In this study, 3D printing of poly-l-lactic acid (PLLA) scaffolds reinforced with graphene oxide (GO) nanoparticles via Digital Light Processing (DLP) was investigated to mimic bone tissue. Stereolithography is one of the most accurate additive manufacturing method, but the dominant available materials used in this method are toxic. In this research, a biocompatible resin (PLLA) was synthetized and functionalized to serve the purpose. Due to the low mechanical properties of the printed product with the neat resin, graphene oxide nanoparticles in three levels (0.5, 1, and 1.5 Wt.%) were added with the aim of enhancing the mechanical properties. At first, the optimum post cure time of the neat resin was investigated. Consequently, all the parts were post-cured for three hours after printing. Due to the temperature-dependent structure of GO, all samples were placed in an oven at 85 ° C for different time periods of 0, 6, 12, and 18 hours to increase mechanical properties. The compression test of heat treated samples reveals that the compressive strength of the printed parts containing 0.5,1, and 1.5 % of GO increased by 151,162 ad 235%, respectively. Scaffolds with the designed pore sizes of 750 microns and a porosity of 40% were printed. Surface hydrophilicity test was performed for all samples showing that the hydrophilicity of the samples increased with increasing GO percentage. The degradation behavior of the samples was evaluated in a PBS environment, and it revealed that by increasing GO, the rate of component degradation increased, but the heat treatment had the opposite effect and decreased the degradation rate. Finally, besides improving biological properties, a significant increase in mechanical properties under compression can introduce the printed scaffolds as a suitable option for bone implants.

Printed oral splints are a therapeutic alternative in the treatment of functional disorders. Their mechanical properties are crucial to their clinical success and their performance can vary depending on cleaning, post-polymerization, or build orientation. This in vitro study aimed to compare the biaxial flexural strength of the chosen materials depending on the aforementioned parameters. 720 discs (n = 15 per group, 16 mm x 2 mm) were printed from splint materials. Printing was performed under 90°, 45°, or 0° orientation to the building platform with supporting structures. Specimens were either automatically or manually cleaned with isopropanol. Post-polymerization was performed with LED- or Xenon-light. Biaxial flexural strength (BFS) was determined with a piston-on-3-ball test after 24 hours or 60 days water storage (37°C). Test specimens were preloaded with 0.5 N and the load was applied by a piston of 1.6 mm in diameter at 1 mm/min crosshead speed. Statistics were performed by using descriptive statistics, ANOVA, and Levene-tests. Mean BFS after 24 hours of storage varied between 79 MPa and 157 MPa. After 60 hours the BFS significantly decreased and revealed values ranging from 72-127 MPa (mean24 113 MPa, mean60 97 MPa; p<0.001). No significant differences could be determined between the materials (p=0.103) or between the different cleaning procedures (p=0.321). Post-polymerization yielded higher means with LED- (P1: 115 MPa) than with Xenon-light (P2: 95 MPa; p<0.001). Regarding position, the mean values ranged from 101 MPa for 0°, 102 MPa for 45°, and 115 MPa for 90°, which was significantly different (p<0.001). Build orientation of 90° and post-polymerization with LED-light provided significantly higher biaxial flexural strength and should be used to guarantee optimal strength of splint materials. Aging decreased the biaxial flexural strength of the tested specimens.

Objective: The aim of this in vitro study was to evaluate the accuracy of resin-based fixed dental restorations, namely veneers, single crowns, and four-unit fixed partial dental prosthesis (FPDs) using two different 3D printers and polymer-based materials. Materials and Methods: A standard maxillary polyurethane jaw model containing prepared teeth was scanned using an intraoral scanner. The generated STL data were used to design the restorations virtually using CAD software. Two 3D printers were utilized for the provisional digital light processing and stereolithography for the castable resin patterns. Each printer produced 10 specimens of each type of restoration, for a total of 80 restorations. The 3d-printed restorations were then 3D scanned using the same intraoral scanner and evaluated for external and internal dimensional accuracy in terms of trueness and precision. A one-way ANOVA and Two-sample T-Test were implemented to compute the precision (variability between groups) and trueness (with the designed CAD model). A level of statistical significance of p-Value

