The aim of this study was to develop a polyethylene/polyamide (R-PE/R-PA) regranulated product made from post-consumer wastes grafted with polyethylene-graft-maleic anhydride (PE-g-MAH) by reactive extrusion in a twin-screw extruder equipped with an external mixing zone. The compatibility effect of PE-g-MAH used as a modifier in R-PE/R-PA blends was evaluated by means of differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA), while the analysis of the chemical structure of this blend was carried out by Fourier transform infrared spectroscopy (FT-IR). The thermal properties, complex viscosity, and selected usage properties of R-PE/R-PA blends compatibilized with PE-g-MAH, i.e., density and water absorption, were evaluated. The morphology of the blends with and without the compatibilizer was observed by scanning electron microscopy. The R-PE/R-PA/MAH blend shows heterogenic structure, which is a result of the chemical reaction in reactive extrusion between functional groups of PE-g-MAH used as modifier and the end groups of R-PA6. The results show that the R-PE/R-PA blend with increased PE-g-MAH content showed increased hardness, stiffness, and ultimate tensile strength due to the increased degree of crystallinity. The increase in crystallinity is proportional to the improvement of the mechanical properties. Moreover, it is shown that 1 wt.% PE-g-MAH added to the R-PE/R-PA waste blend increases the interfacial interactions and compatibility between R-PE and R-PA, resulting in decreased polyamide particle size. Finally, the results show that it is possible to produce good quality regranulated products with advantageous properties and structure from immiscible polymer waste for industrial applications.

Fast-setting bioactive cements were developed for the convenience of retrograde fillings during endodontic microsurgery. This in vitro study aimed to investigate the effect of irrigation on the washout of relatively fast-setting materials (Biodentine, EndoCem Zr, and MTA HP) in comparison with MTA Angelus White and IRM in an apicectomy model. Washout resistance was assessed using artificial root ends. A total of 150 samples (30 for each material) were tested. All samples were photographed using a microscope, and half of them were also scanned. The samples were irrigated and immersed in saline for 15 min. Then the models were evaluated. Rinsing and immersing the samples immediately after root-end filling and after 3 min did not disintegrate the fillings made of all tested materials except Biodentine. Root-end fillings made of Biodentine suffered significant damage both when rinsing was performed immediately and 3 min after the filling. Quantitative assessment of washed material resulted in a slight loss of IRM, EndoCem MTA Zr, and MTA HP. MTA Angelus White showed a slightly greater washout. Rinsing and immersion of Biodentine restorations resulted in their significant destruction. Under the conditions of the current study, the evaluated materials, excluding Biodentine, showed good or relatively good washout resistance.

Background: The aim of this in vitro study was to determine the mechanical and functional properties of zirconium oxide ceramics made using 3D printing technology and ceramics produced using conventional dental milling machines. Methods: Forty zirconia samples were prepared for this study: the control group consisted of 20 samples made using milling technology, and the test group consisted of 20 samples made using 3D printing technology. Their surface parameters were measured, and then their mechanical parameters were checked and compared. Density, hardness, flexural strength and compressive strength were tested by performing appropriate in vitro tests. After the strength tests, a comparative analysis of the geometric structure of the surfaces of both materials was performed again. Student’s t-test was used to evaluate the results (p < 0.01). Results: Both ceramics show comparable values of mechanical parameters, and the differences are not statistically significant. The geometric structure of the sample surfaces looks very similar. Only minor changes in the structure near the crack were observed in the AM group. Conclusion: Ceramics made using additive technology have similar mechanical and surface parameters to milled zirconium oxide, which is one of the arguments for the introduction of this material into clinical practice. This in vitro study has shown that this ceramic can compete with zirconium made using CAD/CAM (Computer-Aided Design and Computer-Aided Manufacturing) methods.

