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Background: While polyethylene terephthalate glycol (PETG) is widely used in orthodontic appliances such as clear aligners and retainers, there is limited experimental data assessing its performance under functional stresses, such as those encountered during dental movements and palatal expansion. Objective: This study aims to evaluate the ability of PETG thermoplastic material to withstand deformation under functional and expansion forces, specifically within the context of orthodontic applications. Subjects and Methods: To estimate the firmness of the screw within the appliance, a universal Instron testing machine was used to record the forces released by each activation of the expander within the upper part of 10 clear modified twin blocks (MTBs) made from PETG and compare it with that released by 10 conventional twin blocks (CTBs). On the other hand, to determine the ability of the thermoplastic appliance to withstand the deformation during functional forces, a three‐point bending test was used to investigate the response of both appliances under static loading. Independent samples t ‐test was used to compare the differences between groups. Results: Both CTB and MTB groups follow the same pattern of increase and decrease in the amount of mean load with the CTB group line showing a considerably higher amount of mean load reaching the peak (334.5 N) at turn 25 of screw activation while the peak of mean load for MTB group was equal to 252.6 N at turn 23. There was a statistically significant difference between the CTB and MTB groups in the three‐point bending test ( p = 0.001). However, both appliances did not deform at the required force. Conclusions: The MTB can withstand both required expansion and functional load without deformation. Trial Registration: ClinicalTrials.gov identifier: NCT06116500 .

Incorporation of nanocellulose could improve wear resistance of ultra-high molecular weight polyethylene (UHMWPE) for an artificial joint application. Yet, the extremely high melt viscosity of the polymer may constrict the mixing, leading to fillers agglomeration and poor mechanical properties. This study optimized the processing condition of UHMWPE/cellulose nanofiber (CNF) bionanocomposite fabrication in triple screw kneading extruder by using response surface methodology (RSM). The effect of the process parameters—temperature (150–190 °C), rotational speed (30–60 rpm), and mixing time (30–45 min)—on mechanical properties of the bionanocomposites was investigated. Homogenous filler distribution, as confirmed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, was obtained through the optimal processing condition of 150 °C, 60 rpm, and 45 min. The UHMWPE/CNF bionanocomposites exhibited improved mechanical properties in terms of Young’s and flexural modulus by 11% and 19%, respectively, as compared to neat UHMWPE. An insignificant effect was observed when maleic anhydride-grafted-polyethylene (MAPE) was added as compatibilizer. The obtained results proved that homogenous compounding of high melt viscosity UHMWPE with CNF was feasible by optimizing the melt blending processing condition in triple screw kneading extruder, which resulted in improved stiffness, a contributing factor for wear resistance.

Background An optimum restoration for reconstructing endodontically treated teeth should provide excellent marginal adaptation, high fracture resistance as well as maximum tooth structure conservation. The purpose of this study was to evaluate the marginal adaptation and fatigue resistance of different coronal restorations in endodontically treated premolars. Methods Thirty sound maxillary first premolars were endodontically treated and received MOD cavities. Teeth were randomly allocated into three groups ( n  = 10) according to the type of coronal restoration: Group R: polyethylene fibers (ribbond), fibers-reinforced composite (everX posterior) and final layer of nano-hybrid composite. Group O: indirect lithium disilicate overlay and Group C: fiber-post, resin composite restoration, and lithium disilicate crown. Marginal gap assessment was performed before and after thermocycling (5000 cycles) using stereomicroscope. Samples were subjected to stepwise-stress loading starting at 200 N, and increased by 100 N in each step until failure occurred. Statistical analysis was done by One-way ANOVA followed Tukey`s Post Hoc test for multiple comparison. Paired t test was used to compare the marginal adaptation before and after thermocycling. Survival probability was evaluated by Life table survival analysis. Failure mode analysis was performed with Chi-square test. Results Marginal gap was significantly the lowest in group R (37.49 ± 5.05) and (42.68 ± 2.38), while being the highest in group C (59.78 ± 5.67) and (71.52 ± 5.18) in before and after thermocycling respectively ( P  < 0.0001). Fatigue resistance was the highest for group O (1310.8 ± 196.7), and the lowest for group R (905.4 ± 170.51) with a significant difference between groups ( P  < 0.0001). Crown group had the highest percentage (80%) of catastrophic failure, while, overlay group exhibited the lowest (20%). Conclusions Direct restoration without cuspal coverage using ribbon fibers with short FRC provided better marginal adaptation than indirect overlays and crowns, but fatigue resistance wasn’t significantly improved. Adhesive ceramic overlays showed the best fatigue performance and the least catastrophic failure rate compared to both direct fiber-reinforced composite and indirect ceramic full coverage restorations. Clinical significance Indirect adhesive overlays are a suitable, more conservative restorative option for endodontically treated teeth than full coverage restorations, especially when tooth structure is severely compromised.

