PMMA-Based Nanocomposites for Odontology Applications: A State-of-the-Art

Biocompatibility of mussel-inspired water-soluble tissue adhesives

Wound closure in surgeries is traditionally achieved using invasive methods such as sutures and staples. Adhesion-based wound closure methods such as tissue adhesives, sealants, and hemostats are slowly replacing these methods due to their ease of application. Although several chemistries have been developed and used commercially for wound closure, there is still a need for better tissue adhesives from the point of view of toxicity, wet-adhesion strength, and long-term bonding. Catechol chemistry has shown great promise in developing wet-set adhesives that meet these criteria. Herein, we have studied the biocompatibility of a catechol-based copolymer adhesive, poly([dopamine methacrylamide]-co-[methyl methacrylate]-co-[poly(ethylene glycol) methyl ether methacrylate]) or poly(catechol-MMA-OEG), which is soluble in water. The adhesive was injected subcutaneously in a mouse model on its own and in combination with a sodium periodate crosslinker. After 72 h, 4 weeks, and 12 weeks, the mice were euthanized and subjected to histopathological analysis. Both adhesives were present and still palpable at the end of 12 weeks. The moderate inflammation observed for the poly(catechol-MMA-OEG) cohort at 72 h had reduced to mild inflammation at the end of 12 weeks. However, the moderate inflammatory response observed for the poly(catechol-MMA-OEG) + crosslinker cohort at 72 h had not subsided at 12 weeks.

In silico assessment of biocompatibility and toxicity: molecular docking and dynamics simulation of PMMA-based dental materials for interim prosthetic restorations

AIM

This study aimed to comprehensively assess the biocompatibility and toxicity profiles of poly(methyl methacrylate) (PMMA) and its monomeric unit, methyl methacrylate (MMA), crucial components in dental materials for interim prosthetic restorations.

METHODOLOGY

Molecular docking was employed to predict the binding affinities, energetics, and steric features of MMA and PMMA with selected receptors involved in bone metabolism and tissue development, including RANKL, Fibronectin, BMP9, NOTCH2, and other related receptors. The HADDOCK standalone version was utilized for docking calculations, employing a Lamarckian genetic algorithm to explore the conformational space of ligand-receptor interactions. Furthermore, molecular dynamics (MD) simulations over 100 nanoseconds were conducted using the GROMACS package to evaluate dynamic actions and structural stability. The LigandScout was utilized for pharmacophore modeling, which employs a shape-based screening approach to identify potential ligand binding sites on protein targets.

RESULTS

The molecular docking studies elucidated promising interactions between PMMA and MMA with key biomolecular targets relevant to dental applications. MD simulation results provided strong evidence supporting the structural stability of PMMA complexes over time. Pharmacophore modeling highlighted the significance of carbonyl and hydroxyl groups as pharmacophoric features, indicating compounds with favorable biocompatibility profiles.

CONCLUSION

This study underscores the potential of PMMA in dental applications, emphasizing its structural stability, molecular interactions, and safety considerations. These findings lay a foundation for future advancements in dental biomaterials, guiding the design and optimization of materials for enhanced biocompatibility. Future directions include experimental validation of computational findings and the development of PMMA-based dental materials with improved biocompatibility and clinical performance.

Incorporating versus coating antimicrobials for polymethyl methacrylate: A systematic review

STATEMENT OF PROBLEM

Incorporating and coating with antimicrobials are techniques that can confer antimicrobial action on polymethyl methacrylate (PMMA) denture bases, which can accumulate microorganisms and promote oral and systemic disease.

PURPOSE

The purpose of this systematic review was to answer the question: "Do techniques for incorporating and coating antimicrobial agents in PMMA promote antimicrobial action?"

MATERIAL AND METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist guidelines were followed, and the SCOPUS, PubMed/Medline, EMBASE, and Science Direct databases searched. The studies were selected in 2 stages, reading the titles and abstracts and then reading the selected studies in full. The risk of bias was analyzed by adapting the quasi-experimental studies tool by the Joanna Briggs Institute (JBI).

