Methacrylate Research Articles

Comparative study of two biocomposites: Effect of date stone flour treated with potassium permanganate as a filler on the morphological and elastic properties

The paper deals with the effect of date stone flour (DSF) as a filler on the elastic properties of biocomposites based on two different matrices, namely, polymethyl methacrylate (PMMA) and green epoxy resin (GER). Potassium permanganate treatment was applied to improve the surface properties of the DSF filler. Fourier transform infrared spectrotroscopy was used to analyze the chemical changes of the functional groups in the untreated DSF and the permanganate treated DSF filler. Different filler content of 10, 20, and 30 wt%, respectively, were used to obtain PMMA/DSF and GER/DSF biocomposites. The elastic properties, namely, longitudinal modulus, shear modulus, bulk modulus, Young’s modulus of elasticity, Poisson ratio, ultrasonic micro-hardness, and acoustic impedance of the biocomposites were determined using the ultrasonic through-transmission method. In addition, the morphology was studied using optical microscopy and scanning electron microscopy. Fourier transform infrared spectrotroscopy analysis results revealed the success of the permanganate treatment. The elastic properties of PMMA/DSF biocomposites were decreased, while an improvement of these properties is observed for GER/DSF biocomposites. Morphological results showed the presence of pores and cracks in the PMMA/DSF biocomposites, which is attributed to poor interfacial adhesion between the DSF filler and the PMMA matrix. However, fewer defects were observed in the GER/DSF biocomposites, which is due to better interfacial adhesion between the DSF filler and the GER matrix.

Mechanical Properties, Cytotoxicity, and Fluoride Ion Release Capacity of Bioactive Glass-Modified Methacrylate Resin Used in Three-Dimensional Printing Technology.

Background: Clinically, three-dimensional (3D) printing technology is becoming a popular and efficient dental processing technology. Recently, there has been an increasing demand for dental materials that exhibit bioactive properties. The present study aimed to evaluate the mechanical properties, cytotoxicity, and fluoride ion release capacity of 3D-printed dental resins modified with bioactive glass. Materials and methods: The resin FotoDent splint used in the production of removable orthodontic splints, was modified by the addition of two types of bioactive glasses that are capable of releasing fluoride ions. The novel materials used for the production of dental splints were examined for their mechanical, physical, and biological properties (fracture resistance, sorption, solubility, elution of nonpolymeric substances, and release of fluoride ions over time) and cytotoxic effects on cell cultures. Results: Initially, the fracture toughness of the 3D-printed resin was found to be 55 MPa, but after modification with glass, the resistance was reduced to about 50 MPa. Sorption and solubility values of the materials (19.01 ÷ 21.23 µg/mm3 and 0.42 ÷ 1.12 µg/mm3, respectively) complied with the safety limits imposed by ISO standard. Modified resins were capable of releasing fluoride ions, and the maximum releasing effect was observed after 14 days of incubation. Both the modified resins, after four days of contact with human gingival fibroblasts, exhibited moderate cytotoxic properties. Conclusions: The experimental results showed that modification of methacrylate resin, used in 3D printing technology, with bioactive glasses produces novel dental materials that possess desirable bioactive properties. The findings of this study indicate the potential ability of modified polymethacrylate resins to release fluoride ions in the oral cavity environment. The modified materials are characterized with a moderate decrease in physical properties and mild cytotoxicity on direct contact with human fibroblasts.

Evaluation of Flexural Strength of Autopolymerizing Polymethyl Methacrylate and Bis-acrylic Composite Provisional Restorative Resins Reinforced with Bamboo Fibers: An In Vitro Study

Evaluation of Flexural Strength of Autopolymerizing Polymethyl Methacrylate and Bis-acrylic Composite Provisional Restorative Resins Reinforced with Bamboo Fibers: An In Vitro Study

Influence of polymer initiators in light guiding in a cyanobacterium incorporated (poly)-methyl methacrylate matrix

This letter investigates the luminescence property of a cyanobacterium, Arthospira platensis (spirulina) in an acrylic polymer medium. We fabricated 5 mm thick rectangular sheets by incorporating this photosynthetic organism in (Poly)-Methyl Meth Acrylate (PMMA) for waveguide applications in Luminescent Solar Concentrators (LSCs). Meanwhile, during polymerization, the use of the benzoyl peroxide initiator had a notable effect on the optical property of the pigment-protein. We recorded an enhanced fluorescence emission of the sheet fabricated in the peroxide environment. Emission efficiency is 4.09% more than that in an azo- environment. This is due to the anti-oxidant property of spirulina’s pigment-protein, which absorbs the oxygen radicals produced by the peroxide initiator.

