Introduction: The aesthetics of a dental prosthesis should blend with the surrounding soft tissues, particularly in the anterior region of the dentition. Advances in laboratory technology and dental materials have enabled us to produce aesthetically pleasing, customised dentures that closely resemble each patient’s intraoral features. Need for the study: Conventional denture fabrication lacks the natural appearance of healthy gingiva. When denture bases are fabricated with Polymethyl Methacrylate (PMMA) resin, aesthetics are restricted. Consequently, attempts have been made to fabricate cosmetic dentures tili using various intrinsic techniques (colour-matching resins) and more contemporary extrinsic techniques (gingival shade composite resin). Aim: The aim of this study is to use a colourimeter software application on a mobile phone to compare the colour stability of denture characterisation using two distinct methods (intrinsic and extrinsic). Materials and Methods: This experimental study will be conducted in the Department of Prosthodontics and Crown and Bridge at Sharad Pawar Dental College and Hospital, Sawangi (M), Wardha, Maharashtra, India, from July 2024 to January 2026. The study will involve two groups using two different characterisation methods: extrinsic (using gingival shade composite resin) and intrinsic (using colour blending resins). Colour stability will be assessed using a mobile phone colourimeter application based on Hue, Saturation, and Value (HSV), following pre- and poststaining with three solutions: tea, coffee, and turmeric solution. The normality of continuous outcome variables will be assessed initially at the 5% level of significance (p≤0.05) employing the Kolmogorov–Smirnov test. Significant differences between groups at the 5% level (p≤0.05) will be determined using an independent t-test.

Biosynthesized selenium nanoparticles enhance antibiofilm properties of PMMA resin for dental applications.

The development of dental restorative materials with improved physical and mechanical properties is an important area of research. In this study, hexaallylaminocyclotriphosphazene (HAP) was used to modify dental composites. HAP is a compound with multiple carbon-carbon bonds that can react with methacrylic resins to form a copolymer. HAP was synthesized by reacting allylamine with hexachlorocyclotriphosphazene and characterized it using 1H and 31P NMR spectroscopy and MALDI-TOF mass spectrometry. Molecular dynamics simulations using the MM2 force field showed that HAP has a nanosize (the diameter of a sphere eclosing the molecule is 1.3 nm), making it a suitable nanomodifier for dental composites. Using 3D printing, samples of dental methacrylic composites containing up to 10 wt. % HAP were prepared and their physicomechanical properties and antibacterial activity against gram-positive bacteria S. mutans were studied. As a result, it was established that the maximum flexural strength (115.1 ± 10.2 MPa) is achieved with a modifier content of 5 wt.% in the composite. The maximum value of inhibition of S. mutans growth in a liquid nutrient medium is achieved with a HAP content of 10 wt.% in the sample. Furthermore, with a HAP content of more than 5 wt.% in the composite, inhibition of biofilm on the material surface is observed. The resulting composite is proposed for use as dental crowns in restorative dentistry.

Rapidly photocrosslinkable charged silk-based hydrogel for emergency hemostasis and multifunctional wound therapy

This study investigates the performance of three commonly used waterproof bonding layer materials for steel bridge decks—solvent-based rubber asphalt, methyl methacrylate (MMA) resin, and epoxy resin—through surface energy theory, pull-off tests, and interlayer shear tests. The results indicate that MMA resin exhibits the highest surface energy parameters, followed by epoxy resin, while solvent-based rubber asphalt shows the lowest values. Pull-off tests reveal that epoxy resin achieves peak bond strength (10.22 MPa) after 60 h of curing at 25 °C, whereas solvent-based rubber asphalt performs best at an application rate of 0.4 kg/m2. Interlayer shear tests demonstrate that epoxy resin provides the highest shear strength, which increases with loading rate but decreases significantly at elevated temperatures. Additionally, temperature significantly affects bonding performance, with epoxy and MMA resins outperforming solvent-based rubber asphalt under high-temperature conditions. This research provides a theoretical basis for material selection and construction parameter optimization of waterproof bonding layers for steel bridge decks.

