Izabela Barszczewska-Rybarek

Soft denture lining materials are widely used to improve patient comfort; however, their susceptibility to fungal colonization and concerns regarding phthalate plasticizer use remain major limitations. This study aimed to develop and evaluate a phthalate-free acrylic soft lining material incorporating 2-phenylethyl benzoate (PhB) as a safer plasticizer and 2-(methacryloyloxy)ethyl-2-decylhydroxyethylmethylammonium bromide (QAHAMA-10), a quaternary ammonium-functionalized monomer, as an antifungal component. The synthesized materials with increasing QAHAMA-10 content (7%, 11%, 15% and 18%) were evaluated for their physico-mechanical properties (Shore A0 hardness, tensile strength, tensile bond strength, water sorption, water solubility, and water contact angle), antifungal activity against Candida albicans using adhesion and agar diffusion assays, and cytotoxicity using L-929 fibroblast cells. Incorporation of QAHAMA-10 reduced hardness and surface contact angle while increasing water sorption and solubility; however, tensile strength remained within an acceptable range. The absence of inhibition zones may suggest a predominantly contact-dependent antimicrobial mechanism. All modified materials significantly reduced C. albicans adhesion, with no recoverable CFU detected for SLM3 after both 24 h and 28 days of water storage under the applied assay conditions. All formulations exhibited cell viability above 70%, indicating the absence of cytotoxic effects. Among the tested formulations, SLM3 demonstrated the most favorable balance between antifungal activity, cytotoxicity, and mechanical properties.

Poly(acrylamide) (PAM) hydrogels offer biomedical potential, but bacterial colonization limits their long-term use. This study examines PAM hydrogels modified with quaternary ammonium monomethacrylate (QAHAMA-10) for antimicrobial properties. Five formulations with QAHAMA-10 to acrylamide (AA) molar ratios ranging from 2.5 to 30 mol.% and crosslinked with 1 mol.% N,N′-methylenebisacrylamide (bis-AA) were evaluated. QAHAMA-10 improved hydrogel stability, especially at 10 mol.%, which showed the best structural integrity and transparency. The degree of swelling (DS) decreased with increasing QAHAMA-10 content, from 394.4% (2.5 mol%) to 180.0% (30 mol%), versus 938.4% for the reference. No bacterial growth was detected in suspensions recovered from wells with experimental hydrogels. The hydrogels inhibited Staphylococcus aureus ATCC 25923, with inhibition zones ranging from 16.2 to 23.1 mm depending on the QAHAMA-10 content, while the reference showed no inhibition. In contrast, no activity was observed against Escherichia coli ATCC 25922 in the disk diffusion assay. Alamar Blue reduction in fibroblast L929 cells decreased with higher QAHAMA-10 content, ranging from 70.8% to 27.7% after 24 h and 74.4% to 26.1% after 48 h, compared to 78.1% and 94.2% for the reference. Overall, 2.5 mol.% QAHAMA-10 offered the best balance of anti-S. aureus activity and cytocompatibility, while 10 mol.% provided optimal physicochemical properties.

This study investigates how structural modifications in quaternary ammonium urethane-dimethacrylates (QAUDMAs) affect the physicochemical, mechanical, and biological properties of QAUDMA-containing dimethacrylate copolymers. Specifically, it examines variations in the diisocyanate (DI) core: tetramethylxylene diisocyanate (TMXDI), isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4′-diisocyanate (CHMDI), and diphenylmethane-4,4′-diisocyanate (MDI), as well as the N-alkyl substituent: octyl (QA8) and decyl (QA10). Experimental copolymers were prepared by replacing urethane dimethacrylate (UDMA, 40 wt.%) with QAUDMA in a conventional dental resin system, while retaining bisphenol A-glycidyl methacrylate (Bis-GMA) 40 wt.% and triethylene glycol dimethacrylate (TEGDMA) 20 wt.%. Monomer formulations (40(QAUDMA) _m ) were evaluated for viscosity ( η ), density ( d _m ), and refractive index ( RI ). Copolymers (40(QAUDMA) _p ) were assessed for density ( d _p ), degree of conversion ( DC ), polymerization shrinkage ( S ), glass transition temperature ( T _g ), flexural strength ( FS ), modulus ( E ), hardness ( HB ), in vitro antibacterial activity against Streptococcus mutans, and cytocompatibility using L929 fibroblasts. Monomer mixtures usually retained their physicochemical characteristics, except η , which exhibited higher values than the reference. Copolymers showed improved physicochemical characteristics, while maintaining clinically relevant mechanical performance. Importantly, all 40(QAUDMA) _p s completely prevented bacterial adhesion to the material surface, while maintaining acceptable cytocompatibility, with cell viability above 70% for most formulations. Among the tested systems, TMXDI-based copolymers demonstrated the most balanced overall performance. These results indicate that controlling the DI core structure provides a rational strategy for designing QAUDMA-based resin matrices with tailored antibacterial, mechanical, and biological properties. The obtained structure-property relationships offer valuable insights for the development of functional resin matrices for future dental composite materials.

