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BACKGROUND: To evaluate the flexural strength of digitally milled and printed denture base materials. METHODS: The materials tested were Lucitone 199 denture base disc (Dentsply Sirona), AvaDent denture base puck (AvaDent), KeyMill denture base disc (Keystone), Lucitone digital print denture base resin (Dentsply Sirona), Formlab denture base resin (Formlabs), and Dentca base resin II (Dentca). Sixty bar-shaped specimens of each material were prepared for flexural strength testing and were divided into five groups: control, thermocycled, fatigue cycled, and repair using two different materials. The flexural strength and modulus were tested using a 3-point bend test performed on an Instron Universal Testing Machine with a 1kN load cell. The specimens were centered under a loading apparatus with a perpendicular alignment. The loading rate was a crosshead speed of 0.5 mm/min. Each specimen was loaded with a force until failure occurred. A one-way ANOVA test was used to analyze the data, followed by Tukey's HSD test (α = 0.05). RESULTS: The milled materials exhibited higher flexural strength than the printed materials. Thermocycling and fatigue reduce the flexural strengths of printed and milled materials. The repaired groups exhibited flexural strengths of 32.80% and 30.67% of the original flexural strengths of printed and milled materials, respectively. Nevertheless, the type of repair material affected the flexural strength of the printed materials; the composite resin exhibited higher flexural strength values than the acrylic resin. CONCLUSIONS: The milled denture base materials showed higher flexural strength than the printed ones.

Asunto(s)

Resinas Acrílicas , Análisis del Estrés Dental , Bases para Dentadura , Resistencia Flexional , Ensayo de Materiales , Resinas Acrílicas/química , Materiales Dentales/química , Módulo de Elasticidad , Diseño de Dentadura , Propiedades de Superficie , Estrés Mecánico , Docilidad , Humanos , Reparación de la Dentadura , Impresión Tridimensional , Diseño Asistido por Computadora

RESUMEN

OBJECTIVES: To evaluate the mechanical properties of root canal dentin treated with sodium hypochlorite (NaOCl) in combination with hydroxyethylidene diphosphonic acid (HEDP) or ethylenediaminetetraacetic acid (EDTA). METHODS: For testing fracture resistance, 45 single-rooted teeth were instrumented and irrigated with NaOCl/HEDP, NaOCl/EDTA, or distilled water. Fifteen untreated teeth served as control. After obturation, specimens from the experimental groups were thermocycled, dynamically-loaded, and then statically-loaded in a universal testing machine until failure. For flexural strength analysis, 15 teeth were instrumented and irrigated with NaOCl/HEDP or NaOCl/EDTA. Root segments were sectioned into dentin bars and tested for flexural strength using a universal testing machine. For microhardness evaluation, 20 teeth were instrumented and irrigated with NaOCl/HEDP or NaOCl/EDTA. Dentin disks from the coronal-third of each root segment were prepared, one before and one after irrigation, for microhardness testing with a Knoop hardness tester. RESULTS: The highest fracture resistance was recorded in the untreated group, and the lowest in the EDTA group. Although the HEDP group had higher fracture resistance than the EDTA group, the distilled water group demonstrated even greater fracture resistance than the HEDP group. Specimens treated with HEDP had significantly higher flexural strength and microhardness values when compared with those treated with EDTA. CONCLUSION: The fracture resistance, flexural strength, and microhardness of root canal dentin were higher when root canals were irrigated with NaOCl/HEDP, when compared with NaOCl/EDTA. CLINICAL SIGNIFICANCE: Irrigating root canals with NaOCl combined with HEDP significantly improves the mechanical integrity of root canal dentin compared to the use of NaOCl with EDTA.

Asunto(s)

Quelantes , Dentina , Ácido Edético , Dureza , Ensayo de Materiales , Irrigantes del Conducto Radicular , Hipoclorito de Sodio , Dentina/efectos de los fármacos , Hipoclorito de Sodio/farmacología , Humanos , Ácido Edético/farmacología , Irrigantes del Conducto Radicular/farmacología , Quelantes/farmacología , Estrés Mecánico , Ácido Etidrónico/farmacología , Cavidad Pulpar/efectos de los fármacos , Resistencia Flexional , Análisis del Estrés Dental , Preparación del Conducto Radicular/métodos , Fracturas de los Dientes/prevención & control , Raíz del Diente/efectos de los fármacos , Docilidad , Temperatura , Obturación del Conducto Radicular/métodos

