Volume 63, Issue 2

Abstract: The consideration of additive manufacturing as a production method leads to a new approach with other elements of manufacturing technology systems. In this research article, a robot-assisted manufacturing method is considered in order to increase the efficiency and accuracy of the 3D printing process. There are two possibilities of 3D printing when a robot arm is used: a conventional one (plane-to-plane printing) and a non-planar/continuous one when a 3-dimensional trajectory is used. The aim of the research is to establish the differences between the mechanical properties and precision of 3D printed parts using these two methods of 3D printing. This paper presents a methodology used in control software for both the robotic arm and the extruder, converting 3D models into executable robotic instructions, and performing accurate hardware calibration. The material selected for the experiments was ONYX, which is a composite material that includes carbon fiber, which has better properties with respect to metal, namely, low weight, better mechanical strength, rigid parts under repeated loads, better adaptability for customization, and suitability for on-demand production. These properties are required in the automotive and aerospace industries. In the experiments carried out, several parameters were taken into account, such as UV radiation, humidity, nozzle diameter, and temperature (printing speed is constant). The samples were subjected to tensile tests, and the results obtained are discussed in the paper.

Abstract: This study aimed to comprehensively compare the flexural strength, degree of conversion (Dc), and repair flexural strength of three bulk-fill resin composites: SDR Plus, Beautifil Bulk Flow, and EverX Posterior under simulated clinical conditions. Specimens of each composite (n = 10) were fabricated and polymerized and their Dc was assessed using ATR-FTIR spectroscopy after 24 h. Bar-shaped specimens underwent thermocycling and were tested for flexural strength using a three-point bending test. Following the initial fracture, specimens were either repaired with the original composite or with Filtek™ Supreme Flowable Restorative and then retested. Failure modes were analyzed under stereomicroscopy. Data were statistically analyzed using one-way and two-way ANOVA with significance set at p < 0.05. EverX Posterior showed significantly higher flexural strength (153.48 MPa) but lower Dc (59.6%) compared to SDR Plus and Beautifil Bulk Flow, which presented higher Dc values (68.33% and 66.27%, respectively). Repair flexural strength varied depending on the composite and repair material, with fiber-reinforced EverX Posterior significantly benefiting from flowable composite repair. Adhesive failure was predominant except for some cohesive failures in EverX Posterior repaired with flowable resin. Fiber-reinforced composites demonstrated superior mechanical strength suitable for stress-bearing applications, while flowable bulk-fill composites achieved higher polymerization efficiency. Repair using flowable composites may enhance repair flexural strength, particularly for fiber-reinforced bulk-fill materials. However, as this was an in vitro study without long-term aging, fatigue, or bonding durability evaluation, the findings should be interpreted with caution and may not directly reflect long-term clinical performance.

Abstract: Background: Antiphospholipid syndrome (APS) is a major cause of pregnancy morbidity, characterized by antiphospholipid antibody–induced platelet activation and placental thrombosis. Integrin αIIbβ3 is a key mediator of platelet aggregation in this pathological process. Methods: We developed PEGDA-based hydrogels functionalized with acrylated RGD peptides to competitively bind αIIbβ3 and inhibit platelet aggregation. The effects of hydrogel and αIIbβ3 antibody treatments were evaluated in vitro using integrin-binding assays, turbidity-based platelet aggregation and clotting assays, ELISA for cytokine release, and transwell migration of trophoblasts. Results: RGD-modified hydrogels showed dose-dependent binding to αIIbβ3. Both hydrogel and antibody treatments significantly reduced antiphospholipid antibodies (aPL)-induced platelet aggregation, delayed fibrin clot formation, and suppressed IL-6 and TNF-α release from trophoblasts. Cell migration assays confirmed that these interventions preserved trophoblast motility impaired by aPL exposure. Conclusion: Targeting integrin αIIbβ3 with RGD-functionalized biomaterials or neutralizing antibodies effectively attenuated aPL-mediated thromboinflammation. This approach represents a promising localized intervention strategy to prevent APS-related pregnancy complications.

