To compare the wear, fracture strength, and reliability of definitive resin three-unit fixed dental prostheses (FDPs) additively manufactured (AM) with different technologies to those subtractively manufactured (SM) from a high-impact polymer composite (HIPC). Thirty-two three-unit posterior FDPs (1-mm chamfer finish line, connector cross-sectional area: 16 mm2, minimum occlusal thickness: 1 mm, cement space: 100 µm) were either AM from a resin for definitive use (VarseoSmile Triniq) using digital light processing (AM-DLP), low force display (AM-LFD), or liquid crystal display (AM-LCD) technologies, or SM from a HIPC (SM-HIPC) (n = 8). All FDPs replaced the right second premolar. All FDPs were scanned before and after thermomechanical aging and subjected to load-to-fracture testing. Pre- and post-aging scans were digitally assessed for maximum wear depth and volume loss. Wear and fracture data were analyzed using one-way analysis of variance and Tukey tests, while chi-squared tests were used to evaluate Weibull parameters (α = 0.05). Mean fracture loads ranged from 1013 to 2725 N, while mean characteristic strength values ranged from 1072 to 2895 N. SM-HIPC mostly had lower wear (P ≤ 0.018), and AM-DLP had lower volume loss than AM-LFD and AM-LCD (P < 0.001). SM-HIPC showed the highest fracture load and characteristic strength, while AM-LFD had higher fracture load and characteristic strength than AM-LCD (P ≤ 0.001). SM-HIPC demonstrated better wear resistance along with the highest fracture and characteristic strength. Among AM FDPs, AM-DLP showed the lowest volume loss, while AM-LFD withstood higher loads and exhibited greater characteristic strength than AM-LCD. Three-unit FDPs fabricated with tested AM resin and digital light processing or low force display technologies may be suitable alternatives to those in high-impact polymer composite considering the reported masticatory forces of the molar region (1110 N). Nevertheless, they might also be more prone to complications related to wear.

Zirconium silicate (ZrSiO 4 ) is a low-cost and widely available ceramic material with excellent thermal properties. Its poor sinterability as a refractory material requires special attention in the forming and sintering methods, as well as the use of additives to favour its densification. In this work, Al 2 O 3 nanoparticle additions to zircon-based materials are used to form reinforcing crystallographic phases, such as mullite and t-ZrO 2 , by reaction sintering. It is revealed that this process is dependent on the powder shaping method. The effect of slip casting and additive manufacturing using digital light processing on the microstructure, composition and spatial disposition of the new formed crystalline phases is reported. For each shaping technique, the suspension and shaping process parameters have been optimized prior to conventional sintering and characterization of the final parts.

Additively manufactured structured perovskite/Al2O3 monolithic catalysts by digital light processing: design and application for CO2 methanation

Biomimetic villi-crypt scaffold-on-chip with tunable mechanical properties for intestinal epithelium modeling.

High-yield cell-derived extracellular matrix bioink via macromolecular crowding for versatile 3D bioprinting.

A degradable PEGDA-dopamine hydrogel with ROS scavenging capacity supports flexible design for nerve repair.

The photoinitiating system is a decisive factor governing the speed, resolution, and operational robustness of digital light processing (DLP) 3D printing. However, most existing systems rely on inert atmospheres, high irradiation intensities, or prolonged exposure times, severely limiting printing efficiency and practical applicability. Here we report a molecular design paradigm that fundamentally redefines the functional role of multiple-resonance thermally activated delayed fluorescence (MR-TADF) materials, transforming them from efficient light emitters into highly active triplet photocatalysts through selenium-atom engineering. By integrating carbonyl-assisted n-π*/π-π* state coupling with selenium-induced spin-orbit enhancement, the resulting photocatalyst QPSO achieves a near-unity intersystem crossing quantum yield together with an exceptionally large forward-to-reverse intersystem crossing rate constant ratio, thus efficiently channeling exciton flux into long-lived, redox-active triplet states. When combined with a hypervalent iodonium co-initiator, this system enables rapid photopolymerization in ambient air using low-intensity blue light. As a result, single-layer curing is completed within only 1.5-2s across a broad thickness range, affording a printing resolution down to 10µm and a record-high build speed of up to 72cm h-1 at 400µm layer thickness. The platform supports the fabrication of complex hierarchical architectures while exhibiting excellent biocompatibility.