RESUMEN

BACKGROUND: Low mechanical properties are the main limitation of glass ionomer cements (GICs). The incorporation of elastomeric micelles is expected to enhance the strength of GICs without detrimentally affecting their physical properties and biocompatibility. This study compared the chemical and mechanical properties, as well as the cytotoxicity, of elastomeric micelles-containing glass ionomer cement (DeltaFil, DT) with commonly used materials, including EQUIA Forte Fil (EF), Fuji IX GP Extra (F9), and Ketac Molar (KT). METHOD: Powder particles of GICs were examined with SEM-EDX. Setting kinetics were assessed using ATR-FTIR. Biaxial flexural strength/modulus and Vickers surface microhardness were measured after immersion in water for 24 h and 4 weeks. The release of F, Al, Sr, and P in water over 8 weeks was analyzed using a fluoride-specific electrode and ICP-OES. The toxicity of the material extract on mouse fibroblasts was also evaluated. RESULTS: High fluoride levels in the powder were detected with EF and F9. DT demonstrated an initial delay followed by a faster acid reaction compared to other cements, suggesting an improved snap set. DT also exhibited superior flexural strength than other materials at both 24 h and 4 weeks but lower surface microhardness (p < 0.05). EF and F9 showed higher release of F, Al, and P than DT and KT. There was no statistically significant difference in fibroblast viability among the tested materials (p > 0.05). CONCLUSIONS: Elastomeric micelles-containing glass ionomer cement (DT) exhibited satisfactory mechanical properties and cytocompatibility compared with other materials. DT could, therefore, potentially be considered an alternative high-strength GIC for load-bearing restorations.

Asunto(s)

Elastómeros , Fibroblastos , Resistencia Flexional , Cementos de Ionómero Vítreo , Dureza , Ensayo de Materiales , Micelas , Cementos de Ionómero Vítreo/toxicidad , Cementos de Ionómero Vítreo/química , Animales , Ratones , Fibroblastos/efectos de los fármacos , Elastómeros/química , Elastómeros/toxicidad , Aluminio/química , Fluoruros/química , Estroncio/química , Cemento de Policarboxilato/química , Cemento de Policarboxilato/toxicidad , Supervivencia Celular/efectos de los fármacos , Microscopía Electrónica de Rastreo , Propiedades de Superficie , Docilidad , Cinética , Espectroscopía Infrarroja por Transformada de Fourier , Estrés Mecánico , Factores de Tiempo , Materiales Biocompatibles/química

RESUMEN

BACKGROUND: In dentistry, glass-ionomer cements (GICs) are extensively used for a range of applications. The unique properties of GIC include fluoride ion release and recharge, chemical bonding to the tooth's hard tissues, biocompatibility, a thermal expansion coefficient like that of enamel and dentin, and acceptable aesthetics. Their high solubility and poor mechanical qualities are among their limitations. E-glass fibers are generally utilized to reinforce the polymer matrix and are identified by their higher silica content. OBJECTIVES: The purpose of the study was to assess the impact of adding (10 wt% and 20 wt%) silane-treated E-glass fibers to traditional GIC on its mechanical properties (compressive strength, flexural strength, and surface hardness) and solubility. METHODS: The characterization of the E-glass fiber fillers was achieved by XRF, SEM, and PSD. The specimens were prepared by adding the E-glass fiber fillers to the traditional GIC at 10% and 20% by weight, forming two innovative groups, and compared with the unmodified GIC (control group). The physical properties (film thickness and initial setting time) were examined to confirm operability after mixing. The evaluation of the reinforced GIC was performed by assessing the compressive strength, flexural strength, hardness, and solubility (n = 10 specimens per test). A one-way ANOVA and Tukey tests were performed for statistical analysis (p ≤ 0.05). RESULTS: The traditional GIC showed the least compressive strength, flexural strength, hardness, and highest solubility. While the GIC reinforced with 20 wt% E-glass fibers showed the highest compressive strength, flexural strength, hardness, and least solubility. Meanwhile, GIC reinforced with 10 wt% showed intermediate results (P ≤ 0.05). CONCLUSION: Using 20 wt% E-glass fiber as a filler with the traditional GIC provides a strengthening effect and reduced solubility.