Abstract: Recycling polymeric waste is a key component of the circular economy, aiming to reduce environmental impact and resource consumption. However, polymeric blends obtained from mixed recycled plastics often exhibit variable mechanical properties due to differences in composition and compatibility among constituent polymers. This study investigates the flexural behavior of a recycled polymeric blend to assess its suitability for applications requiring moderate bending loads. Samples consisting of approximately 70% polyethylene (LDPE and HDPE), 20% polypropylene, and minor fractions of ABS, PET, and PA6/6 were fabricated by a two-stage extrusion–molding process without washing or compatibilization. Three-point bending tests were conducted in accordance with SR ISO 178:2019 using an Instron 5982 universal testing machine at five crosshead speeds (10–1000 mm/min). Mechanical parameters—including maximum force, flexural stress, Young’s modulus, strain, and absorbed energy—were determined. Differential scanning calorimetry (DSC) was employed to confirm blend composition and homogeneity. The recycled blend exhibited flexural stress values between 14 and 19 MPa and a flexural modulus ranging from 0.61 to 0.83 GPa, with minimal dependence on test rate. The absorbed energy at 50 mm displacement varied between 14 J and 18.5 J, and no cracking or brittle fracture occurred at any test rate. The material displayed good elastic recovery after the test and a narrow standard deviation across all mechanical parameters, indicating reproducibility and homogeneity. The results demonstrate that the recycled polymeric blend possesses stable and repeatable mechanical performance under bending, comparable to conventional HDPE/LDPE or PP-based materials. Its low rate sensitivity and energy absorption capacity support its potential use in non-structural or moderately loaded components (up to ~12 MPa), providing a viable, eco-friendly alternative to virgin polymers or wood-based materials in various applications.

Abstract: This study investigates the accuracy of stereolithography (SLA)-printed occlusal devices fabricated at orientations of 0° and 45°, addressing a gap in the literature regarding printing orientation, technology and clinical performance. Despite their nascent application, the clinical performance of these materials remains largely unexplored. The primary objective was to evaluate the clinical efficacy of 3D-printed occlusal devices (OC) in a prospective, double-blind study involving 40 participants divided into four groups: conventionally fabricated polymethyl methacrylate (PMMA) occlusal devices (CPMMA), CAD/CAM milled PMMA (MPMMA), and 3D-printed OCs at 0 degrees (3D 0°) and 45 degrees (3D 45°). Conventional impressions and gypsum casts were digitized and designed for milling from PMMA blocks, while the 3D-printed groups used Dental LT resin (Formlabs, Sommerville, MA, USA) in a Form 2 printer (Formlabs, MA, USA). Clinical assessments were conducted at baseline and six months post-treatment, focusing on OC surface roughness, OC surface wear, antagonist tooth wear, occlusal device fit, and therapeutic efficacy. One-way ANOVA and post hoc tests were applied for statistical analysis. Results showed no significant therapeutic differences among groups, although all participants exhibited improvements in palpation and mandibular movement scores (p > 0.001). No significant difference was observed in surface wear between the MPMMA and 3D 0° groups, while the difference between the other groups was significant (p < 0.001). Significant antagonist tooth wear variations (p < 0.001) were noted, with the MPMMA and 3D 0° groups showing less wear compared to the control group. The findings indicate that 3D-printed occlusal devices yield clinically acceptable outcomes, demonstrating performance comparable to traditional materials, with printing orientation potentially influencing antagonist tooth wear. The 3D-printed OC demonstrates adequate surface roughness, wear resistance, device fit, and therapeutic efficacy.

Abstract: The effective treatment of skin wounds remains a challenge, largely due to complications from bacterial infections. In this study, polyvinylidene fluoride (PVDF)/polyethylene oxide (PEO) nanofibrous membranes incorporated with azithromycin (AZ) were fabricated via electrospinning as a novel antibacterial wound dressing. The morphology, chemical composition, and wettability of the nanofibers were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and contact angle analysis, respectively. Antibacterial evaluations demonstrated that increasing AZ concentration significantly enhanced the inhibition zones, confirming strong antibacterial performance. Furthermore, in vivo experiments on Staphylococcus aureus–infected rat wounds revealed that the PVDF/PEO/AZ membranes effectively suppressed suppuration and maintained a cleaner wound surface. These results highlight the potential of AZ-loaded PVDF/PEO nanofiber dressings as promising candidates for advanced wound care, combining biocompatibility, structural integrity, and sustained antibacterial activity.

Abstract: Background: Sepsis-induced inflammation and oxidative stress lead to multi-organ dysfunction with limited treatment options. Biomaterials with intrinsic immunomodulatory properties may offer a novel therapeutic strategy. Materials and Methods: A physically crosslinked hydrogel composed of polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), and tannic acid (TA) was developed. Its physicochemical properties and cytocompatibility were evaluated. In vitro models using Human Umbilical Vein Endothelial Cell (HUVEC), Human Kidney-2 Cell (HK-2), and Human Hepatocellular Carcinoma G2 Cell (HepG2) cells were used to simulate LPS-induced inflammatory injury. A triple-cell co-culture system was established to assess cytokine crosstalk and hydrogel intervention. Results: The hydrogel exhibited favorable swelling, degradation, and cytocompatibility. LPS stimulation induced significant cell injury, ROS elevation, mitochondrial disruption, and increased pro-inflammatory cytokine levels. Hydrogel treatment restored cell viability, reduced ROS, preserved mitochondrial morphology, and suppressed TNF-β, IL-6, and IL-1β while upregulating IL-10. These effects persisted in the co-culture model. Conclusion: The PVA/CMC/TA hydrogel effectively attenuates LPS-induced cellular and immunological injury through antioxidant and anti-inflammatory mechanisms. This drug-free biomaterial shows promise as a supportive therapeutic platform for sepsis-related inflammatory disorders.

