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Virtual reality technologies are important auxiliary tools in the process of learning and acquiring the manual skills necessary for clinical maneuvers in dental prosthodontics. This study shows the particularities in the use of the virtual simulation system designed for dental prosthodontics, compared to the classically preparations performed on resin models. The interactively simulation systems reproduce real clinical situations in which students practice specific dental prosthetics maneuvers. Resin models do not reproduce the accuracy of the dental structures at the time of the preparation. The advantages of using virtual technology are efficient clinical training, allowing for repeatability, self-assessment of procedures and the acquisition of manual skills. In this way, the advantages conferred by virtual simulators are superior to those resulting from the use of resin models in the acquirement of manual skills.

Among the properties of materials for direct coronal restorations, water absorption is particularly important, influencing the mechanical properties, color and adhesion of the restorations made.The aim of this study was to compare the water absorption of six dental restorative materials, two composite, two compomers and two glass ionomers. Water absorption was determined on disk samples. 30 discs were prepared, 5 of each studied material, with a diameter of 15 mm and a thickness of 1 mm. The water absorption test was carried out based on the ISO 4049 specification. The composites and compomers showed a water absorption within the standard limits (40 µg/mm3). Glass ionomers show high water absorption, therefore to be used as coronal restorative materials they need to be coated with a protective varnish.

Recent progress in Material Extrusion-based Additive Manufacturing (MEX) has introduced active foaming agents in filaments composition, thus allowing for the tuning, by various process parameters, the hardness and the mechanical behavior of 3D-printed parts. In case of thermoplastic polyurethane (TPU) filaments, these advances significantly broaden the range of applications, particularly in the domains of comfort and orthotics (wrist-hand orthoses, insoles), offering the dual benefits of design flexibility inherent in MEX and the comfort of lightweight and customizable structures. However, the field is still in its early stages, with only a limited number of research efforts dedicated to characterizing these novel materials. In this context, this study is focused on determining the influence of printing temperature (190°C, 220°C, 240°C), infill density (25%, 35%, 45%) and infill pattern (honeycomb, gyroid) over the hardness of cylindrical specimens made of Colorfabb varioShore TPU. A comprehensive methodology of calibration is also presented as mandatory for obtaining good quality and accurate products by establishing correlations between flow rate and printing temperatures. The findings showed that the printing temperature is the most relevant factor impacting the hardness of varioShore TPU prints. At a printing temperature of 190°C, which corresponds to less foamed prints, the honeycomb infill yielded higher hardness compared to the gyroid infill, but the difference was not significant. Also, at 220°C and 240°C, the mean values of hardness remain relatively consistent, regardless of infill density and pattern.

This article examines the impact of surface treatment of glass fibers on the strength of a composite material with an unsaturated polyester polymer matrix reinforced with glass fibers. The strength tests conducted include tensile, bending, and impact strength tests, as well as weight loss measurements. The research was conducted in two stages: in the first stage, the time was kept constant while the fibers were treated with varying concentrations of an alkaline NaOH solution; in the second stage, the concentration was fixed and the variable parameter was the treatment time. The results of the study indicate that surface treatment of glass fibers significantly improves their adhesion to the matrix materials, resulting in improved strength test results for the composite samples. The impact resistance, bending resistance, and tensile strength values all increased compared to the reference samples. However, certain changes in the individual parameters of fiber processing led to a slight decrease in tensile strength when it fell below the reference values. Additionally, it was observed that as the concentration of the solution and treatment time increased, the weight of the fibers decreased.

Last years research in polymers registered an increase of interest regarding polymer mixtures aiming to obtain materials with properties of the mixed polymers. In this respect many studies are pointing the mixtures between a thermoset polymer and a thermoplastic polymer. It is known the fact that thermoplastic polymers are much more malleable than the thermoset ones and the goal is to obtain a mixture with the general properties of the thermoset polymer and with a machining ability proper to the thermoset polymer. The vitrimers are this type of polymers and, some of them, can be obtained by mixing polymers form the two categories. This study is about using solutions of two thermoset polymers to modify the basic properties of three epoxy resins. The results show that the presence of PMMA, respectively, PLA inside the epoxy resin matrix determines changes of the mechanical properties of the formed materials. Without analysing the adhesive properties of new materials is hard to decide about their value from the composites applications point of view.