Asunto(s)

Fuerza Compresiva , Resistencia Flexional , Cementos de Ionómero Vítreo , Vidrio , Dureza , Ensayo de Materiales , Solubilidad , Cementos de Ionómero Vítreo/química , Vidrio/química , Propiedades de Superficie , Silanos/química , Microscopía Electrónica de Rastreo , Análisis del Estrés Dental , Docilidad , Humanos

RESUMEN

PURPOSE: To date, no study has evaluated effects of varying brightness settings on image quality from flexible ureteroscopes submerged in saline. The aim was to evaluate blackout and whiteout occurrences in an in-vitro kidney calyx model. MATERIAL AND METHODS: We evaluated a series of contemporary flexible ureteroscopes including the Storz Flex-Xc and Flex-X2s, Olympus V3 and P7, Pusen 7.5F and 9.2F, as well as OTU WiScope using a 3D-printed enclosed pink in-vitro kidney calyx model submerged in saline. Endoscopic images were captured with ureteroscope tip placed at 5 mm,10 mm and 20 mm distances. The complete range of brightness settings and video capture modes were evaluated for each scope. Distribution of brightness on a grayscale histogram of images was analyzed (scale range 0 to 255). Blackout and whiteout were defined as median histogram ranges from 0 to 35 and 220 to 255, respectively (monitor image too dark or too bright for the human eye, respectively). RESULTS: Blackout occurred with the P7, Pusen 7.5F, 9.2F and WiScope at all distances, and V3 at 20 mm - with lowest brightness settings. Whiteout occurred with Flex-X2s, V3 and P7 at 5 mm and 10 mm, as well as with V3 and P7 at 20 mm - mostly with highest brightness settings. The Flex-Xc had neither blackout nor whiteout at all settings and distances. CONCLUSION: Blackout or whiteout of images is an undesirable property that was found for several scopes, possibly impacting diagnostic and therapeutic purposes during ureteroscopy. These observations form a guide to impact a urologist's choice of instruments and settings.

Asunto(s)

Ureteroscopios , Ureteroscopía , Humanos , Diseño de Equipo , Iluminación , Docilidad , Cálices Renales

RESUMEN

INTRODUCTION: Disposable (single-use) flexible ureteroscopes are alternatives to reusable ureteroscopes. With their superior surgical efficacy and safety in the presence of upper urinary calculi, disposable ureteroscopes aim to overcome the main limitations of conventional reusable ureteroscopes. However, studies on the performance of the most recently developed models of single-use flexible ureteroscopes are scarce. This study aimed to compare the in vitro performance of several recently introduced, single-use, flexible ureteroscopes. METHODS: Five disposable flexible ureteroscopes were tested in vitro to evaluate their mechanical and optical characteristics. To this end, their degrees of deflection, irrigation flow rates, and image qualities were investigated. The models examined were Innovex US31-B12, OTU-100RR, Redpine RP-U-C12, Sciavita SUV-2A-B, and Seplou URS3016E. Their performance was also compared with that of a reusable flexible ureteroscope, Olympus URV-F. RESULTS: The OTU device had the highest degrees of deflection and the smallest loop diameter of the disposable ureteroscopes. The single-use ureteroscopes had identical image resolutions at a distance of 1 cm. The Innovex and Redpine devices had the best color representation. CONCLUSIONS: Of the tested disposable ureteroscopes, the OTU device had the best mechanical attributes, given its small loop diameter, high deflection angles, and low irrigation flow loss. As to their optical properties, the resolutions of all 5 single-use models were identical at an image distance of 1 cm.

Asunto(s)

Equipos Desechables , Diseño de Equipo , Ureteroscopios , Humanos , Fenómenos Ópticos , Fenómenos Mecánicos , Docilidad , Ensayo de Materiales , Ureteroscopía/instrumentación