Immediate and interim prosthodontic management of post-surgical maxillectomy patient using obturator prosthesis: A case report

This clinical report describes a comprehensive prosthodontic treatment of a young patient diagnosed with squamous cell carcinoma in hard palate. The treatment procedures included surgical removal of the tumor, immediate surgical plate and interim obturator. The surgical plate and interim prosthesis were fabricated using conventional polymethyl methacrylate resin material with retention derived from wrought wire clasps to the remaining natural teeth. The follow-up system revealed satisfactory results with no deterioration in the prosthesis.

The Effect of Salinized Nano ZrO2 Particles on the Microstructure, Hardness, and Wear Behavior of Acrylic Denture Tooth Nanocomposite.

The wear of acrylic denture teeth is a serious problem that can change the vertical dimensions of dentures. This study evaluates the effect of adding salinized nano ZrO2 particles on the microstructure, hardness, and wear resistance of acrylic denture teeth. Heat polymerizing polymethyl methacrylate resin was mixed with salinized ZrO2 at concentrations of 5 wt.% and 10 wt.%. Acrylic resin specimens without filler addition were used as a control group. SEM/EDS analyses were performed and the Vickers’ hardness was evaluated. Two-body wear testing was performed using a chewing simulator with a human enamel antagonist. After subjecting the samples to 37,500 cycles, both height loss and weight loss were used to evaluate the wear behavior. The microstructural investigation of the reinforced-denture teeth indicates sound nanocomposite preparation using the applied regime without porosity or macro defects. The addition of zirconium oxide nanofillers to PMMA at both 5% and 10% increased the microhardness, with values of up to 49.7 HV. The wear mechanism in the acrylic base material without nanoparticle addition was found to be fatigue wear; a high density of microcracks were found. The addition of 5 wt.% ZrO2 improved the wear resistance. Increasing the nanoparticles to 10 wt.% ZrO2 further improved the wear resistance, with no microcracks found.

Influence of Dimethacrylate Monomer on the Polymerization Efficacy of Resin-Based Dental Cements—FTIR Analysis

The degree of polymerization for dimethacrylate resin-based materials (BisGMA, TEGDMA, UDMA, HEMA) ranges from 55 to 75%. Literature data indicate that polymerization efficacy depends, among other factors, on the type of methacrylate resin comprising the material. The aim of this study was to evaluate the polymerization efficacy of four dental cement materials characterized by different polymerization mechanisms using FTIR analysis. In the present study, the FTIR method was adopted to analyze the degree of polymerization efficacy of four resin-based dental cement materials, two of which were self-cured and two were dual-cured cements. The IR spectral analysis was performed 24 h after the polymerization of the cementitious material. RelyX ARC cement exhibits the lowest polymerization efficacy (61.3%), while that of Variolink II (85.8%) and Maxcem Elite is the highest (90.1%). Although the efficacy of self-cured cements appears to be superior, the difference is not statistically significant (p = 0.280). Polymerization efficacy largely depends on the chemical structure of the material in terms of the presence of a particular methacrylate resin and less on the polymerization mechanism itself, i.e., whether it is a self-cured or dually cured dental cement. Thus, in clinical practice, cementitious materials with a higher proportion of TEGDMA compared with BisGMA are recommended.

Histological Procedures Carried out During Coconut Somatic Embryogenesis.

Histological methods allow to characterize the developmental changes that occur in plant tissues during in vitro culturing of explants. Different procedures to assess these changes have been reported in the literature. Here we describe a simple histological procedure to evaluate the development of explants using the fixation with paraformaldehyde, embedding with methacrylate resin and staining with periodic acid Schiff's reagent and naphthol blue black. This method allows to obtain high contrast in the stained cells, for a better characterization of cellular events that occur during coconut somatic embryogenesis.

3D printed contact lenses for the management of color blindness

Color blindness or color vision deficiency (CVD), a congenital ocular disorder, affects one in 12 males and one in 200 females. CVD currently has no cure; hence, patients opt for wearables that could enhance their color perception such as color filtering glasses and lenses. Herein, we report 3D printing of contact lenses for color blindness management. We utilized an in situ synthesized poly(2-hydroxyethyl methacrylate) (pHEMA) resin and wavelength selective filtering dyes. 3D printing has advantages as compared to conventional techniques due to its ease of manufacturing and high dimensional accuracy, making it a suitable platform for the fabrication of customized contact lenses for colorblindness. Moreover, to filter out the undesired wavelengths, two dyes (i.e., Atto 565 and 488) were utilized to functionalize in the contact lenses. These dyes have absorption bands in the range of 550–580 and 480–500 nm wavelength. The tinted contact lenses successfully blocked 80–90% of the undesired wavelengths, where CVD patients find difficulties in distinguishing shades of certain colors. Furthermore, no dye leakage was observed from the 3D printed hydrogel contact lenses. The fabricated contact lenses were further characterized by optical and physicochemical methods. Contact lenses were tested on colorblind patients using Ishihara test, and evident enhancements in the color perception of the participants were obtained.