RESULTS

A total of 970 articles were found in the databases; 71 were duplicates and, after reading the abstracts, 38 were selected for full reading. From these, 6 were excluded because they did not fulfill the inclusion criteria, and 32 studies were included in this review. Autopolymerizing, heat- polymerizing, and light-polymerizing resins were evaluated, with the incorporating technique prevailing over the coating, but both techniques effectively promoted antimicrobial activity.

CONCLUSIONS

Incorporating and coating antimicrobial agents are effective methods of promoting antimicrobial activity in PMMA. Combining the 2 methods led to increased antimicrobial activity compared with each individually.

Composite Nanomaterials Based on Polymethylmethacrylate Doped with Carbon Nanotubes and Nanoparticles: A Review

Composite polymer materials have high strength and lightness, which makes them attractive for use in a variety of structures and products. The present article contains an overview of modern works devoted to the production of composite materials based on poly(methyl methacrylate) (PMMA) with improved characteristics. The possibility of obtaining such materials can be a key area for creating more efficient and durable products in various industries. Various methods were considered to improve the characteristics of PMMA by doping the polymer matrix with carbon nanotubes (CNTs), graphite, nanohydroxyapatite particles, micro-zirconia nanoparticles, titanium dioxide, etc. The possibilities of using the obtained composite materials in various industries such as aviation, automotive, construction, medical and others are discussed. This article also presents the results of our own research on the mechanisms of interaction of PMMA with single-layer CNTs, leading to the creation of a composite polymer system "PMMA+CNT", achieved using the modern quantum chemical method DFT. This article presents a review of the recent research on the effect of CNTs on the mechanical and electrically conductive properties of nanocomposite materials. The outcomes of this study can be important for the development of science and technology in various fields, from fundamental chemistry to applied scientific research.

NIR-responsive magnesium phosphate cement loaded with simvastatin-nanoparticles with biocompatibility and osteogenesis ability

The insufficient osteogenesis of magnesium phosphate cement (MPC) limits its biomedical application. It is of great significance to develop a bioactive MPC with osteogenic performance. In this study, an injectable MPC was reinforced by the incorporation of a near infrared (NIR)-responsive nanocontainer, which was based on simvastatin (SIM)-loaded mesoporous silica nanoparticles (MSNs) modified with a polydopamine (PDA) bilayer, named SMP. In addition, chitosan (CHI) was introduced into MPC (K-struvite) to enhance its mechanical properties and cytocompatibility. The results showed that nanocontainer-incorporated MPC possessed a prolonged setting time, almost neutral pH, excellent injectability, and enhanced compressive strength. Immersion tests indicated that SMP-CHI MPC could suppress rapid degradation. Based on its physicochemical features, the SMP-CHI MPC had good biocompatibility and osteogenesis properties, as shown via in vitro and in vivo experiments. These findings can provide a simple way to produce a multifunctional MPC with improved osteogenesis for further orthopedic applications.

Fibromodulin facilitates the osteogenic effect of Masquelet's induced membrane by inhibiting the TGF-β/SMAD signaling pathway

Masquelet's induced membrane (IM) technique is a promising treatment strategy for the repair of substantial bone defects. The formation of an IM around polymethylmethacrylate bone cement plays a crucial role in this technique. Several studies have indicated that IMs have bioactivity because they contain abundant blood vessels, a variety of cells, and biological factors. The bioactivity of an IM increases during the initial stages of formation, thereby facilitating bone regeneration and remodeling. Nevertheless, the precise mechanisms underlying the enhancement of IM bioactivity and the promotion of bone regeneration necessitate further investigation. In this study, we successfully developed a Masquelet IM model of critical femur defects in rats. By employing proteomics analysis and biological detection techniques, we identified fibromodulin (FMOD) as a pivotal factor contributing to angiogenesis and the enhanced bioactivity of the IM. A significant increase in angiogenesis and the expression of bioactive factors in the IM was also observed with the upregulation of FMOD expression. Furthermore, this effect is mediated through the inhibition of the transforming growth factor beta (TGF-β)/SMAD signaling pathway. We also demonstrated that administering recombinant human FMOD enhanced osteogenesis in rat bone marrow mesenchymal stem cells and angiogenesis in human umbilical vein endothelial cells in vitro. Furthermore, the negative regulatory effect of the TGF-β signaling pathway was verified. In conclusion, this study provides a novel theoretical basis for the application of IMs in bone-defect reconstruction and explores possible new mechanisms that may play an important role in promoting the bioactivity and osteogenic potential of IMs.