RESUMEN

PURPOSE: This study investigated the impact of reducing the oxygen concentration via nitrogen injection during the postcuring process of 3D-printed dental materials. MATERIALS AND METHODS: Resin specimens for dental crown and bridge (15-mm diameter, both 1-mm and 2-mm heights) were 3D-printed and rinsed. Subsequently, the postcuring process was conducted on nine groups categorized according to atmospheric conditions within the curing device (20% [control], 10%, and 5% oxygen) and curing times (10, 15, and 20 minutes). Surface roughness was measured using a gloss meter. Surface polymerization was confirmed through Fourier-transform infrared spectroscopy (FT-IR) analysis, and the flexural strength and elastic modulus of the specimens were measured using a universal testing machine. Water absorption and solubility were determined according to Inernational Organization for Standardization (ISO) standards. All evaluation criteria were statistically analyzed using one-way ANOVA and Tukey's post hoc test based on oxygen concentration. RESULTS: The elastic modulus did not show statistically significant differences in all groups. However, compared to the control group, the flexural strength, degree of conversion, and gloss significantly increased in the groups with decreased oxygen concentrations. Conversely, water solubility and water absorption significantly decreased in a few groups with reduced oxygen concentration. CONCLUSIONS: Reducing oxygen concentration through nitrogen injection during the postcuring process of 3D printing enhances the suitability of the dental prosthetic materials. The significant increase in flexural strength can particularly enhance the utility of these materials in dental prosthetics.

Asunto(s)

Impresión Tridimensional , Agua , Espectroscopía Infrarroja por Transformada de Fourier , Ensayo de Materiales , Docilidad , Agua/química , Nitrógeno , Resinas Sintéticas , Propiedades de Superficie

RESUMEN

Objective: To report the initial results of an randomized clinical trail comparing the safety and efficacy between 7.5F and 9.2F flexible ureteroscope (FUS) in the management of renal calculi <2 cm. Materials and Methods: Eighty patients were enrolled and received retrograde intrarenal surgery (RIRS) with a different size FUS. The operation results and complications were compared. Results: Two cases in the 7.5F group and four cases in the 9.2F group failed to insert the 12/14F ureteral access sheath (UAS), respectively, and no significant difference (p = 0.396) was noted. However, 10/12F UAS was inserted in the 7.5F group, but not available in the 9.2F group, and thus, the 10/12F UAS inserting rate in the 7.5F group was higher than in the 9.2F group (100% vs 0%, p = 0.014), and the UAS insertion failure rate in 9.2F group was higher than in the 7.5F group (10% vs 0%, p = 0.040). The operation time in 7.5F group was shorter than the 9.2F group (35.60 ± 7.86 vs 41.05 ± 8.14, p = 0.003). Less irrigation was required in 7.5F group (813.93 ± 279.47 mL vs 1504.18 ± 385.31 mL, p = 0.000). The postoperative fever rate in 9.2F group was higher than 7.5F group (20% vs 5%, p = 0.043). There was no significant difference in sepsis (0% vs 2.5%, p = 0.314) between the two groups. No significant difference was noted in hospital stay (0.93 ± 0.49 days vs 1.14 ± 0.64 days, p = 0.099) between the two groups. The final stone-free rate (SFR) in 7.5F group was higher than 9.2F group (95% vs 80%, p = 0.043). Conclusion: The latest 7.5F mini FUS was a reliable instrument in RIRS to keep a good visualization with low requirement of irrigation, low postoperative infection complication, and also a high SFR when compared with the conventional 9.2F FUS. Clinical Trial Registration: NCT05231577.

Asunto(s)

Cálculos Renales , Ureteroscopios , Humanos , Masculino , Femenino , Persona de Mediana Edad , Cálculos Renales/cirugía , Adulto , Riñón/cirugía , Resultado del Tratamiento , Complicaciones Posoperatorias/etiología , Docilidad , Anciano

RESUMEN

Epitranscriptomic mRNA modifications affect gene expression, with their altered balance detected in various cancers. YTHDF proteins contain the YTH reader domain recognizing the m6A mark on mRNA and represent valuable drug targets. Crystallographic structures have been determined for all three family members; however, discrepancies are present in the organization of the m6A-binding pocket. Here, we present new crystallographic structures of the YTH domain of YTHDF1, accompanied by computational studies, showing that this domain can exist in different stable conformations separated by a significant energetic barrier. During the transition, additional conformations are explored, with peculiar druggable pockets appearing and offering new opportunities for the design of YTH-interfering small molecules.

Asunto(s)

Proteínas de Unión al ARN , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Docilidad , ARN Mensajero/química , ARN Mensajero/metabolismo , Conformación Molecular

RESUMEN

A prática do Tai Chi Pai Lin é benéfica tanto para a saúde do corpo quanto para a mente.