Effectiveness of using organic and inorganic consolidants on the properties of friable-porous gypsum mortar

This paper essentially deals with the influence of various consolidation materials on the mechanical and micro-structural behaviour of feeble Gypsum mortar. Gypsum mortars suffer from a serious drawback of high porous nature due to the lack of proper binding property of gypsum plaster with siliceous fine aggregate. The consolidation products chosen in this study were lime water, Barium water, ammonium oxalate, polymethyl methacrylate and epoxy resin. The results obtained from these consolidation treatments were compared to that of a commercial silane-based product available in the market. From the results, it was clear that the consolidation products proved to be very effective both in terms of mechanical and water resistance property, thereby increasing the cohesion and improved the internal stability of the gypsum mortar. The cognitive results obtained were significant in choosing the best treatment for Gypsum mortar, which can be a promising technique for the renovation of historic buildings and in future artistic constructions.

On photostability of acrylate and polymethyl methacrylate planar fiber-like structures with CUMARIN 7, 47, 120; POPOP; NOL8 luminophores for UV information systems

Studies of photostability of planar fiber-like structures in the form of films 600-800 μm thick made of high-purity polymethyl methacrylate (PMMA) and acrylic resin, in which CUMARIN 7, 47, 120; POPOP, NOL8 luminophores were introduced, were carried out under long-term ultraviolet (UV) irradiation. NOL12 (KNL12) luminophore was in polymer fibers produced by "Engineering Centre for Polymer Optical Fibers" LLC. PMMA fiber-optic guides were attached to the ends of the films, from the output of these guides the luminescence radiation power was measured as a function of the UV irradiation power and time. The prospects of applying Cumarin-type luminophores for using planar fiber-like structures in UV information systems as receiving antennas for optical telecommunications and optical sensors for monitoring physical fields are shown. Keywords: photostability, planar fiber-like structures, luminophores, information systems.

Retraction: Non-thermal microwave effects in radical polymerization of bio-based terpenoid (meth)acrylates

Retraction of ‘Non-thermal microwave effects in radical polymerization of bio-based terpenoid (meth)acrylates’ by Thibault Castagnet, et al., Polym. Chem., 2020, 11, 6840–6846, DOI: 10.1039/D0PY01192D.

Effect of Weathering on Some Mechanical Properties of Prosthetic Composites

In this research, the concerted influence of ultraviolet (UV) light and water spurting on the mechanical characteristics of the naturally strengthened composites was explored. Specimens fabricated by the vacuum bagging procedure were subjected to an accelerated weathering device for 100 h. Tensile, flexural; compression tests were executed to assess the mechanical characteristics. The laminates encompass woven synthetic and natural fabric. The results exhibited that consuming altered forms of reinforcing materials had an abundant influence on the properties and the values of (tensile, flexural, and compressive characteristics) reduced under the collective influence of UV and water spurting cycles. The results advocate that the arrangement of natural and synthetic reinforcements permits the preparation of biocomposites with improved performance. This work revealed the assets of natural hybrid reinforced Polymethyl methacrylate resin composites (hybridized at various volume percentages and lamination layup), which have not been tried up to now.

Polymethyl methacrylate resin for provisional restoration affects rat macrophage function in in vitro conditions.

This study evaluated the cytotoxic effects of polymethyl methacrylate resin extracts on rat macrophage viability in in vitro conditions. Prepared test specimens were immersed in 5 mL of artificial saliva and incubated for 24, 48, and 72 h at 37°C. The cytotoxicity of the obtained solutions of extracted resins, used as a stock solution (100%) and diluted with Roswell Park Memorial Institute (RPMI) medium to obtain the working solutions (50, 40, 30, 20, 10, and 5%), was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. No dose-dependent toxic activity in macrophage culture was detected for the three types of extracts obtained after 24, 48, and 72 h of material extraction. The shortest extraction of material was found to be completely non-toxic, and the 20% concentration of this extract obtained caused a significant increase in cell ability to metabolize MTT. Extracts obtained after 72 h of extraction showed the highest cytotoxic potential of 50%, 40% and 30%, and extracts obtained after 48 and 72 h of extraction at concentrations of 5% and 10% had a proliferative effect on the macrophage cell line. This study demonstrated that the highest cytotoxic effect was observed in cells exposed to the highest concentrations (50, 40, and 30%) of the extracts that were extracted for 72 h.