Visible-light-driven polymerization offers unparalleled spatiotemporal control and energy efficiency, yet its practical performance is fundamentally constrained by the excited-state dynamics of the photosensitizer. In this study, we report a class of ortho-positioned multi-donor-acceptor molecules featuring multichannel through-space charge transfer (TSCT) characteristics as highly efficient, heavy-atom-free triplet photosensitizers. By constructing a highly twisted three-dimensional (3D) charge-transfer network, these molecules achieve exceptional photophysical performance, including high intersystem crossing (ISC) quantum yields (ΦISC up to 0.86), microsecond-scale triplet lifetimes, and an extraordinarily small singlet-triplet energy gap (ΔEST as low as 0.008eV), while maintaining high triplet energies and strong visible-light absorption. Benefiting from these attributes, the TSCT photosensitizers efficiently activate diphenyl ketone benzoyl oxime ester coinitiators via a triplet-triplet energy transfer (TTEnT) mechanism, enabling rapid and well-controlled acrylate polymerization under low-intensity visible-light irradiation. Importantly, this strategy enables, for the first time, the application of multichannel TSCT photosensitizers in digital light processing (DLP) 3D printing, allowing high-resolution fabrication of complex 3D architectures under ambient conditions with excellent operational robustness and biocompatibility. This work establishes a versatile molecular platform for the rational design of organic triplet photosensitizers and advances visible-light-based precision manufacturing technologies.

This study determined the influence of post-curing protocols on the color stability of provisional and long-term 3D-printable resin composites. Disc-shaped specimens were fabricated from a provisional (Prov) and long-term (Crown) 3D-printable resin composites using a digital light processing printer. Post-curing protocols included exposure to 405nm-based light sources (Anycubic for 30 or 60min in the standard mode or Procure 1) and one 385nm-based light source (Procure 2 with distinct protocols). Color parameters (L*, a*, b*) were measured at baseline, after 14 and 21 d of dry storage, and after 7 d of water immersion. Post-curing protocol, material, and storage condition significantly influenced color stability. High-irradiance protocols resulted in the highest color change values, exceeding the clinical acceptability threshold (ΔE00>1.8). Water immersion induced a significant whitening effect and increased total color change in all groups. The long-term resin demonstrated superior color stability compared to the provisional one across all post-curing protocols. The choice of post-curing protocol is critical for aesthetic performance, as high-irradiance parameters, while potentially beneficial for mechanical properties, can compromise chromatic stability, particularly in materials with low filler content.

Fabrication and biocompatibility evaluation of 3D printed tablets using Digital Light Processing (DLP) printing for the controlled release of ketoprofen.

Biomimetic bone-matching DLP-printed gradient TPMS ceramic implants.

Bioelectric ink bridge: An electroactive casein bioink for cartilage regeneration by actively restoring the electrophysiological niche.

This chapter provides a detailed, step-by-step protocol for the fabrication of architecturally defined brain organoid-like neural microtissues using a sequential digital light processing (DLP) bioprinting strategy. The method relies exclusively on DLP technology to fabricate complex heterogeneous structures through a layer-by-layer vat-switching technique. Central to this protocol is the formulation of a nanocomposite bioink, where reduced graphene oxide (rGO) nanoparticles and bacterial cellulose are mixed with gelatin methacryloyl (GelMA) matrix. This composition provides enhanced electrical conductivity, printability, and mechanical stability, promoting neural network maturation. We describe the complete workflow from induced pluripotent stem cell (iPSC) culture and neural induction, through bioink preparation and DLP printing parameter optimization, to long-term static culture and functional validation. This protocol addresses key limitations of conventional self-assembly methods, offering improved reproducibility, structural control, and physiological relevance for modeling neurodevelopment and disease.

Principle-based multiphysics simulation for 3D bioprinting systems: modelling inkjet, extrusion, and DLP processes.