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Movimiento , Naturaleza , Docilidad

RESUMEN

This study aims at evaluating and developing an environmental-friendly and sulfur-free cured ethylene propylene diene monomer (EPDM) composites. Silane grafted EPDM (SiEPDM) composites incorporated with silica is prepared via a solvent-free, one-step reactive mixing process. The silane grafting and silica filler bonding are characterized using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The mechanical properties of the developed composites are examined. The fracture morphology is observed using an environmental scanning electron microscopy. The rheology and thermomechanical properties are evaluated by using a rotational rheometer and dynamic mechanical analyzer. Notably, a robust bonding between silica and the grafted silane is established, yielding a crosslinking network within the composite structure. This phenomenon is substantiated by the observed gel efficiency and rheology behavior. Consequently, a pronounced augmentation of up to 75% in tensile strength and 29% in tear strength are observed in the optimized SiEPDM-silica composites, distinguishing them from their EPDM-silica counterparts. The introduction of paraffin oil contributes to enhanced processability; however, it is concomitant with a reduction in gel efficiency and associated mechanical properties. Furthermore, subsequent UV weathering test unveils that the SiEPDM-silica composites exhibit the highest levels of residual tensile strength and modulus, indicative of their exceptional UV stability.

Asunto(s)

Elastómeros , Metacrilatos , Silanos , Metacrilatos/química , Silanos/química , Resinas Compuestas/química , Dióxido de Silicio/química , Docilidad , Ensayo de Materiales , Etilenos

RESUMEN

OBJECTIVES: The present investigation is aimed at evaluating the effect of styrene butadiene rubber, glass fibre, nylon fibre and hybrid reinforcement of glass and nylon fibre with 0.5 and 1.0 wt% on the impact, flexural, and compressive properties. METHODS: A total of 19 groups were formed, including one control group and 18 study groups. All specimens were fabricated according to the standards and tests were performed. The enhancement of strengths were characterised by using scanning electron micrographs, FTIR results, XRD, and DMA tests. The degradability was studied using TGA/DTA analysis. The results were analysed using one-way ANOVA and Dunnett's post hoc multiple comparison test at p ≤ 0.05. RESULTS: The maximum impact, flexural, and compressive strength were found to be 3.234 ± 0.202 kJ/m2, 70.07 ± 0.7 MPa, and 84.929 ± 0.85 MPa for hybrid reinforcement of 0.5 wt% nylon fiber and 0.5 wt% glass fiber with 1.0 wt% of styrene butadiene rubber (SBR) mixed PMMA denture base material. Statistical analysis shows that the maximum mean impact strength, flexural strength, and compressive strength are about 84%, 58%, and 67% higher than the pure PMMA (control group). The maximum flexural modulus and compressive modulus are 914.4 MPa and 407.847 MPa for denture base material made of 1.0 wt% SBR, 1.0 wt% nylon fiber, 0.5 wt% glass fiber, and 0.5 wt% SBR, 0.5 wt% nylon fiber, respectively. The storage moduli of 1.0 wt% SBR, 1.0 wt% nylon fiber, and 0.5 wt% glass fiber-reinforced denture base material and pure PMMA are 0.096 and 0.422 at 79 °C, respectively, which indicates significant crosslinking of fiber and PMMA. The failure surfaces are characterized by a homogeneous distribution of fiber with increased surface roughness and fiber pullout, strong bonding, and well-dispersed SBR.

Asunto(s)

Nylons , Polimetil Metacrilato , Goma , Bases para Dentadura , Butadienos , Ensayo de Materiales , Docilidad , Vidrio

RESUMEN

PURPOSE: Inappropriate stent-graft (SG) flexibility has been frequently associated with endovascular aortic repair (EVAR) complications such as endoleaks, kinks, and SG migration, especially in tortuous arteries. Stents derived from auxetic unit cells have shown some potential to address these issues as they offer an optimum trade-off between radial stiffness and bending flexibility. METHODS: In this study, we utilized an established finite element (FE)-based approach to replicate the mechanical response of a SG iliac limb derived from auxetic unit cells in a virtual tortuous iliac aneurysm using a combination of a 180° U-bend and intraluminal pressurization. This study aimed to compare the mechanical performance (flexibility and durability) of SG limbs derived from auxetic unit cells and two commercial SG limbs (Z-stented SG and circular-stented SG models) in a virtual tortuous iliac aneurysm. Maximal graft strain and maximum stress in stents were employed as criteria to estimate the durability of SGs, whereas the maximal luminal reduction rate and the bending stiffness were used to assess the flexibility of the SGs. RESULTS: SG limbs derived from auxetic unit cells demonstrated low luminal reduction (range 4-12%) with no kink, in contrast to Z-stented SG, which had a kink in its central area alongside a high luminal reduction (44%). CONCLUSIONS: SG limbs derived from auxetic unit cells show great promise for EVAR applications even at high angulations such as 180°, with acceptable levels of durability and flexibility.