Since the invention of the first UAV’s, different industries realized it’s capabilities and potential uses. Drones and UAV’s are part of our everyday life and their development has seen an unprecedented speed due to their multiple applications, from scientific research to military applications. When we talk about UAV’s we also talk about composite materials. Today’s drones and UAV’s are using almost exclusively carbon fiber, glass fiber and 3D printed materials. This paper presents the development and testing of fiber carbon materials along with a future concept of an UAV. In the end of this paperthe results of testing the materials are presented.

The present work studies the positive or negative effect of zeolite mineral on the tensile and flexural mechanical behavior of a wood-plastic composite. Eight different blends were developed, the components used were wood flour (WF), polypropylene (PP), zeolite (Z) and maleic anhydride modified polypropylene (MAPP) as coupling agent. The eight blends were made using a counter-rotating twin-screw extruder, while the specimens were produced on a plastic injection molding machine with a 60ton clamping capacity. The standards used to determine the tensile and flexural mechanical properties were ASTM 638 and ASTM 790, respectively. Ten repetitions of each mixture were carried out. In addition, a reference (100% polypropylene) was used to compare the results obtained to determine whether the effect of using the zeolite mineral generated positive or negative results in the compounds obtained. Both studies showed that as the proportion of zeolite increases in the blend, the tensile and flexural properties are affected. However, the mixture (M7) with proportions in its components of, 34.375% WF, 55.875% PP, 6.75 % Z and 3% MAPP, showed an increase in the tensile and flexural mechanical properties, indicating a strong relationship between the components that integrate the wood-plastic composite (WPC), mainly between wood and mineral.

Personalizing prosthetic components based on individual anatomical landmarks can increase implant lifespan and it can reduce the postoperative complications due to prosthesis geometry that does not mold on the patient’s anatomy. This article aims to present a method of optimizing shoulder prostheses by conducting both medical and technological studies, based on which a personalized prototype was obtained, designed according to the patient`s landmarks. Thus, a computer-assisted methodology has been developed that targets the preoperative planning of shoulder arthroplasty starting from the traditional planning used by orthopedic surgeons, as well as the principles of determining the relevant humeral parameters. Initially, a set of DICOM CT (Digital Imaging and Communications in Medicine) patient scans with a presumed fracture at the glenohumeral joint requiring a shoulder arthroplasty was used. The acquired data were transferred to a medical image processing software, where was performed the bone segmentation, specifying the image processing algorithms used to reconstruct the geometry of the patient`s shoulder. The 3D model of the humerus obtained during this stage was imported into a CAD (Computer Aided Design) software application where the humeral anatomical landmarks were established and used to design a suitable prosthesis according to patient`s needs, which was manufactured through additive manufacturing using a biocompatible material.

Positive airway pressure (PAP) is the standard treatment for patients with moderate to severe obstructive sleep apnea, especially when a correctable anatomic obstacle is not identified. The PAP efficiency strongly depends on the appropriate use during sleep. Despite the recent advancements in PAP interface designs, overall adherence to therapy remains low. The main sources of discomfort consist of air leakage and mask overtightening leading to skin problems. However, these disadvantages have been partially reduced by new interfaces like nasal pillows that have the capacity to reduce the contact of the silicone cushion with the skin, reducing the chances of skin irritation. At the same time, assuring a better seal prevents air leakage and is particularly useful in patients with internal valve insufficiency. We present a case of a 57-year-old patient with severe sleep apnea syndrome whose efficient treatment was delayed by an inadequate PAP mask prescription at diagnosis. Due to low treatment compliance secondary to the perceived adverse effects of the oronasal mask, the patient decided to discontinue treatment for two years with subsequent aggravation of sleep apnea symptoms. The patient’s sensitivity to the silicone mask cushion and treatment ineffectiveness due to internal valve collapse were the main causes of treatment failure. After changing of PAP interface, the patient achieved long-term compliance. Our case report reflects the importance of choosing the most suitable PAP interface in accordance with the patient’s particularities. In the absence of this approach, appropriate treatment might be delayed with detrimental consequences, especially in severe cases. Considering PAP adherence following therapy initiation usually predicts long-term compliance, finding the best mask design from the beginning can predict therapeutic success.

The materials of the article are devoted to obtaining the material based on a mixture of natural rubber with the refractory cement filler in a certain proportion and the study of its physical and mechanical characteristics. The samples with different cement contents were formed to determine the optimal proportion of cement additives in the mixture. The resulting analysis showed that the material with a cement proportion of 15 (pphr) has the best characteristics, in which an increase in the values of the maximum tensile pressure (8.98 MPa) was achieved, a decrease in the values of elongation, while an increase in the value of hardness and wear resistance, and minimum level of absorption was observed when the samples were immersed in technical oil - by 1.29%.