This work features a dataset intended to aid in the development of processing parameters for particulate composite materials for additive manufacturing (AM) using digital light processing (DLP) method. Hollow glass microspheres (HGMs) are used as particulate fillers to manufacture syntactic foam composites. The standard thermosetting resins have a recommended set of 3D printing parameters. However, when the particles are mixed to 3D print composites, the mixture properties change, and the processing parameters need to be adjusted according to the particle volume fraction, size and other parameters. This dataset provides rheological measurements on the neat resin and resin-HGM composite mixtures intended for vat photopolymerization (VP) based DLP method. Three HGM density grades (0.13, 0.23, and 0.31 g/cm³ true particle densities) were examined at 10, 20, and 40 vol.% to capture the effects of particle density and volume fraction on resin flow behavior. Viscosity was measured using an Anton Paar MCR702 analyzer at a range of shear rates (1-50 s⁻¹) and temperatures (35-125 °C), generating 50 independent data files for 5 trials repeated for each of the 10 compositions. The dataset records the coupled influence of temperature and shear rate for each composition, providing a foundation for modeling viscosity-shear rate-temperature-composition relationships. Interpolations of various parameters at a benchmark viscosity of 0.40 Pa·s enable extraction of processing windows relevant to VP of the composite mixtures and significantly reduce the trial and error involved in processing parameter optimization for composite mixtures. The dataset also includes µCT image stacks for representative specimens, supporting qualitative assessment of particle dispersion and internal structure.

Digital fit and positional trueness analysis of a crown seated on additively manufactured casts fabricated using different manufacturing trinomials and build orientations.

Polychloroprene is a foundational high-performance synthetic elastomer known for its exceptional chemical stability, resistance, and mechanical properties, making it useful in many important applications ranging from aerospace seals to medical devices. Despite its widespread use, polychloroprene is almost exclusively processed by using thermal cure agents. Herein, we report the first-ever successful ultraviolet (UV) curing and three-dimensional (3D) printing of polychloroprene networks. Leveraging thiol-ene click chemistry, solid polychloroprene was dissolved in a solvent and UV-cured with varied concentrations and architectures of thiol cross-linkers. Upon solvent evaporation, the resulting cross-linked polychloroprene networks exhibit ultrahigh extensibility, with strain at break values approaching 2000%. Significantly, their thermal properties show only marginal differences from those of the uncured material, confirming the preservation of the intrinsic polychloroprene characteristics. We demonstrate the potential of this new material platform using photorheology experiments, as well as successful 3D printing of complex objects using a commercial digital light processing (DLP) system. The printed articles exhibit mechanical properties fully comparable to conventionally processed, unfilled polychloroprene rubber, achieving an ultimate tensile stress of 2.4 MPa and a strain at break of 1200%. This work overcomes a significant processing barrier, offering an avenue to additively manufacture high-performance polychloroprene structures with exceptional mechanical resilience.

The potential of soft actuators for tasks in complex environments remains constrained by their lack of real-time proprioceptive capabilities. Here, this challenge is addressed through a multimaterial digital light processing (DLP) 3D printing strategy for constructing bilayer actuators integrating thermoresponsive actuation with strain-sensing functions. Two photocurable functional inks were developed and integrated into a single heterogeneous bilayer system via multimaterial DLP 3D printing. The passive layer consists of a dual-network ionoelastomer based on a polymerizable deep eutectic solvent (PDES) and carboxymethyl cellulose (CMC), with favorable mechanical properties (tensile strength ∼0.5 MPa) and sensitive strain-sensing performance (gauge factor = 2.11). The active layer is composed of a functionalized poly(N-isopropylacrylamide) hydrogel; the incorporation of a DES synergistically enhanced its mechanical performance (compressive strength ∼1.05 MPa) while enabling effective regulation of the lower critical solution temperature (LCST: 32-46 °C). Seamless integration and robust interfacial bonding between these heterogeneous materials were achieved by systematically optimizing the printing process. The resulting bilayer actuators demonstrated efficient and tunable thermoresponsive actuation, with programmable complex deformations realized through the structural design of the active layer. Furthermore, the integrated sensing capabilities enabled self-perception, allowing the actuator to monitor its own deformation states during actuation. This multimaterial DLP 3D printing strategy established a material and processing foundation for the construction of intelligent soft systems with proprioceptive capabilities.

