Vat photopolymerization 3D printing, including stereolithography (SLA), digital light processing (DLP), and masked SLA (mSLA), has transformed dental device fabrication by enabling precise and customizable components. However, the rheological behavior of photopolymer resins is a critical factor that governs the printability, accuracy, and performance of printed parts. This review surveys the role of viscosity, shear-thinning, and thixotropy in defining the “printability window” of dental resins and explores the relationship between these properties and the formulation and final material performance. Rheological characterization using rotational rheometry provides key insights, with shear rate sweeps and thixotropy tests quantifying whether a resin behaves as Newtonian or pseudoplastic. The literature shows that optimal printability typically requires resins with low to moderate viscosity at shear, moderate thixotropy for stability, and formulations balanced between high-strength oligomers and low-viscosity diluents. The addition of fillers modifies the viscosity and dispersion, which can improve reinforcement but may reduce print resolution if not optimized. Thermal and optical considerations are also coupled with rheology, affecting the curing depth and accuracy. In conclusion, controlling resin rheology is essential for bridging material formulation with reliable clinical outcomes, guiding both resin design and printer process optimization in modern dental applications.

Additive manufacturing of continuous fibre-reinforced composites enables lightweight and structurally efficient solutions for aerospace applications. In this work, specimens were fabricated with an Anisoprint Composer A3^® printer using carbon fibres and a polyamide (PA) matrix. Unidirectional samples were mechanically tested to determine the Young’s modulus and establish the baseline stiffness of the printed system. Tensile test revealed a Young’s modulus of 37.84 GPa, and three-point bending testing indicated a bending modulus of 26.4 GPa. To improve quality, printing parameters were varied to reduce void formation, and computed tomography (CT) scans were used to quantify porosity. Lowest obtained specimen porosity volume content was 10.06%. To extend the experimental investigation, a numerical representative volume element (RVE) model with three constituents, matrix, fibres, and voids, was developed based on the CT images. This approach provides realistic microstructural representation and offers predictive capability for effective material properties, particularly in assessing the role of voids on stiffness. At the structural level, several wing rib geometries representative of small fixed-wing UAVs were printed and tested. Crushing forces were normalized by weight to evaluate load-bearing efficiency. Results indicate that analysed rib designs combined with reduced porosity improve strength-to-weight performance. The integration of mechanical testing, CT-based analysis, and RVE modelling demonstrates a comprehensive pathway to optimize fibre-reinforced composites in UAV design.

Clear aligners can be carriers of bleaching agents as pretreatment before orthodontic and prosthodontic treatment and therefore are exposed to the influence of the oral cavity and oxidizing agent. In this research, the effects of 14 days’ intra-aligner bleaching with 10% carbamide peroxide during clinical treatment on the thermomechanical behavior and infrared fingerprint of Nuvola^® aligners were assessed. Five experimental groups were tested (six DMA specimens in each group): control (not used), 14 days wear without bleaching, and 14 days wear with bleaching for 3, 7, and 14 days. The onset glass transition temperature (Tg) was determined by dynamic mechanical analysis, and Fourier-transform infrared spectroscopy (FTIR) was applied for qualitative evaluation of the chemical fingerprint of PETG. Statistically higher Tg was found in bleached groups than in the control and wear-only groups, although the values differed only between 78.35 and 79.23 °C. No trend of changes depending on exposure duration was found. There were no shifts in FTIR peaks, no additional bands appeared, and no characteristic bands disappeared. Thus, bleaching caused a statistically significant but small Tg increase and did not alter the infrared fingerprint of PETG. Low-level chemical modification below the sensitivity of qualitative FTIR cannot be excluded.

The clinical effectiveness of clear orthodontic aligners mainly depends on the thermomechanical stability of the polymers in this challenging hydrothermal environment. In this study, we compare the water-induced viscoelastic changes and glass transition temperature (Tg) stability of four polymers with different microarchitectures. Specifically, we examined directly printed photopolymer networks (Tera Harz TC-85 and LuxCreo 4D Aligner), a monolithic thermoplastic (Duran+), and a multilayer thermoplastic (ClearCorrect). Samples were immersed in physiological saline (0.9 wt.% NaCl) at 37 °C for 7 days, and Dynamic Mechanical Analysis (DMA) was performed in three conditions: dry, after immersion, and after a 2 h desorption step, mimicking a typical clinical 22:2 wear cycle. All polymers showed a decrease in Tg after immersion, with TC-85 exhibiting the greatest reduction relative to the dry baseline. Tg recovery after a 2 h ambient desorption step was incomplete and was significantly associated with the amount of water retained after 2 h drying (expressed as % of initial uptake; R² = 0.419), whereas total water absorption after 7 days was not associated with short-term thermal recovery.