The present Bayesian network meta-analysis compared different types of polyethylene liners in total hip arthroplasty (THA) in terms of wear penetration (mm/year) and rate of revision. The type of liners compared were the crosslinked ultra-high molecular weight polyethylene (CPE/UHMWPE), Vitamin E infused highly cross-linked polyethylene (HXLPE-VEPE), modified cross-linked polyethylene (MXLPE), highly cross-linked polyethylene (HXLPE), Cross-linked polyethylene (XLPE). This study was conducted according to the PRISMA extension statement for reporting systematic reviews incorporating network meta-analyses of healthcare interventions. In June 2024, PubMed, Scopus, Embase, Google Scholar, and Cochrane databases were accessed. A time constraint was set from January 2000. All investigations which compared two or more types of polyethylene liners for THA were accessed. Only studies that clearly stated the nature of the liner were included. Data from 60 studies (37,352 THAs) were collected. 56% of patients were women. The mean age of patients was 60.0 ± 6.6 years, the mean BMI was 27.5 ± 2.0 kg/m 2 . The mean length of follow-up was 81.6 ± 44.4 months. Comparability was found at baseline between groups. XLPE and HXLPE liners in THA are associated with the lowest wear penetration (mm/year) and the lowest revision rate at approximately 7 years of follow-up.

Cell culturing methods in its classical 2D approach have limitations associated with altered cell morphology, gene expression patterns, migration, cell cycle and proliferation. Moreover, high throughput drug screening is mainly performed on 2D cell cultures which are physiologically far from proper cell functions resulting in inadequate hit-compounds which subsequently fail. A shift to 3D culturing protocols could solve issues with altered cell biochemistry and signaling which would lead to a proper recapitulation of physiological conditions in test systems. Here, we examined porous ultra-high molecular weight polyethylene (UHMWPE) as an inexpensive and robust material with varying pore sizes for cell culturing. We tested and developed culturing protocols for immortalized human neuroblastoma and primary mice hippocampal cells which resulted in high rate of cell penetration within one week of cultivation. UHMWPE was additionally functionalized with gelatin, poly-L-lysine, BSA and chitosan, resulting in increased cell penetrations of the material. We have also successfully traced GFP-tagged cells which were grown on a UHMWPE sample after one week from implantation into mice brain. Our findings highlight the importance of UHMWPE use as a 3D matrix and show new possibilities arising from the use of cheap and chemically homogeneous material for studying various types of cell-surface interactions further improving cell adhesion, viability and biocompatibility.

Previous studies have shown that increased cross-link density, reduced free radicals, and increased antioxidant grafting resulting from electron-beam irradiation at elevated temperatures improved the wear performance and the oxidative stability of vitamin E blended UHMWPE. The current study explores the impact of elevated irradiation temperature on vitamin E blended UHMWPE using X-ray. We hypothesize that the effects of temperature would be similar to those observed after electron-beam irradiation due to the relatively high dose rate of X-rays. Two X-ray doses of 80 and 100 kGy and two irradiation temperatures, that is, room temperature and 100°C were considered. The reference was Vitelene®, a vitamin E stabilized polyethylene cross-linked with 80 kGy by e-beam at 100°C. Oxidation index and oxidation induction time, as well as cross-link density, gel fraction, and trans-vinylene index, were determined, as the oxidative and network properties are decisive for the long-term implant performance. Gel fraction and oxidation induction time were significantly improved subsequently to warm irradiation in comparison with the material irradiated at room temperature. In conclusion, X-ray irradiation at elevated temperatures resulted in an increase of cross-linking and oxidative resistance of vitamin E stabilized polyethylene comparable to those of e-beam irradiated UHMWPE.