The widespread use of epoxy resin (ER) in industry, owing to its excellent properties, aligns with the global shift toward greener resources and energy-efficient solutions, where utilizing metal oxides in 3D printed polymer parts can offer extended functionalities across various industries. ZnO concentrations in polyurethane acrylate composites impacted adhesion and thickness of DLP samples, with 1 wt.% achieving a thickness of 3.99±0.16 mm, closest to the target thickness of 4 mm, while 0.5 wt.% ZnO samples exhibited the lowest deviation in average thickness (±0.03 mm). Tensile strength in digital light processed (DLP) composites with ZnO remained consistent, ranging from 23.29 MPa (1 wt.%) to 25.93 MPa (0.5 wt.%), with an increase in ZnO concentration causing a reduction in tensile strength to 24.04 MPa and a decrease in the elastic modulus to 2001 MPa at 2 wt.% ZnO. The produced DLP samples, with their good corrosion resistance in alkaline environments, are well-suited for applications as protective coatings on tank walls. Customized DLP techniques can enable their effective use as structural or functional elements, such as in Portland cement concrete walls, floors and ceilings for enhanced durability and performance.

The results of studying the effect of particles of few-layer graphene (FLG) synthesized by self-propagating high-temperature synthesis (SHS) on the complex of strength and thermo physical properties of polymer composite products obtained by DLP 3D printing are presented. It has been discovered to achieve an increase in thermo physical and strength parameters of polymers modified by FLG compared with samples made on the unmodified base resin. This result was achieved due to low defectiveness, namely the absence of Stone-Wales defects in the structure of FLG due to the homogeneous distribution of FLG over the volume of the polymer in the form of highly dispersed aggregates. It was possible to increase hardness by 120 %, bending strength by 102 %, Charpy impact strength by 205 %, and thermal conductivity at 25 °C by 572 % at concentrations of few-layer graphene of no more than 2 wt. %.

Different approaches for digital workflows have already been presented for their use in palatal plates for newborns and infants. However, there is no evidence on the accuracy of CAD/CAM manufactured orthodontic appliances for this kind of application. This study evaluates trueness and precision provided by different CAM technologies and materials for these appliances. Samples of a standard palatal stimulation plate were manufactured using stereolithography (SLA), direct light processing (DLP) and subtractive manufacturing (SM). The effect of material (for SM) and layer thickness (for DLP) were also investigated. Specimens were digitized with a laboratory scanner (D2000, 3Shape) and analyzed with a 3D inspection software (Geomagic Control X, 3D systems). For quantitative analysis, differences between 3D datasets were measured using root mean square (RMS) error values for trueness and precision. For qualitative analysis, color maps were generated to detect locations of deviations within each sample. SM showed higher trueness and precision than AM technologies. Reducing layer thickness in DLP did not significantly increase accuracy, but prolonged manufacturing time. All materials and technologies met the clinically acceptable range and are appropriate for their use. DLP with 100µm layer thickness showed the highest efficiency, obtaining high trueness and precision within the lowest manufacturing time.

Advanced ceramics are recognized as key enabling materials possessing combinations of properties not achievable in other material classes. They are characterized by very high thermal, chemical and mechanical resistance and also usually have a lower density than metals. These properties predestine ceramics for many different applications, especially space applications.In the aerospace sector aerospike nozzles promise performance and application advantages compared to classic bell nozzles but are also inherently more complex to manufacture due to their shape. AM methods drastically simplify or even enable the fabrication of those complex structures while minimising the number of individual parts. The applicability of ceramic AM (“CerAMfacturing”) on rocket engines and especially nozzles is consequently investigated in the frame of the “MACARONIS” project, a cooperation of the Institute of Aerospace Engineering at Technische Universität Dresden and the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) in Dresden. The goal is to develop novel large size aerospike thrust nozzles including areas of highest resolution and fineness. Finding a suitable AM process that enables the realisation of both aspects is extremely challenging. One possibility could be the hybridization of shaping methods, in that case CerAM VPP (ceramic additive manufacturing via vat photopolymerization) and CerAM FFF (ceramic additive manufacturing via fused filament fabrication) in combination with sinter joining. This contribution focuses on the high resolution CerAM VPP process, in particular the development, characterization and testing of a new photoreactive Al₂O₃ suspension validated by AM of novel aerospike nozzles.