Background: Fiber-reinforced composite (FRC) fixed partial dentures (FPDs) offer a cost-effective, minimally invasive, and less technique-sensitive alternative for replacing missing teeth. Among the commonly used designs, box-shaped and tub-shaped tooth preparations are frequently applied to restore posterior teeth. Identifying the more effective design can enhance the clinical success of FRC FPDs. Objective: This study aimed to compare the fracture strength and bending behavior of box-shaped and tub-shaped tooth preparations in FRC FPDs replacing a first molar. Materials and Methods: This in vitro experimental comparative study was conducted in the Department of Prosthodontics, BMU, over six months. Extracted premolar and molar teeth were mounted in polymethyl methacrylate resin blocks with an 11 mm edentulous span to simulate clinical conditions. Eighteen specimens were divided equally into two groups: box-shaped and tub-shaped preparations. After tooth preparation, impressions were taken, casts poured, and FRC FPDs fabricated and cemented. All specimens were stored in distilled water for 24 hours before testing. Fracture strength and bending amounts were measured using a universal testing machine, and fracture sites were evaluated radiographically. Results: The box-shaped preparation demonstrated significantly higher fracture strength (509.67 ± 24.02 N) than the tub-shaped preparation (449.56 ± 46.09 N) (p = 0.003). Bending amounts were also greater in the box-shaped group (1.24 ± 0.20 mm) than in the tub-shaped group (0.87 ± 0.25 mm) (p = 0.003). Most fractures occurred in the veneering material with no significant difference between groups (p > 0.99). Conclusion: Box-shaped tooth preparation provides superior strength and flexibility and may be preferred for FRC FPDs replacing first molars.

Despite the widespread use of photopolymerizable methacrylate resins in additive manufacturing, their potential for creating functional biomedical materials remains untapped. Standard resins, while possessing good technological properties, are typically biologically inert and unable to combat such a critical problem as bacterial colonization. In this work, we propose incorporating selenium nanoparticles (Se NPs) into a photopolymerizable resin based on methacrylate monomers to obtain functional composite materials in the MSLA printing process. Composite material samples made from modified resins showed no structural surface defects and were characterized by a non-uniform distribution of NPs in volume and demonstrated a higher degree of monomer conversion. The materials demonstrated significant antioxidant activity, removing OH-radicals and H2O2 and reducing the level of biomarkers of oxidative damage (8-oxoguanine in DNA and long-lived reactive protein species). A dose-dependent bacteriostatic effect was observed in E. coli cell cultures against a background of high cytocompatibility with human cell cultures. The developed photopolymerizable resins modified with Se NPs allow obtaining products that combine the properties of a bacteriostatic agent with antioxidant properties and high biocompatibility, which is of considerable interest in terms of materials for biomedical applications.

Reliable waterproofing protection is one of the conditions for ensuring the durability of transport and hydraulic structures. However, among the dominant causes of the destruction of transport and hydraulic structures is the premature destruction of waterproofing, which is one of the least durable elements of the span structure. A waterproofing system used to protect concrete and metal structures of transport and hydraulic construction must have reliability, which is represented by the performance of the necessary functions under operating conditions for a given time while maintaining the main characteristics, and have a service life as close as possible to the structures being insulated. Waterproofing materials have two interrelated characteristics: internal structure and quality indicators. The relationship is established with optimal structures, when stable bonds in them ensure the stability of the main properties during various external and internal changes in the material in the structures. The internal structure, or structure, of waterproofing materials expresses a certain nature of the bonds and the order of adhesion of the particles from which they are formed. The most advanced in terms of ensuring the protection of the slab are liquid composite membranes based on polyurethane and methyl methacrylate resins. Membrane coatings form a continuous seamless structure on surfaces of complex shape, since their application is carried out by the method of liquid spraying. Research into the influence of various factors on the durability of waterproofing membranes based on methyl methacrylate is a crucial component for developing a technology for installing waterproofing membranes based on methyl methacrylate resin on transport and hydraulic structures and establishing requirements for them. Problems. It has been established that there is a need to generalize existing approaches to protecting concrete and metal structures in transport and hydraulic engineering construction and to develop recommendations for the installation of waterproofing systems based on methyl methacrylate resin. Objectives. The purpose of the scientific work is to conduct research aimed at generalizing the protection of concrete and metal structures of transport and hydraulic engineering using methyl methacrylates, which are arranged in the form of waterproofing of structures.

