Contemporary thermoplastic monomer-free prosthetic materials are widely used nowadays, and there are a great variety available on the market. These materials are of interest in terms of the improvement of the quality features of the removable dentures. The aim of this study is to establish how minimal changes in the laboratory protocol of polyamide prosthetic base materials influence the surface texture. Two polyamide materials intended for the fabrication of removable dentures bases were used—Perflex Biosens (BS) and VertexTM ThermoSens (TS). A total number of 20 coin-shaped samples were prepared. They were injected under two different modes—regular, as provided by the manufacturer, and modified, proposed by the authors of this study. Scanning electronic microscopy (SEM) under four magnifications—×1000, ×3000, ×5000, and ×10,000—was conducted. With minimal alterations to the melting temperature (5 °C) and the pressure (0.5 Bar), in Biosens, no changes in terms of surface improvement were found, whereas in ThermoSens, the surface roughness of the material significantly changed in terms of roughness reduction. By modifying the technological mode during injection molding, a smoother surface was achieved in one of the studied materials.

The current study sought to investigate the changes in surface hardness, roughness, and moisture absorption of the Vertex ThermoSens polymer (Vertex Dental, 3D Systems, The Netherlands) following immersion in artificial saliva for various periods (7, 14, and 28 days). A total of 60 rectangular specimens with dimensions of 20 mm in length, 20 mm in width, and 3 mm in thickness were made. Due to insufficient mold solidification, these specimens were made utilizing the injection molding process. A Mitutoyo Surftest 4 roughness meter (Mitutoyo, Aurora, IL, USA) was used to measure the surface roughness of the test materials. The ThermoSens polymer hardness was assessed using the Shor method and D—HSD scale, while absorption was measured with a Sartorius analytical balance. Results indicated the highest mean hardness after 28 days (M = 77.6) (Surface 1) and the lowest for the control group (M = 59) (Surface 2). The maximum surface roughness occurred in direction 2.2 pre-immersion (Ra = 2.88 μm) and 7 days post-removal (Ra = 2.95 μm). The control group exhibited the lowest absorption (Wsp = 1.524 mg/mm³), with the highest mean values over 28 days (Wsp = 1.541 mg/mm³). The elevated flask and plaster temperature slowed polymer solidification, resulting in longer macromolecules and improved mechanical properties and surface features.

This work presents the results of deposition by magnetron sputtering nanostructured multilayer Cr/(Cr/a-C)ml coatings on AISI 316L and AISI 321 steel substrates. Chemical compositions were confirmed through EDX analysis with scanning electron microscopy. The coating thickness was measured with Calotester (KaloMAX II) and the total thickness of the coatings obtained ranged from 1.684 ± 0.193 μm for AISI 316L to 1.749 ± 0.123 μm for AISI 321. A Daimler-Benz Rockwell indentation test for adhesion quality and a nanoindentation test with a Berkovich indenter were carried out. According to the Raman spectroscopy analysis and in agreement with mechanical tests, it is supposed that it is the formation of a diamond-like carbon phase which enhances the mechanical properties. The hardness values obtained for the nanostructured multilayer Cr/(Cr/a-C)ml coatings were improved compared to those of the base stainless steels.

The process of hardening a hypereutectic aluminium-silicon alloy AlSi18 in unmodified, modified and nano-modified state has been studied. Two types of modifiers have been used - a standard modifier P, introduced into the melt by means of the ligature CuP 0,4wt.%, and a nanomodifier (nanodiamonds - ND) 0,1wt.%. The influence of the various types of modifiers on the process of crystallization, as well as on the size of the primary Si crystals in the structure of the alloy and their distribution in it has also been discussed.

Introduction. Studies have been carried out with the following types of an aluminum-silicon AlSi18 alloy: unmodified, modified by a standard P modifier, modified by a SiC nanomodifier, and modified by a combination of both types if modifiers. The paper discusses the influence of the different types of modifiers and the combination of them on the shape and size of the primary Si crystals and their distribution in the structure of the alloy, as well as on the shape and size of the Si crystals in the eutectic composition.