NIR-responsive injectable magnesium phosphate bone cement loaded with icariin promotes osteogenesis

There were defects like limited osteogenesis and fast drug release in traditional magnesium phosphate bone cement (MPC). In this study, we loaded icariin in a mesoporous nano silica container modified by polydopamine and then added it and citric acid into MPC (IHP-CA MPCs). The results indicate that IHP-CA MPCs have a long curing time, almost neutral pH value, excellent injectability, and compressive strength. In vitro experiments have shown that IHP-CA MPCs have good biocompatibility and bone promoting ability. These improvements provide feasible solutions and references for the clinical application of MPCs as implants.

Poly(methyl methacrylate) in Orthopedics: Strategies, Challenges, and Prospects in Bone Tissue Engineering

Poly(methyl methacrylate) (PMMA) is widely used in orthopedic applications, including bone cement in total joint replacement surgery, bone fillers, and bone substitutes due to its affordability, biocompatibility, and processability. However, the bone regeneration efficiency of PMMA is limited because of its lack of bioactivity, poor osseointegration, and non-degradability. The use of bone cement also has disadvantages such as methyl methacrylate (MMA) release and high exothermic temperature during the polymerization of PMMA, which can cause thermal necrosis. To address these problems, various strategies have been adopted, such as surface modification techniques and the incorporation of various bioactive agents and biopolymers into PMMA. In this review, the physicochemical properties and synthesis methods of PMMA are discussed, with a special focus on the utilization of various PMMA composites in bone tissue engineering. Additionally, the challenges involved in incorporating PMMA into regenerative medicine are discussed with suitable research findings with the intention of providing insightful advice to support its successful clinical applications.

Influence of Novel SrTiO3/MnO2 Hybrid Nanoparticles on Poly(methyl methacrylate) Thermal and Mechanical Behavior

While dental poly methyl methacrylate(PMMA) possesses distinctive qualities such as ease of fabrication, cost-effectiveness, and favorable physical and mechanical properties, these attributes alone are inadequate to impart the necessary impact strength and hardness. Consequently, pure PMMA is less suitable for dental applications. This research focused on the incorporation of Strontium titanate (SrTiO3-STO) and hybrid filler STO/Manganese oxide (MnO2) to improve impact resistance and hardness. The potential of STO in reinforcing PMMA is poorly investigated, while hybrid filler STO/MnO2 has not been presented yet. Differential scanning calorimetry is conducted in order to investigate the agglomeration influence on the PMMA glass transition temperature (Tg), as well as the leaching of residual monomer and volatile additives that could pose a threat to human health. It has been determined that agglomeration with 1 wt% loading had no influence on Tg, while the first scan revealed differences in evaporation of small molecules, in favor of composite PMMA-STO/MnO2, which showed the trapping potential of volatiles. Investigations of mechanical properties have revealed the significant influence of hybrid STO/MnO2 filler on microhardness and total absorbed impact energy, which were increased by 89.9% and 145.4%, respectively. Results presented in this study revealed the reinforcing potential of hybrid nanoparticles that could find application in other polymers as well.