To evaluate the flexural and impact strength of heat- cured polymethyl methacrylate and vertex resins after disinfection with alkaline peroxide and sodium hypochlorite solution. The in-vitro, experimental study was conducted at the Dr Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Karachi, from June 15, 2019, to May 31, 2020, and comprised samples of polymethyl methacrylate and vertex rapid simplified resins that were fabricated using custom metal moulds. The samples were divided into three groups based on the immersion medium: distilled water (control group), alkaline peroxide, and sodium hypochlorite. An immersion time of 6 hours was chosen to simulate one day, thereby three months of continuous immersion represented one year. The samples were then subjected to a 3-point bending test and the Pendulum Impact test to evaluate their flexural and impact strength, respectively. Data was analysed using SPSS 21. There were 90 samples each of polymethyl methacrylate and vertex rapid simplified resins. There was a significant difference in the mean values of impact strength between polymethyl methacrylate and vertex rapid simplified resins following immersion in the disinfectants (p<0.05). However, no significant difference was observed in flexural strength among the groups subjected to immersions in alkaline peroxide and sodium hypochlorite solutions (p>0.05). The immersion in denture cleansers led to an enhancement in both flexural and impact strength for vertex resin simplified resins compared to conventional polymethyl methacrylate denture base materials.

Abstract This work investigates the feasibility of recovering and regenerating uncured methacrylate-based photocurable resin from a previous 3D printing build job before being reused for a consecutive second and third build job. In detail, it was investigated the impact of the uncured resin reuse on the optical performance of 3D-printed micro-optofluidic (MoF) devices designed for absorption-based optical slug flow monitoring by comparing their optical performances when manufactured with fresh or one-time or two-times reused resin. The devices were fabricated using Projection Micro-Stereolithography with three different resin batches: fresh, one-time or two-times reused resin. Optical performance testing was conducted using an air–water slug flow. A Design of Experiment approach was employed to systematically evaluate the MoF device optical performance variability due to resin reuse. Despite Fourier Transform Infrared Attenuated Total Reflection spectroscopy has revealed minor chemical reduction in the methacrylate monomers composition of reused resins when compared to fresh one, a negligible reproducibility error in terms of optical detection performance for the MoF devices manufactured with different batches of resin was unveiled. This is attributable to stable resin cross-linking, ensuring a uniform refractive index and reliable optical sensing performance. The recovery, regeneration, and reuse of photocurable resin provide a sustainable solution to recycling challenges posed by utilization of uncured acrylate and methacrylate resins, as material waste in manufacturing can be reduced without compromising optical performance, thus promoting environmental sustainability. The presented sustainable approach allows to reduce costs, since the high cost of photopolymer resins limits large-scale manufacturing, besides minimizing environmental impact. Graphical Abstract

This study employed a green route to synthesize metal oxide nanocomposites, specifically NiO/Al2O3, which were subsequently used to dope poly(methyl methacrylate) (PMMA) as a matrix, resulting in the formation of novel nanocomposites, namely PMMA/NiO/Al2O3. The nanocomposites were characterized using FE-SEM, XRD, DSC, TGA, antioxidant activity, and antibacterial activity tests to confirm their design, verify the nanostructured composition, and distinguishable features in poly methyl methacrylate distribution. The results of AFM for the synthesized nanostructured showed that the NiO and Al2O3, describe how the nanoparticles' size was in the nano scale. The biological activities of nanocomposites synthesized were studied, including antioxidant and the use of these nanocomposites as inhibitors for bactria also as anticancer. The findings for all of these nanocomposites revealed they have the properties of a significant inhibitory effect.