Abstract: Traditional synthetic polymers pose significant risks to the environment, and native starch-based films usually have impaired mechanical strength and lack physical functionality. This paper explores the physical, mechanical, and morphological characteristics of the first biocomposite films made of arrowroot thermoplastic starch (AS) reinforced with different concentrations (1, 3, 5, and 10 wt%) of graphene nanoplatelets (GNP). The films were made by a more traditional solution-casting technique in a combination of glycerol and sorbitol as a plasticizer. The findings showed that there was a positive relationship between GNP loading and film thickness, with density reaching a maximum loading of 1% and then levelling off because of the agglomeration effect of fillers. Mechanical testing results showed that the addition of 5% GNP maximized the strength of the material, where the tensile strength was a maximum of 2.83 MPa, and the Young’s modulus was 128.25 MPa, which was a great improvement over that of the neat starch control. Interestingly, the elongation at break was highest with 3% GNP loading (14.37%), and this indicated an optimum ductile balance. Field Emission Scanning Electron Microscopy (FESEM) verified that low-to-moderate loadings resulted in dense and integrated microstructure, whereas higher concentrations (10%) resulted in high agglomeration of GNP and micro-voiding. Further tests showed that GNP reinforcement enhances thermal stability and resistive response by means of Differential Scanning Calorimetry (DSC) and electrical characterisation, respectively. These results are indicative of the fact that optimised AS/GNP biocomposites are a potential, environmentally appropriate, and inexpensive substitute for the next generation of flexible electronic sensors and devices.

Abstract: Background: Thyroid cancer remains the most common endocrine malignancy, and a subset of patients exhibit aggressive invasion and recurrence. Conventional two-dimensional culture models fail to replicate the three-dimensional (3D) tumor microenvironment, underscoring the need for biomimetic scaffolds to study invasion and therapy response. Methods: GelMA/SA double-network hydrogels with different ratios (3:1, 1:1, 1:3) were fabricated by sequential photocrosslinking and ionic crosslinking. Their swelling, degradation, and mechanical properties were characterized, and microstructures were examined by scanning electron microscopy. Human papillary thyroid carcinoma cell lines (TPC-1 and BCPAP) were encapsulated to evaluate viability, morphology, and invasive behavior. Results: The hydrogel composition strongly influenced structural and biological performance. SA-rich gels showed excessive swelling, rapid degradation, and poor pore formation, while GelMA-rich gels were stable but less porous. The intermediate 1:1 formulation exhibited balanced swelling and degradation, uniform pores, and enhanced tensile and compressive strength. Encapsulated cells in the 1:1 gels displayed robust viability, extended pseudopodia, and maintained expression of invasion-related markers(N-cadherin, MMP-9). Conclusion: The GelMA: SA = 1:1 double-network hydrogel provides the most favorable microenvironment for thyroid cancer cell invasion modeling, combining porosity, stability, and bioactivity. This 3D platform offers a reliable tool for mechanistic studies and therapeutic evaluation in thyroid cancer.

Abstract: This study aimed to evaluate whether the combination of Vitapex paste and minocycline hydrochloride ointment offers superior therapeutic benefits for combined periodontal–endodontic lesions. A total of 109 patients with combined periodontal-endodontic lesions treated in our hospital were prospectively selected and divided into a control group (n = 54, treated with minocycline hydrochloride ointment + iodoform-zinc oxide eugenol paste) and a study group (n = 55, treated with minocycline hydrochloride ointment + Vitapex paste) using a random number table. The treatment lasted for eight weeks in both groups. The periodontal status [gingival index (GI), plaque index (PLI), clinical attachment level (CAL), and probing depth (PD)], levels of inflammatory cytokines in gingival crevicular fluid (GCF) [interleukin-1β (IL-1β), IL-17, and tumor necrosis factor-α (TNF-α)], pain degree and tooth function were also compared. The study group achieved a higher total effective rate compared with the control group (96.36% vs. 83.33%). After treatment, both groups showed significant reductions in GI, PLI, CAL, PD, and GCF levels of IL-1β, IL-17, and TNF-α, with greater improvements observed in the study group. Pain scores (VAS, PPI, PRI) also decreased more markedly in the study group. Furthermore, occlusal force and masticatory efficiency improved significantly in both groups, with superior enhancement in the study group. Root canal injection of Vitapex paste combined with minocycline hydrochloride ointment demonstrates superior clinical efficacy in treating combined periodontal-endodontic lesions, effectively reducing inflammation, improving periodontal parameters, relieving pain, and enhancing tooth function.