Progress in Nanostructured Mechano-Bactericidal Polymeric Surfaces for Biomedical Applications

Bacterial infections and antibiotic resistance remain significant contributors to morbidity and mortality worldwide. Despite recent advances in biomedical research, a substantial number of medical devices and implants continue to be plagued by bacterial colonisation, resulting in severe consequences, including fatalities. The development of nanostructured surfaces with mechano-bactericidal properties has emerged as a promising solution to this problem. These surfaces employ a mechanical rupturing mechanism to lyse bacterial cells, effectively halting subsequent biofilm formation on various materials and, ultimately, thwarting bacterial infections. This review delves into the prevailing research progress within the realm of nanostructured mechano-bactericidal polymeric surfaces. It also investigates the diverse fabrication methods for developing nanostructured polymeric surfaces with mechano-bactericidal properties. We then discuss the significant challenges associated with each approach and identify research gaps that warrant exploration in future studies, emphasizing the potential for polymeric implants to leverage their distinct physical, chemical, and mechanical properties over traditional materials like metals.

Advanced Injection Molding Methods: Review

Injection molding is a method commonly used to manufacture plastic products. This technology makes it possible to obtain products of specially designed shape and size. In addition, the developed mold allows for repeated and repeatable production of selected plastic parts. Over the years, this technology grew in importance, and nowadays, products produced by injection molding are used in almost every field of industry. This paper is a review and provides information on recent research reports in the field of modern injection molding techniques. Selected plastics most commonly processed by this technique are discussed. Next, the chosen types of this technique are presented, along with a discussion of the parameters that affect performance and process flow. Depending on the proposed method, the influence of various factors on the quality and yield of the obtained products was analyzed. Nowadays, the link between these two properties is extremely important. The work presented in the article refers to research aimed at modifying injection molding methods enabling high product quality with high productivity at the same time. An important role is also played by lowering production costs and reducing the negative impact on the environment. The review discusses modern injection molding technologies, the development of which is constantly progressing. Finally, the impact of the technology on the ecological environment is discussed and the perspectives of the process were presented.

Challenge of material haemocompatibility for microfluidic blood-contacting applications

Biological applications of microfluidics technology is beginning to expand beyond the original focus of diagnostics, analytics and organ-on-chip devices. There is a growing interest in the development of microfluidic devices for therapeutic treatments, such as extra-corporeal haemodialysis and oxygenation. However, the great potential in this area comes with great challenges. Haemocompatibility of materials has long been a concern for blood-contacting medical devices, and microfluidic devices are no exception. The small channel size, high surface area to volume ratio and dynamic conditions integral to microchannels contribute to the blood-material interactions. This review will begin by describing features of microfluidic technology with a focus on blood-contacting applications. Material haemocompatibility will be discussed in the context of interactions with blood components, from the initial absorption of plasma proteins to the activation of cells and factors, and the contribution of these interactions to the coagulation cascade and thrombogenesis. Reference will be made to the testing requirements for medical devices in contact with blood, set out by International Standards in ISO 10993-4. Finally, we will review the techniques for improving microfluidic channel haemocompatibility through material surface modifications-including bioactive and biopassive coatings-and future directions.

Polymeric Denture Base Materials: A Review

An ideal denture base must have good physical and mechanical properties, biocompatibility, and esthetic properties. Various polymeric materials have been used to construct denture bases. Polymethyl methacrylate (PMMA) is the most used biomaterial for dentures fabrication due to its favorable properties, which include ease of processing and pigmenting, sufficient mechanical properties, economy, and low toxicity. This article aimed to comprehensively review the current knowledge about denture base materials (DBMs) types, properties, modifications, applications, and construction methods. We searched for articles about denture base materials in PubMed, Scopus, and Embase. Journals covering topics including dental materials, prosthodontics, and restorative dentistry were also combed through. Denture base material variations, types, qualities, applications, and fabrication research published in English were considered. Although PMMA has several benefits and gained popularity as a denture base material, it has certain limitations and cannot be classified as an ideal biomaterial for fabricating dental prostheses. Accordingly, several studies have been performed to enhance the physical and mechanical properties of PMMA by chemical modifications and mechanical reinforcement using fibers, nanofillers, and hybrid materials. This review aimed to update the current knowledge about DBMs' types, properties, applications, and recent developments. There is a need for specific research to improve their biological properties due to patient and dental staff adverse reactions to possibly harmful substances produced during their manufacturing and use.