Asunto(s)

Implantación de Prótesis Vascular , Prótesis Vascular , Procedimientos Endovasculares , Análisis de Elementos Finitos , Modelos Cardiovasculares , Diseño de Prótesis , Stents , Estrés Mecánico , Humanos , Procedimientos Endovasculares/instrumentación , Implantación de Prótesis Vascular/instrumentación , Aneurisma Ilíaco/cirugía , Aneurisma Ilíaco/fisiopatología , Aneurisma Ilíaco/diagnóstico por imagen , Ensayo de Materiales , Falla de Prótesis , Docilidad , Simulación por Computador

RESUMEN

PURPOSE: To evaluate the effect of firing temperature and heating rate on the volumetric shrinkage, translucency, flexural strength, hardness, and fracture toughness of a zirconia veneering ceramic. MATERIAL AND METHODS: Zirconia veneering ceramic specimens (N = 45) with varying final temperatures (730 °C, 750 °C, and 770 °C) and heating rates (70 °C/min, 55 °C/min, and 40 °C/min) were fabricated (n = 5). Each specimen's shrinkage, translucency, flexural strength, hardness, and fracture toughness were determined. Two-way analysis of variance, Scheffé test, and Pearson's correlation analysis were used to evaluate data (α = 0.05). RESULTS: The shrinkage (44.9 ± 3.1-47.5 ± 1.6 vol%) and flexural strength (74.1 ± 17.4-107.0 ± 27.1 MPa) were not affected by tested parameters (P ≥ 0.288). The interaction between the main factors affected the translucency, hardness, and fracture toughness of the specimens (P ≤ 0.007). Specimens with 770 °C final temperature and 70 °C/min heating rate had the lowest (21.8 ± 3.2 %) translucency (P ≤ 0.039). The hardness ranged between 4.98 ± 0.51 GPa (730 °C; 70 °C/min) and 5.60 ± 0.37 GPa (770 °C; 70 °C/min). Fracture toughness ranged between 0.54 ± 0.04 MPa√m and 0.67 ± 0.08 MPa√m with the highest values for specimens fired at 730 °C with 70 °C/min (P ≤ 0.001). There was a positive correlation between translucency and hardness (r = 0.335, P = 0.012), and a negative correlation between fracture toughness and all parameters other than shrinkage (translucency: r = -0.693/P < 0.001, flexural strength: r = -0.258/P = 0.046, hardness: r = -0.457/P < 0.001). CONCLUSIONS: Heating rate and final temperature should be considered while fabricating veneered zirconia restorations with tested ceramic as they affected the translucency, hardness, and fracture toughness.

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Calefacción , Circonio , Temperatura , Ensayo de Materiales , Docilidad , Propiedades de Superficie , Cerámica , Porcelana Dental

RESUMEN

OBJECTIVES: Currently used thiourea-based two-component dental materials may release bitter compounds if they are not properly cured. To address this issue, the objective of this study was to evaluate the potential of acylthiourea oligomers as reducing agents for the development of self-cure composites. METHODS: Acylthiourea oligomers ATUO1-3 were synthesized via cotelomerization of the acylthiourea methacrylate ATU1 with butyl methacrylate. They were characterized by 1H NMR spectroscopy and size exclusion chromatography. Self-cure composites based on the redox initiator system cumene hydroperoxide/acylthiourea oligomer/copper(II) acetylacetonate were formulated. The flexural strength and modulus were measured using a three-point bending setup. The double bond conversions were determined using NIR spectroscopy. The working time of each self-cure composite was measured using an oscillating rheometer. Leaching experiments using light-cure composites were performed in DMSO-d6. RESULTS: Acylthiourea oligomers ATUO1-3 were successfully synthesized in good yields. Both the oligomer molecular weight and the amount of thiourea groups were varied. Self-cure composites containing ATUO1 or ATUO2 as reducing agents exhibited excellent mechanical properties and high double-bond conversions. The amounts of reducing agent, cumene hydroperoxide and copper(II) acetylacetonate were shown to have a significant impact on the working time. Moreover, a correlation between flexural modulus and the amount of metal salt was clearly established. Self-cure composites containing the oligomer ATUO1 exhibited a longer working time than materials containing ATU1 or acetylthiourea. Contrary to acetylthiourea, ATUO1 was not able to leach out of light-cured composites. SIGNIFICANCE: Acylthiourea oligomers are promising reducing agents for the formulation of two-component dental materials that do not induce a bitter taste in mouth.