The aim of this study was to evaluate the efficacy of antimicrobial photodynamic therapy (aPDT) using toluidine blue (TBO) activated by a diode laser and zinc oxide (ZnO) activated by light-emitting diode (LED) light in reducing bacterial accumulation on polymethyl methacrylate (PMMA) orthodontic appliances. This in-vitro study investigated the formation of Streptococcus mutans biofilm on 32 PMMA resin discs, divided into four groups. The first group consisted of acrylic discs containing ZnO exposed to 450nm LED radiation; the second group included acrylic discs with TBO and 635nm diode laser radiation; the third group was the positive control with chlorhexidine (CHX); and the fourth group served as the negative control. To evaluate biofilm formation, the discs were immersed in tubes containing a microbial suspension at a 0.5 McFarland concentration. Following incubation, the discs were exposed to light according to the type of photosensitizer. After washing with saline and sonication, bacterial colony counts were determined by serial dilution and culture in Brian Heart Infusion agar medium. One-way ANOVA was used to compare the colony-forming unit (CFU) counts, and post-hoc Tamhane's test was performed for pairwise comparisons, with statistical significance set at p < 0.05. The negative control group exhibited the highest mean colony count (35.72 ± 3.35 CFU/mL), while the positive control group showed the lowest mean colony count (5.87 ± 0.92 CFU/mL). Both ZnO and TBO groups, when activated by their respective light sources, demonstrated significant antibacterial activity compared to the negative control (P < 0.001 for both). However, CHX outperformed both ZnO and TBO in reducing bacterial growth (P < 0.001 and P = 0.007, respectively). No statistically significant difference was observed between the antibacterial effects of ZnO and TBO (P = 0.280). This study suggests that aPDT using ZnO and TBO can be an effective adjunctive treatment for reducing bacterial accumulation on orthodontic appliances. While CHX remains the most effective treatment, the cost-effectiveness and ease of application of both CHX and ZnO make them viable options for future clinical trials. Further research is needed to optimize treatment protocols and explore the potential impact of these treatments on other microorganisms and material properties.

Introducing multiple functionalities to contact lenses (CLs) are achieved by additives such as nanomaterials, pigments, and dyes. CLs with graphene have been used in electromagnetic interference (EMI) shielding, drug delivery and sensing. Generally, CVD graphene or graphene nanocomposites are used during the manufacturing stage of CLs. In this work, we incorporate graphene into commercial CLs through three post processing techniques: the breath in - breath out (BIBO) technique, immersion of CLs in graphene ink, and 3D printing of graphene hydrogel composite. Graphene ink was used as the aqueous solution in BIBO cycles. The BIBO cycles were repeated to obtain the necessary attachment without losing transparency. In the immersion technique, immersion time controlled the concentration of graphene. In the third method, graphene ink was dispersed in hydroxyethyl methacrylate (HEMA) resin to 3D print patterns onto the CLs. Scanning Electron Microscopy (SEM) was used to observe graphene dispersion within CLs. The UV-Vis spectroscopy of the CLs indicated steady absorption throughout the visible region as a tinting additive, suggesting uses such as broad-spectrum absorbers. These methods could be used to quickly synthesize large amount of functionalized CLs for different applications. The lenses exhibited both anti-bacterial and exceptional biocompatibility properties.

The main objective of this article is to review previous contributions on the applications of fluidized bed reactors (FBR) in biocatalysis. FBR combines the properties of a stirred tank reactor and a continuous tubular reactor, making it an efficient system for carrying out enzymatic reactions with immobilized enzymes. This equipment's advantages include its high transfer capacity and versatility, as it can be used with liquid and gaseous phases. According to the literature, these devices have been primarily used to degrade contaminants, synthesize cosmetic ingredients, produce food and pharmaceutical compounds, and synthesize biolubricants and biodiesel. The enzymes most used in fluidized bed mode are laccases, lipases, and proteases immobilized on methacrylate resins, mesoporous silicas, alginate, and chitosan beads. Enzyme immobilization is essential, as it can promote the suspension of biocatalyst particles, thereby increasing yields and productivity. One of the leading prospects for these systems is to stabilize the fluidized bed using a magnetic field and the concept of "microfluidization," which enables the stabilization of smaller biocatalyst particles with smaller equipment, thereby increasing efficiency and intensifying the biocatalytic process. In the future, the versatility of FBR will constitute an attractive alternative for developing biocatalytic systems.