Mechanical and Biological Characterization of PMMA/Al2O3 Composites for Dental Implant Abutments

The mechanical and biological behaviors of PMMA/Al2O3 composites incorporating 30 wt.%, 40 wt.%, and 50 wt.% of Al2O3 were thoroughly characterized as regards to their possible application in implant-supported prostheses. The Al2O3 particles accounted for an increase in the flexural modulus of PMMA. The highest value was recorded for the composite containing 40 wt.% Al2O3 (4.50 GPa), which was about 18% higher than that of its unfilled counterpart (3.86 GPa). The Al2O3 particles caused a decrease in the flexural strength of the composites, due to the presence of filler aggregates and voids, though it was still satisfactory for the intended application. The roughness (Ra) and water contact angle had the same trend, ranging from 1.94 µm and 77.2° for unfilled PMMA to 2.45 µm and 105.8° for the composite containing the highest alumina loading, respectively, hence influencing both the protein adsorption and cell adhesion. No cytotoxic effects were found, confirming that all the specimens are biocompatible and capable of sustaining cell growth and proliferation, without remarkable differences at 24 and 48 h. Finally, Al2O3 was able to cause strong cell responses (cell orientation), thus guiding the tissue formation in contact with the composite itself and not enhancing its osteoconductive properties, supporting the PMMA composite's usage in the envisaged application.

Replacing Missing Maxillary Lateral Incisors by CAD/CAM PMMA Cantilever Bridges

Introduction

Management of missing maxillary lateral incisors can be a challenging endeavour for dentists. Whether from agenesis or tooth loss, several treatment modalities are currently present to tackle this task to ensure satisfactory aesthetics. Most patients, especially younger patients are more likely to prefer fixed prosthodontic rehabilitation. Among these options is the computer-aided design and computer-aided manufacturing polymethyl methacrylate (CAD/CAM PMMA) cantilever bridge. Case Descriptions. These two clinical cases describe the management of missing lateral maxillary incisors in two Tunisian female patients with different etiologies, using CAD/CAM PMMA cantilever bridge.

Conclusions

CAD/CAM technologies allow for a fairly quick and simple try-in thanks to their high accuracy as well as being predictable, minimally invasive, and affordable treatment options. This type of restoration can be put to use for mid- to long-term solutions to missing maxillary lateral incisors. However, its success depends mainly on patient selection regarding age, general health, occlusal context, and proper indication.

Fracture Resistance Analysis of CAD/CAM Interim Fixed Prosthodontic Materials: PMMA, Graphene, Acetal Resin and Polysulfone

The aim of this study was to evaluate and compare the fracture resistance of temporary restorations made of polymethylmethacrylate (PMMA), graphene-modified PMMA (GRA), acetal resin (AR) and polysulfone (PS) obtained by a subtractive technique (milling) using a computer-aided design and manufacturing (CAD/CAM) system of a three-unit fixed dental prosthesis (FDP). Methods: Four groups of ten samples were fabricated for each material. Each specimen was characterized by a compression test on a universal testing machine, all specimens were loaded to fracture and the value in Newtons (N) was recorded by software connected to the testing machine. The fracture mode was evaluated on all samples using a stereomicroscope. Results: There were statistically significant differences (p value < 0.005) between PMMA and the other three materials (PMMA: 1302.71 N; GRA: 1990.02 N; RA: 1796.20 N; PS: 2234.97). PMMA presented a significantly lower value than the other materials, and PS showed the highest value. GRA and RA presented a similar range of values but they were still higher than those of PMMA. Conclusions: GRA, RA and PS are presented as valid options within the range of interim milled restorative materials and as alternatives to PMMA.

Biopolymer Composites 2022

Recently, sustainable, biodegradable, and nontoxic materials, especially from renewable resources, have gained a lot of attention, and an important effort has been put into the research of biodegradable and biocompatible polymers as an alternative to petroleum-based commodity plastics [...].