Synthesis of Epoxy Methacrylate Resin and Coatings Preparation by Cationic and Radical Photocrosslinking.

This work involves the synthesis of hybrid oligomers based on the epoxy methacrylate resin. The EA resin was obtained by the modification of industrial-grade bisphenol A-based epoxy resin and methacrylic acid has been synthesized in order to develop multifunctional resins comprising both epoxide group and reactive, terminal unsaturation. Owing to the presence of both epoxy and double carbon–carbon pendant groups, the reaction product exhibits photocrosslinking via two distinct mechanisms: (i) cationic ring-opening polymerization and (ii) free radical polymerization. Monitoring of EA synthesis reactions over time using PAVs, MAAC and NV parameters, and the FT-IR method reveals that esterification reactions proceed faster at the start, exhibiting over 40% of conversion within the initial 60 min, which can be associated with a relatively high concentration of reactive sites and low viscosity of the reaction mixture at the initial reaction stage. With the further increase in the reaction time, the reaction rate tends to decrease. The control of the EA synthesis process can guide how to adjust reactions to obtain EAs with desired characteristics. Based on obtained values, one can state that the optimum synthesis time of about 4–5 h should be adopted to prepare EAs having both epoxy groups and unsaturated double bonds. The structure of the obtained EA was confirmed by FT-IR and NMR methods, as well as the determination of partial acid value and epoxy equivalent. Samples at various stages of synthesis were cured with UV radiation in order to study the kinetics of the process according to cationic and radical polymerization determined via photo-differential scanning calorimetry (photo-DSC) and real-time infrared spectroscopy (RT-IR) and then the properties of the cured coatings were tested. It turned out that the cationic polymerization was slower with a lower conversion of the photoreactive groups, as compared to the radical polymerization. All the obtained EA coatings were characterized by good properties of cured coatings and can be successfully used in the coating-forming sector.

Effects of Monomer Composition of Urethane Methacrylate Based Resins on the C=C Degree of Conversion, Residual Monomer Content and Mechanical Properties.

(1) Background: This study investigated the influence of Bis-GMA, TEGDMA, UDMA, and two different polyethylene glycol (PEG)-containing, UDMO-based co-monomers on the Young’s modulus and flexural strength, degree of methacrylate C=C double bond conversion and residual monomer elution of experimental dental resins. (2) Methods: Urethane methacrylate-based monomer was synthesised via a radical chain growth polymerization mechanism using PEG in order to improve the mechanical properties. Dental resins were formulated using Bis-GMA, UDMA, or UDMO as base monomers combined with TEGDMA as a dilution monomer and DMAEM + CQ as the photo-initiator system. Degree of conversion (DC), mechanical properties, and residual monomer content of light-activated methacrylate resin formulations were evaluated and statistically analysed by ANOVA and a Tukey’s test. (3) Results: PEG-containing UDMO resins had lower Young’s modulus and elastic strength than UDMA-derived resin for all irradiation times. The highest DC (67,418%) was observed for the PEG-containing UDMO-based resin formulation when light cured for 40 s. For all samples, DC increased with the photo-polymerization time. The amount of residual monomer decreased after increasing the light-curing period from 20 to 40 s, resin with UDMO content 0.01 mol of PEG having the smallest amount of free eluted monomer. (4) Conclusions: A strong structure–property relationship exists in photo-cured dimethacrylate-based dental resins. The time and quantity of the photochemical initiation system can influence the physical–mechanical properties of the resins but also the monomers in their composition.

Alternating bio‐based pyridinic copolymers modified with hydrophilic and hydrophobic spacers as sorbents of aromatic pollutants

AbstractThe main objective of this work was to design new advanced sorbent phases, alternating copolymers, derived from isosorbide and 2,6‐difluorpyridine, to be used for the removal of aromatic organic pollutants present in water at low concentrations. Six different monomers, dianhydrohexitols isomers and bisphenol derivatives, were synthesized in order to make it possible to study their hydrophilic and hydrophobic effect on the sorption efficiency of the resulting polymeric phases. Before this study, we have confirmed the chemicals structures, molecular weights, and thermal properties of the obtained polymeric phases. Sorption results show a higher adsorption efficiency of P6 co‐poly(ether‐pyridine) based on bisphenol substituted with pyridine units, for all tested pollutants, hydrophobic and hydrophilic ones, due to its less compact structure. Two aromatic organic pollutants, p‐hydroxybenzoic acid and toluic acid, were selected as sorbates to study the adsorption characteristic, kinetics and isotherms of the co‐poly(ether pyridine) P6. Langmuir model led to a better fitting of the sorption isotherms; the sorption of toluic acid is easier than of that p‐hydroxybenzoic acid. Comparing 1/n values for benzoic acid was two time lower for P6 compared to that for biochar and for cross‐linked methacrylate resin, showing a higher efficiency.