Active composites (ACs) capable of autonomous shape transformation under external stimuli enable new opportunities for soft robotics, biomedical devices, and intelligent structures. However, the combinatorial design space of multi-material 3D printing makes inverse design computationally intractable. Here, a reinforcement learning (RL)-based framework is proposed that reformulates the inverse design of thermally active composites (TACs) as a sequential decision-making process. A 4 × 24 grid is decomposed into 24 column-wise decisions to minimize deformation error with respect to target trajectories. A single target design was first demonstrated for an individual trajectory. A target-conditioned policy was then learned using multiple targets to enable rapid design across diverse shapes. The multiple target policy was further transferred to accelerate single target optimization. Performance was evaluated against genetic algorithm (GA) and sequential subdomain optimization (SSO) using the number of samples and function evaluations (FEs) under identical termination criteria. Experimental validation was conducted using 4D-printed TAC specimens via grayscale digital light processing (g-DLP), and demonstrations with complex trajectories, including free-form KAIST logo patterns, confirm that the proposed framework achieves target accuracy (root mean square error ≤ 0.1) with low samples and FEs. This study demonstrates that an RL agent can rapidly perform sequential material design through long-term reward optimization, indicating its potential for extension to intelligent design and manufacturing pipelines.

The purpose of this in vitro study was to evaluate the mechanical performance, dimensional accuracy, and bonding behavior of fused filament fabrication (FFF)-printed provisional restorations made from polymethyl methacrylate (PMMA) and polyethylene terephthalate (PET), and compare them with digital light processing (DLP)-printed and computer-aided numerical control (CNC)-milled ones. Occlusal veneers (OV), posterior crowns (PC), and anterior crowns (AC) (n = 30) were fabricated using FFF (PMMA, PET), DLP (acrylate), and CNC (PMMA) to assess initial fracture load (IFL). To determine reproducibility three restorations of each group were scanned and compared with each other; to determine printing accuracy the scanned restorations were compared with the STL generated for manufacturing. For shear bond strength (SBS) testing, 72 PMMA (FFF) specimens were conditioned with either Monobond Plus (MP) or Visiolink (VL) and bonded with acrylic cylinders using a dual-cure luting composite (Variolink Esthetic DC). Half of each group underwent thermocycling (10,000 cycles, 5 °C/55 °C, 30 s dwell time); the remainder was tested initially. Additionally, 48 FFF-printed PC were fabricated from PET and PMMA to investigate the fracture load in relation to the adhesive material (FL). PMMA crowns were conditioned with MP (n = 16) or VL (n = 16) and bonded with Variolink Esthetic DC. PET crowns were cemented with either Meron (ME) or Ketac Cem Plus (KE). Half of the PMMA and all PET crowns were subjected to masticatory simulation (1,200,000 cycles, 5 N, 5 °C/55 °C, 60 s dwell). Data were analyzed using Kolmogorov–Smirnov, Kruskal–Wallis, and Mann–Whitney U tests, including IFL, SBS and FL parametric tests, and comparisons were carried out using an independent t-test ( = 0.05). FFF-fabricated restorations showed the lowest fracture load values and CNC-fabricated the highest (p < 0.001). OV fabricated via DLP and CNC exhibited the highest fracture load (p < 0.001). For FFF, PC demonstrated the highest values (p < 0.028), whereas AC showed the lowest fracture load values (p < 0.001). VL showed higher initial SBS than MP (p < 0.001) and no impact on aging (p < 0.608). All MP samples showed debonding after thermocycling. Within PET and PMMA, no impact of luting/cement material on fracture load was observed (p = 0.116–0.282). The fracture load decreased after masticatory simulation (MP-PMMA: p < 0.001, VL-PMMA: p = 0.27). DLP-fabricated restorations showed the highest reproducibility and printing accuracy. CNC and FFF-PET showed comparable values. FFF-PMMA showed the greatest deviations. CNC-fabricated provisional restorations exhibited the highest fracture load. AC presented the lowest fracture load values. DLP provided the highest reproducibility and accuracy. VL achieved superior bonding to PMMA surfaces. Thermomechanical aging significantly reduced fracture load in both PET and PMMA restorations, regardless of luting material.