The article presents the results of the research related to the decomposition of polylactic acid (PLA)/halloysite nanotube (HNTs) biocomposites into a simple organic form. After manufacturing the nanocomposites, the evaluation of the composting process simulation was conducted using the biodegradation method. First, the selected properties of PLA/HNTs biocomposites, such as density, water absorption, and impact strength were tested. Next, the impact of the composting process on the behavior of PLA/HNTs composites was investigated from 30 to 90 days. Finally, the loss of mass of the composites, hardness, and the structural changes of biocomposites under the composting conditions before and after the composting were evaluated using SEM microscopy. The results showed that the PLA modified by HNT particles has biodegradation-friendly properties and therein is fully suitable for organic recycling. Due to this, in the coming years, it may contribute to the replacement of non-biodegradability polymers, i.e. polyolefins and polyesters, and reduction of plastic packaging wastes.

Background: Pregnancy is a physiological state during which inflammation occurs. This complex biological response is necessary for the implantation process as well as delivery. In turn, its suppression during gestation favors the normal course of the pregnancy. Therefore, the presence of pro-resolving mediators, EPA and DHA derivatives, The aim of this study was to investigate the changes in the levels of anti-inflammatory resolvins and their precursors in different trimesters of pregnancy with consideration of the women’s weight, including overweight and obese women before pregnancy. Methods: A total of 78 women participated in this study; the mean age and BMI before pregnancy were 32.3 ± 5.52 and 27.73 ± 6.13, respectively. The patients were divided into two groups, considering their BMI before pregnancy. The extraction of eicosanoids was performed by high-performance liquid chromatography. The results obtained were subjected to statistical analysis. The levels of all studied parameters showed statistically significant differences between the study group (SG) and the control group (CG) in the different trimesters of pregnancy. Over the course of pregnancy, the levels of protection (PDX), maresin, resolvins (RvD1, RvE1), and their precursors differed in relation to the trimester of pregnancy and the division into groups considering the correct body weight before pregnancy. Results: Overweight or obese women had significantly lower levels of RvE1 in the third trimester and their precursors compared to normal-weight women. While the levels of PDX and RvD1 were significantly higher, this may be due to both a lower intake of products rich in omega-3 fatty acids by obese women and an increased need of obese women’s bodies to quench chronic inflammatory processes associated with obesity. Conclusions: Both EPA and DHA derivatives are involved in calming down inflammation during pregnancy, which was observed.

Introduction: The aim of this study was to investigate the effect of thermal cycling on the surface geometry of high-viscosity bulk-fill resin-based composites (RBCs) compared to conventional nanohybrid composites.Materials and methods: Four conventional nanohybrid composites (Tetric EvoCeram – TEC, GrandioSO – GD, Filtek Z550 – FZ, and Ceram·X Mono – CX) and 4 high-viscosity bulk-fill composites (Tetric EvoCeram Bulk Fill – TBF, X-tra fil – XF, Filtek Bulk Fill Posterior – FBF, and QuixFil – QF) were tested. After the 2-step polishing procedure, the samples were divided into 2 groups: control group (K) and thermal cycling group (TC). Samples from the TC were subjected to thermal cycling according to ISO 11405 (THE-1100, SD Mechatronik GmbH). Surface geometry was evaluated by profilometry (Turbowave v. 7.36, Hommel-Etamic) and scanning electron microscope – SEM (VEGA 3, Tescan Analytics).Results: The applied thermal cycles increased the surface roughness of conventional RBCs: TEC (p = 0.000007), GD (p = 0.04), and CX (p = 0.0005). A reduction in the surface roughness of bulk-fill composites was observed in the case of materials: XF (p = 0.000003) and QF (p = 0.0002). Thermal cycling was shown to alter the surface roughness of the TEC, CX, XF, and QF materials. Conclusion: The application of thermal cycling in a water environment in accordance with the ISO 11405 standard causes the degradation of the organic matrix and the exposure of filler molecules on the surface of both conventional and high-viscosity bulk-fill composites. Some of the tested RBCs, especially those containing modern hydrophobic monomers, are less susceptible to these processes.