Asunto(s)

Resinas Compuestas , Sustancias Reductoras , Resinas Compuestas/química , Ensayo de Materiales , Metacrilatos/química , Tiourea , Materiales Dentales/química , Docilidad , Bisfenol A Glicidil Metacrilato/química , Ácidos Polimetacrílicos/química

RESUMEN

OBJECTIVE: The main aim of the current work was to develop dental acrylic-based composites with protein-repellent and antibacterial properties by using surface-modified silica nanoparticles. The effects of surface modification of silica nanoparticles in protein-repellent and antibacterial activity and mechanical properties of dental composites including flexural strength, flexural modulus, and hardness were discussed. METHODS: The surface of silica nanoparticles was first chemically treated with 3-methacryloxypropyltrimethoxysilane (MPS) as a coupling agent and then with poly(ethylene glycol) (PEG) bonded to MPS. Dental acrylic-based composites were prepared with mass fractions of 10, 15, 20, 30, and 40 % of PEG-modified MPS-silica nanoparticles (PMS). The chemical surface modification of silica nanoparticles with MPS and PEG was confirmed by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). RESULTS: The dental composite containing 20 wt% PMS nanoparticles could reduce the protein adsorption by 28 % as compared with a composite containing 20 wt% MPS-modified silica. The antibacterial test indicated that the PMS nanoparticles can significantly reduce the adhesion of Streptococcus mutans and the biofilm formation on the surface of dental composites. It was found that the flexural strength increased by increasing the PMS nanoparticles from 0 to 20 wt% and then decreased by the incorporation of higher percentages of these nanoparticles. Also, with increasing the weight percentage of PMS nanoparticles, the elastic and the flexural modulus and the hardness of resin nanocomposites were increased. SIGNIFICANCE: In the current work, for the first time, dental resin composites containing PEG were prepared with excellent protein-repellent and antibacterial properties.

Asunto(s)

Resistencia Flexional , Nanocompuestos , Polietilenglicoles/farmacología , Polietilenglicoles/química , Resinas Compuestas/farmacología , Resinas Compuestas/química , Ácidos Polimetacrílicos/química , Dióxido de Silicio/farmacología , Dióxido de Silicio/química , Silanos/farmacología , Silanos/química , Docilidad , Ensayo de Materiales , Nanocompuestos/química , Antibacterianos/farmacología , Propiedades de Superficie

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Rinoplastia , Humanos , Rinoplastia/métodos , Ácido Hialurónico , Docilidad , Nariz/cirugía

RESUMEN

STATEMENT OF PROBLEM: Studies on the effects of postprocessing conditions on the physical properties, degree of conversion (DC), and biocompatibility of denture bases produced by digital light processing are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effects of the atmosphere during postpolymerization and of postpolymerization time on the flexural strength, Vickers hardness, DC, cytotoxicity, and residual monomer content of denture bases. MATERIAL AND METHODS: Six different groups of bar- and disk-shaped specimens from the denture base resin were produced, considering 2 different atmospheres (air and nitrogen) and 3 different postpolymerization times (5, 10, and 20 minutes). To determine the physical properties, the flexural strength and Vickers hardness were measured. Fourier transform infrared spectrometry was used to calculate DC. Cytotoxicity was assessed from the effect on human gingival fibroblasts. The residual monomer content was determined by using high-performance liquid chromatography. Based on the normality test by the Shapiro-Wilk method, a nonparametric factorial analysis of variances was conducted (α=.05). RESULTS: A significant interaction was detected between the atmosphere and postpolymerization time for hardness (P<.001) but no interaction for strength, DC, or cytotoxicity (P=.826, P=.786, and P=.563, respectively). Hardness was significantly affected by the postpolymerization time in the groups with the nitrogen atmosphere (P<.001). DC was significantly affected by the atmosphere (P=.012), whereas strength and cytotoxicity were not (P=.500 and P=.299, respectively). Cytotoxicity was significantly affected by the postpolymerization time (P<.001), but strength and DC were not (P=.482 and P=.167, respectively). Residual monomers were not detected after ≥10-minute postpolymerization time. CONCLUSIONS: The atmosphere significantly affected hardness and DC, whereas the postpolymerization time significantly affected hardness, DC, cytotoxicity, and residual monomer content. Denture bases produced in a nitrogen atmosphere and with the 10-minute postpolymerization time showed sufficient hardness, DC, and no cytotoxicity.