Preparation of poly hydroxamic acid from poly (styrene –methyl metha acrylate) and study of the kinetics of nickel ion sorption by the prepared acid

In this paper, the copolymer (styrene-methyl methacrylate) was prepared by using free radical polymerization for the copolymerization between methyl methacrylate and styrene in an equal molar mixing ratio and using benzoyl peroxide as a starter at a temperature of 70 °C. Then the prepared copolymer was converted to poly hydroxamic acid, and this was done by reacting the copolymer with hydroxylamine hydrochloride at a base medium of = 13 using sodium hydroxide with heat escalation for a period of 70 °C. The nickel ion sorption capacity of the resultant product was evaluated using poly hydroxamic acid and spectroscopic FT-IR. As well as studying the effect of time, temperature, and acidity function on the sorption capacity by chelating poly hydroxamic acid. Where it was shown that the capacity of adsorption increases with increasing time and decreases with increase in temperature mediated by poly hydroxamic acid. The equations of Arrhenius and Vant Hof were used, and from the enthalpy values, it was shown that the reaction was exothermic, and from the negative compression energy values, it was found that the reaction is spontaneous and the type of physical detention is mediated by poly hydroxamic acid.

Effect of Locator and Telescopic Attachment on Retention value for Two-Piece and One-Piece Implant-Supported Palateless Maxillary Over Denture: An In-vitro study

Objective: This study aims to evaluate the effect of two different implant designs (one-piece dental implant and two-piece dental implant) with attachment systems on retention value in implant-supported palate less maxillary overdenture. 
 Methods: Two edentulous maxillary models were fabricated from cold-cure polymethyl methacrylate resin. Four implants were inserted for each model as follows: Model I (Four one-piece implants were inserted, two implants in the canine region and two implants in the second premolar region), while Model II (Four two-piece implants were inserted, two implants in the canine region and two implants in second premolar region). The maxillary denture was constructed over each model. In model I, four ready-made titanium telescopic attachments corresponding to implant abutments were embedded in the inner surface of the overdenture. In contrast, in model II, four locator attachments corresponding to implant abutments were embedded in the inner surface of the overdenture. Initial anterior, posterior, and central retention values of overdentures were recorded and compared with the retention after 540 and 1080 cycles of insertion and removal using a digital force gauge. 
 Results: Statistical analysis revealed significant differences in the initial, secondary and tertiary retention values for anterior, posterior, and central retentions for both models (higher values were recorded before insertion cycles). The higher anterior and central retention values were recorded in Model II (44.93 and 25.9) N respectively, on the other hand, the higher posterior retention value was recorded for Model I 23.3N. 
 Conclusions: The type of attachment affects the retention value of maxillary overdenture. Continuous insertion and removal of the prosthesis lead to a decrease in the retention values.

Fusion of Glutamate Dehydrogenase and Formate Dehydrogenase Yields a Bifunctional Efficient Biocatalyst for the Continuous Removal of Ammonia

A novel fusion protein has been rationally designed, combining the hexameric glutamate dehydrogenase from Clostridium symbiosum with the dimeric formate dehydrogenase from Candida boidinii. The former enzyme consumes ammonia for the reductive amination of α-ketoglutarate using NADH, while the latter biocatalyst regenerates continuously the cofactor. This enzymes fusion opens new perspectives for the detection and the removal of ammonia. The bifunctional biocatalyst has been successfully created, expressed, and then characterized. The two fused protein domains retained identical properties and catalytic activity of the individual enzymes. Additionally, the immobilization on a methacrylate resin optimized the assembly providing a reusable and stable biocatalyst. This is an example of immobilization of a fusion protein, so that efficiency and sustainability of the process are enhanced. The immobilized biocatalyst could be recycled 10 times retaining still half of the initial activity. Such preparation outperforms the co-immobilized wild-type enzymes in the conversion of 300 mM of ammonia, which could be carried out also in continuous mode.