This study investigated the influence of curing temperature and time on both the mechanical properties and cytotoxicity of stereolithographic polymethyl methacrylate (PMMA) resin. After printing using stereolithographic equipment, the resin was cured at 45 °C, 60 °C, and 75 °C for up to 120 min. Our results reveal that the mechanical properties achieved a peak after approximately 30 min of curing at the two highest temperatures, followed by a subsequent decrease, while curing at 45 °C resulted in a constant increase in mechanical properties up to 120 min. Testing with S. epidermidis and E. coli exhibited a bland antibacterial effect, with the number of living bacteria increasing with both the time and temperature of curing. To assess potential cytotoxicity, the materials were also tested with human fibroblasts, and the trends observed were similar to what was previously seen for both bacteria strains. Interestingly, an association was observed between the intensity ratio of two Raman bands (around 2920 and 2945 cm-1), indicative of long-PMMA-chain formation and cytotoxicity. This finding suggests that Raman spectroscopy has the potential to serve as a viable method for estimating the cytotoxicity of 3D printed PMMA objects.

Abstract High‐performance adhesives play a vital role in both daily life and numerous industrial sectors. Nevertheless, the adhesives currently available on the market generally face several challenges, including insufficient environmental friendliness, limitations in curing conditions, and an imbalance between cost and performance. Herein, a novel and versatile UV curing strategy is developed for the fabrication of dual‐network cellulose adhesives via copper coordination. Strong and tough bio‐based adhesives are prepared by modulating cellulose/adhesive interactions through the compatibility of the natural material of microcrystalline cellulose and copper chloride in methacrylic resin adhesives. The results indicate that the crosslinked network formed by the adhesive passes through the cellulose to the methacrylate resin, further balancing the cohesion and adhesion of the material is achieved with the addition of copper chloride. Notably, the resultant cellulose‐based adhesive displays high strength (32.6 MPa), outstanding shear strength (15.2 MPa), and excellent work of debonding (11 623 N m−1), while providing excellent tensile, solvent adaptability, long‐term usability, and closed‐loop recycling performance. This work demonstrates the feasibility of cellulose as a reinforcing agent for conventional adhesives and offers fresh perspectives for exploring bio‐adhesives.

Abstract Metal particle-reinforced polymer resin scaffolds are becoming increasingly prominent in biomedical applications due to their potential to support tissue regeneration and healing. These scaffolds are designed to serve as temporary frameworks that support affected tissues and gradually degrade during healing. The primary focus of these research efforts has been on determining the optimal materials and methods for creating these scaffolds, ensuring that they are biocompatible, capable of withstanding structural strains, and can support cellular proliferation, tissue growth, and vascularization. Despite the growing interest in polymers and their metal composites, a notable gap exists in leveraging the benefits of fabricating these composites through additive manufacturing techniques, particularly stereolithography (SLA). Magnesium (Mg), in particular, is a biocompatible and osteoconductive material known for its remarkable mechanical properties and biodegradability, making it highly suitable for bone implants. Additionally, Mg can potentially regenerate skin tissues and inhibit bacterial infections. Mg ions are crucial for wound healing because they repair the skin barrier and facilitate blood coagulation. This research focuses on finding optimal conditions for manufacturing magnesium-induced poly(methyl methacrylate) (PMMA) resin scaffolds using SLA. To evaluate their printability and the effect of different material compositions on the 3D-printed structures, PMMA resin was mixed with high-weight percentages (wt%) of Mg alloy WE43. This mixture was then used to 3D-print test coupons and scaffolds via SLA. The impact of Mg incorporation on the scaffold’s structural integrity, thermal degradation, and biological response was assessed through physicochemical and thermal characterization and biocompatibility experiments. Notably, pure PMMA exhibited the highest tensile strength, 26.23 ± 0.14 MPa and an elastic modulus of 707.81 MPa, while PMMA resin/1% Mg showed the lowest strength (19.46 ± 0.25 MPa) and modulus (392.88 MPa), indicating a decrease in mechanical integrity with higher Mg content. However, the thermal stability was enhanced with the addition of Mg as the thermal degradation onset improved from ∼310 to 335°C. The challenges encountered in manufacturing PMMA resin/Mg composites and their potential applications were discussed, highlighting the future directions and promising avenues for further research and development.