Asunto(s)

Resinas Acrílicas , Bases para Dentadura , Humanos , Resinas Acrílicas/química , Docilidad , Ensayo de Materiales , Resistencia Flexional , Dureza , Propiedades de Superficie

RESUMEN

Introducción: El rodillo de espuma o Foam Roller (FR) es un instrumento de liberación miofascial autoinducida, para aplicarpresión de forma directa sobre la musculatura diana. FR es ampliamente empelado por deportistas como herramienta deauto-masaje. Objetivo: Evaluar la evidencia actual sobre el impacto del FR, sobre el sistema musculoesquelético, en deportistas, tratandode identificar los mecanismos que influyen sobre los tejidos miofasciales.Material y método: Basándonos en las directrices de los Elementos de Información Preferidos para Revisiones Sistemáticas yMetaanálisis (PRISMA), revisamos sistemáticamente estudios indexados en Web of Science, Cochrane y PubMed, para evaluarlos efectos del FR en el rango articular de movimiento (ROM), la flexibilidad, la fuerza y el dolor muscular de inicio retardado(DOMS) en deportistas de alto rendimiento. Se incluyeron artículos originales publicados desde el 2018 hasta el 30 de septiembre de 2022, con diseño de ensayo controlado o pre-post intervención, en los que se comparó la intervención de FR conun grupo control. Se utilizó la escala PEDro para evaluar de la calidad metodológica.Resultados: Entre los 141 registros identificados en la búsqueda, un total de 10 estudios cumplieron los criterios de inclusióny exclusión. En general, el uso de FR, en los deportistas de alto rendimiento, mostró mejoras significativas sobre el ROM yflexibilidad, y efectos notablemente beneficiosos sobre el DOMS y la fuerza, sin efectos adversos en el tejido miofascial. El FRpuede actuar mejorando la arquitectura tisular miofascial, atenuando el efecto inflamatorio y nociceptivo. Conclusión: El uso FR, parece seguro, es un instrumento efectivo para la mejora de las cualidades físicas de movilidad, fuerzay flexibilidad, y disminuir el DOMS incrementando del rendimiento deportivo.(AU)

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Introduction: The Foam Roller (FR) is a self-induced myofascial release instrument to apply pressure directly on the targetmusculature. FR is widely used by athletes as a self-massage tool. Objective: We evaluate the current evidence on the impact of FR on the musculoskeletal system in athletes, trying to identifythe mechanisms that influence myofascial tissues.Material and method: Based on the Preferred Reporting Item Guidelines for Systematic Reviews and Meta-Analyses (PRISMA),we systematically reviewed studies indexed in Web of Science, Cochrane, and PubMed to evaluate the effects of FR on jointrange of motion (ROM), flexibility, strength, and delayed onset muscle soreness (DOMS) in high-performance athletes. Originalarticles published from 2018 through September 30, 2022, with controlled trial or pre-post intervention design, in which theFR intervention was compared to a control group, were included. The PEDro scale was used to assess methodological quality. Results: Among the 141 records identified in the search, a total of 10 studies met the inclusion and exclusion criteria. Ingeneral, the use of FR, in high performance athletes, showed significant improvements on ROM and flexibility, and markedlybeneficial effects on DOMS and strength, with no adverse effects on myofascial tissue. FR may act by improving myofascialtissue architecture, attenuating the inflammatory and nociceptive effect. Conclusion: The use of FR seems to be safe; it is an effective tool for the improvement of the physical qualities of mobility,strength, and flexibility, and to decrease DOMS and increase sports performance.(AU)

Asunto(s)

Humanos , Masculino , Femenino , Adulto , Rango del Movimiento Articular , Mialgia , Fuerza Muscular , Atletas , Docilidad , Dolor , Deportes , Medicina Deportiva , Psicología del Deporte , Síndromes del Dolor Miofascial

Asunto(s)

Ingeniería Genética , Plantas , Docilidad , Plantas/genética , Plantas/metabolismo , Caminata