This study investigated the adsorption of methyl orange (MO), an anionic dye, on environmentally aged polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS) microplastics (MPs) to understand their interactions in aquatic environments. The MPs were characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The adsorption experiment data followed pseudo-second-order kinetics and fit well with the Langmuir and Freundlich isotherm models. The adsorption capacities of MO onto the MPs were 2.86 mg/g, 3.64 mg/g, and 3.81 mg/g for PE, PET, and PS, respectively, at a neutral pH of 7.0. The MPs combined with MO mainly through chemisorption, hydrogen bonding, and hydrophilic interaction. The optimum conditions for MO (23.41% for PE, 22.8% for PET, and 22.64% for PS) removal by the MPs were: pH 2, MO concentration of 27.5 mg/L, and MPs dose of 15.0 g/L, as determined using response surface methodology (RSM). Additionally, the presence of salt (NaCl) and humic acid (HA) competed with MO for adsorption sites on the MPs. The desorption of MO from the MPs was relatively higher in freshwater (16–30%) than in simulated seawater (12–19%). This study elucidates the interaction of MO with environmentally aged PE, PET, and PS MPs in aquatic environments, and demonstrates the transport capacity of MO dye from wastewater to freshwater, and eventually to the ocean.

The widespread use of plastics has led to an omnipresence in soils. We aim to understand whether transformation of polyethylene (PE) and polyethylene terephthalate (PET) in the atmosphere alters their surface properties which, after input of microplastics to soil, leads to an increase of reactive surfaces in soils. PE and PET particles (sieved 200–400 µm) were exposed to accelerated UV degradation. Changes in particle size and surface morphology were measured (using electron microscopy) and compared to pH-dependent variation in surface charge parameters (zeta potential and cation exchange capacity). Fourier transform infrared spectroscopy and X-ray photoemission spectroscopy detected the formation of functional groups and surface atomic composition. After 2000 hours of degradation, PE particles reduced in size from 375 ± 117 µm to 8 ± 7 µm, while PET particles showed only a slight decrease in size, from 653 ± 219 µm to 484 ± 274 µm. Reduction of particle sizes correlated with increased absolute zeta potential and a decrease of the isoelectric point. Hydrated surface charge of degraded PE after 2000 hours was unstable under alkaline conditions, related to the formation of carbonyl groups on its surface and increase in hydrophilicity. PET showed fewer surface chemical changes. Especially for degraded PE incorporated in soil, the alteration of its surface can exhibit comparatively one-tenth of the cation sorption power of clay in alkaline environments (≈7.5 vs. 77 cmol c / kg at pH 9), while degraded PET remained comparatively low (≈1.1 cmol c / kg). This study demonstrates that PE undergoes substantial physicochemical changes during UV degradation, increasing its reactivity, while PET remains relatively stable. These findings highlight the need for further studies to differentiate and understand the effects of diverse plastic types on soil ecosystems.

More than 60.000 hip arthroplasty are performed every year in Italy. Although Ultra-High-Molecular-Weight-Polyethylene remains the most used material as acetabular cup, wear of this material induces over time in vivo a foreign-body response and consequently osteolysis, pain, and the need of implant revision. Furthermore, oxidative wear of the polyethylene provoke several and severe failures. To solve these problems, highly cross-linked polyethylene and Vitamin-E-stabilized polyethylene were introduced in the last years. In in vitro experiments, various efforts have been made to compare the wear behavior of standard PE and vitamin-E infused liners. In this study we compared the in vitro wear behavior of two different configurations of cross-linked polyethylene (with and without the add of Vitamin E) vs. the standard polyethylene acetabular cups. The aim of the present study was to validate a micro X-ray computed tomography technique to assess the wear of different commercially available, polyethylene's acetabular cups after wear simulation; in particular, the gravimetric method was used to provide reference wear values. The agreement between the two methods is documented in this paper.

Background Dislocation after revision THA is a common complication. Large heads have the potential to decrease dislocation rate, but it is unclear whether they do so in revision THA. Questions/purposes We therefore determined whether a large femoral head (36 and 40 mm) resulted in a decreased dislocation rate compared to a standard head (32 mm). Methods We randomized 184 patients undergoing revision THA to receive either a 32-mm head (92 patients) or 36- and 40-mm head (92 patients) and stratified patients by surgeon. The two groups had similar baseline demographics. The primary end point was dislocation. Quality-of-life (QOL) measures were WOMAC and SF-36. The mean followup for dislocation was 5 years (range, 2–7 years); the mean followup for QOL was 2.2 years (range, 1.6–4 years). Results In the 36- and 40-mm head group, the dislocation rate was 1.1% (one of 92) versus 8.7% (eight of 92) for the 32-mm head. There was no difference in QOL outcomes between the two groups. Conclusions Our observations confirm a large femoral head (36 or 40 mm) reduces dislocation rates in patients undergoing revision THA at short-term followup. We now routinely use large heads with a highly crosslinked polyethylene acetabular liner in all revision THAs. Level of Evidence Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.