysilane (MPTS) was prehydrolyzed and condensed to generate siloxane species retaining polymerizable methacrylate groups, which were subsequently incorporated into the GelMA/CSMA network as a reinforcing phase. The effects of MPTS precursor concentration (2–5% w/v) and prehydrolysis time (12–48 h) on the morphology, viscoelasticity, compressive behavior, cytocompatibility, and DLP printability of the resulting GCM hydrogels were systematically investigated. FTIR confirmed methoxy-group consumption while retaining C=C functionality. SEM showed that increasing MPTS precursor concentration increased the apparent abundance of granular features, whereas prolonged prehydrolysis produced larger structures. XRD indicated a predominantly amorphous MPTS-derived phase. GCM-48 h-5% achieved a storage modulus of 23.5 kPa, compressive modulus of 0.682 MPa, and maximum compressive stress of 1.081 MPa, corresponding to 7.4-, 16.9-, and 4.0-fold increases over the GelMA/CSMA control, respectively. The hydrogels exhibited favorable L929 cytocompatibility and retained DLP printability under 405 nm irradiation. These findings demonstrate that regulating MPTS precursor concentration and prehydrolysis time provides a simple route to mechanically reinforce DLP-printable GelMA/CSMA hydrogels without directly incorporating preformed silica particles. Full article

Additive manufacturing (AM) can support more sustainable polymer production, but the benefit is conditional on process energy, material chemistry, build yield, post-processing, service life, repair, and end-of-life recovery. This critical integrative review compares three polymer AM routes: stereolithography (SLA), digital light processing (DLP), and fused deposition modelling (FDM) through two deliberately contrasting application scales: pallet-scale load-bearing structures and membrane feed spacers. The review distinguishes direct application evidence from design opportunities inferred from adjacent AM literature. For pallet-scale structures, the literature currently supports large-format thermoplastic extrusion, zoned cellular architectures, modular repair, and controlled recycled feedstock as plausible translation routes, but direct peer-reviewed evidence for fully additively manufactured transportation pallets remains very limited. For membrane feed spacers, direct studies provide stronger quantitative evidence: published 3D-printed designs have reported approximately threefold pressure-drop reduction with doubled specific water flux, pressure-drop gradients as low as 0.091 bar m⁻¹ under reported test conditions, and a 16% increase in permeate flux with a thinner fouling layer for a honeycomb geometry. Process-energy evidence also shows that results depend strongly on the functional unit and machine state; reported desktop values span 24.8–85.7 kJ cm⁻³ for FFF and 10.8–21.5 kJ cm⁻³ for SLA, while post-processing and machine utilization can materially change the lifecycle result. Recycled polymers likewise involve a performance–circularity trade-off: some post-consumer PLA studies report strength losses of about one-third or more, whereas controlled blends and recycling strategies can retain a much larger fraction of virgin-material performance. The synthesis therefore treats geometry, process parameters, material state, operational performance, lifecycle impact, and cost as one coupled design problem rather than assuming that AM, recycled content, or bio-based chemistry is inherently sustainable. Full article

Microbial contamination remains a major challenge in food systems, creating demand for stable natural antimicrobials. This study investigates the inducible antibacterial response of Hermetia illucens and characterized the black soldier fly defensin-like peptide DLP4. Larvae were challenged with Staphylococcus aureus or Escherichia coli, and hemolymph activity, antimicrobial-peptide gene expression, C18 solid-phase extraction fractions, and LC–MS/MS profiles were evaluated. Synthetic mature DLP4 was further assessed for antibacterial spectrum, physicochemical stability, and structural properties. Hemolymph antibacterial activity varied with treatment and time, while DLP4 and CLP1 showed distinct transcriptional responses. Antibacterial activity was concentrated in early fractions, with F3 showing the greatest activity. LC–MS/MS detected a conserved DLP-family motif and a cysteine-rich defensin-like peptide in F3, whereas the complete 40-amino-acid sequence of synthetic DLP4 was confirmed. DLP4 showed strong, strain-dependent activity against Gram-positive bacteria, including Bacillus subtilis, Listeria ivanovii, and Staphylococcus spp., while no MIC endpoint was detected for the tested E. coli strains. DLP4 retained substantial activity after heat, ultraviolet, storage, pH, NaCl, and most metal-ion treatments, although Fe³⁺ reduced activity. These findings support DLP4 as a stable, Gram-positive-active antimicrobial candidate for further evaluation in food systems. Full article

Objective: This study aims to investigate whether combining automated tube voltage selection (ATVS) with P3T for contrast injection in coronary computed tomography angiography (CCTA) allows for patient-tailored scanning protocols. Specifically, we assessed whether this combination maintains equivalent image quality and adequate diagnostic image quality. Methods: This retrospective study included 378 patients who underwent CCTA using ATVS and P3T technologies. We divided the patients into three groups based on the scanning tube voltage: 70-, 80-, and 90-kV groups. Furthermore, each group was divided into sequence and spiral scanning subgroups based on the acquisition method. The CM injection volume and rate, volume CT dose index (CTDIvol), and dose–length product (DLP) were recorded. The CT value of the enhanced coronary artery, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated by artery segment. Image quality was evaluated using a four-point grading scale in a double-blind manner. Results: The SNR did not differ among the groups in any segments (p > 0.05). And the subjective image quality showed only minor differences among the groups. The body weight, which determines ATVS and P3T protocol algorithm, is positively correlated with the automatic tube voltage, CM injection volume, and effective radiation dose. Furthermore, when using the same tube voltage under the combined ATVS and P3T protocols, sequence scanning yielded a lower radiation dose than spiral scanning (p < 0.05). Conclusions: CCTA combining ATVS and P3T technology enables individualized scanning protocols while maintaining adequate diagnostic image quality. Full article