ABSTRACTIn situ polymerized poly(methyl methacrylate) resin, a liquid molding thermoplastic, offers advantages such as low cost, recyclability, and environmental friendliness. However, its poor toughness limits its application potential. This study proposes a toughening method for poly(methyl methacrylate) resin used in liquid molding by copolymerizing it with butyl acrylate (BA) and butyl methacrylate (BMA) monomers. The effects of BA or BMA on the polymerization reaction and mechanical properties were investigated, with a focus on improving toughness. Dynamic thermal analysis (DSC) and 13C NMR spectroscopy confirmed the formation of copolymers and the incorporation of BA or BMA monomers. The introduction of BA or BMA lowered the glass transition temperature but had minimal impact on the polymerization rate, with only a slight increase in polymerization time (14.77‰ and 4.320‰ for 8% BA or BMA, respectively). Adding small amounts of BA or BMA significantly enhanced the toughness of the resin. When the content reached 4%, elongation at break increased by 103% and 139%, and impact strength improved by 222% and 328%. These results shift the failure mode from brittle to ductile fracture, paving the way for the industrial application of high‐performance in situ polymerized poly(methyl methacrylate) resin.

ABSTRACT This research focused on enhancing the structural performance of untreated wood for potential structural applications through polymer infiltration. Three infiltration substances - methyl methacrylate resin (TT_a, TT_b), stabilizing resin (S17) and gelatine (Ga_M), and a control group of untreated raw wood were tested. The process combined in-situ polymerization with vacuum stabilization at −95 kPa, allowing deep polymer penetration. TT_B achieved the highest penetration by weight (Pw ≈ 63%). Mechanical characterization included compressive strength, stiffness, relative water absorption, density changes, biodegradability, and scanning electron microscopy (SEM) analysis. Due to high preparation effort, small specimens’ sizes (n = 4–8) were used, with T-tests for statistical evaluation. Infiltration with TT_b increased the compressive strength of wood parallel to the grain by 33% (p = 0.029) and the stiffness by 21% (p = 0.047). Perpendicular to the grain, stiffness rose 2.8-fold (p = 0.082), and ductility improved 1.5-fold (p = 0.001) compared to raw wood. SEM confirmed polymer deposition in the lumen structure. These findings demonstrate the potential of vacuum polymer infiltration, to enhance untreated wood’s mechanical properties. Further research is needed to refine polymer formulations, test long-term durability, and evaluate the environmental and economic feasibility of implementing this technology on a larger scale.

Background/Objectives: Autopolymerizing poly (methyl methacrylate) (PMMA) resin is widely used in provisional restorations; however, its inadequate mechanical properties represent a significant limitation. This study aimed to develop electrospun fibers with chemically reduced graphene oxide (rGO) and to evaluate the effect of fiber reinforcement on the mechanical and physical properties of a commercially available PMMA resin. Methods: Electrospinning was employed to produce nanofibers containing 0.02 wt% and 0.05 wt% rGO within a PMMA matrix. Fiber characterization was performed using SEM-EDS, XRD, TGA/DTG, and FTIR. Following characterization, the fibers were blended into PMMA resin at 1%, 2.5%, and 5% (by weight). The resulting fiber-reinforced composites were tested for flexural strength, elastic modulus, surface roughness, and Vickers microhardness. Results: The addition of 1% and 2.5% PMMA/rGO-0.02 fibers and 1% PMMA/rGO-0.05 fibers significantly improved the flexural strength of PMMA compared with the control group (p &lt; 0.05). A statistically significant increase in elastic modulus was observed only in the group containing 1% PMMA/rGO-0.02 fibers (p &lt; 0.05). However, there were no significant differences in surface roughness or microhardness between the control and experimental groups (p &gt; 0.05). Conclusions: Incorporating electrospun PMMA-rGO fibers into PMMA resin enhances flexural properties at low concentrations without altering surface characteristics. These findings suggest that such fiber-reinforced systems hold promises for improving the mechanical performance and functional longevity of provisional dental restorations under clinical conditions.