Bruxism-induced wear and microbial colonization of oral splints remain significant challenges in restorative dentistry. In this study, we developed a series of antibacterial nanocomposites based on a poly(ethylene terephthalate-co-1,4-cyclohexanedimethylene terephthalate) (PET-G) matrix incorporated with zinc oxide (ZnO) particles (3, 7, and 10 wt%), designed for the next generation of oral appliances. The composites were fabricated via a solvent-casting method followed by thermal processing. Differential scanning calorimetry (DSC) revealed that the amorphous nature and glass transition temperature (Tg ≈ 80 °C) of the PET-G matrix remained stable, ensuring excellent processability. While a minor decrease in Shore D hardness and flexural strength (up to 15%) was observed due to filler-induced structural discontinuity, the mechanical integrity remained within clinically acceptable limits. Crucially, the PET-G/ZnO composites exhibited potent antimicrobial activity; the 7 and 10 wt% loadings achieved a 100% reduction in Streptococcus oralis viability and significant inhibition of Candida albicans. These findings demonstrate that ZnO integration provides a dual-functional advantage—maintaining the thermoplastic versatility of PET-G while introducing critical bioactive properties, positioning these materials as a superior alternative for effective long-term bruxism therapy.

The research hypothesis was that adjusting the content of the quaternary ammonium urethane dimethacrylate monomer bearing an N-dodecyl substituent (QAUDMA-12) would yield dental matrices with high antimicrobial activity, good biocompatibility, and favorable physicochemical properties. The research hypothesis was verified for six Bis-GMA, TEGDMA, and UDMA copolymers containing from 2.5 to 40 wt.% QAUDMA-12 by determining their degree of conversion, hardness, flexural properties, water behavior, antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Candida albicans, and cytotoxicity towards L929 mouse fibroblast cells. The research hypothesis was confirmed. Copolymers containing less than 30 wt.% QAUDMA-12 exhibited favorable polymerization efficiency, water sorption and solubility, and mechanical properties comparable to those of conventional Bis-GMA/TEGDMA systems. At the same time, they showed no cytotoxic effects toward mouse fibroblast cells. The results of antimicrobial tests show that the minimum QAUDMA-12 concentration providing sufficient antimicrobial activity was 20 wt.%. Therefore, it can be concluded that the 20 wt.% concentration of QAUDMA-12 makes it possible to obtain dental matrices that are non-toxic, exhibit antimicrobial activity, and possess the desired physico-mechanical performance.

Dental composite reconstructive materials (DCRMs) used in caries treatment possess satisfactory functional properties but lack antimicrobial activity, which may lead to secondary caries. This research aimed to modify the DCRM matrix with urethane-dimethacrylate monomers derived from cycloaliphatic and aromatic diisocyanates bearing quaternary ammonium groups. The diisocyanates used were 1,3-bis(1-isocyanato-1-methylethyl)benzene (TMXDI), isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4′-diisocyanate (CHMDI), and 1,1′-methylenebis(4-isocyanatobenzene) (MDI). As a result, eight modified copolymers were obtained and tested for the surface water contact angle (WCA), water sorption (WS), and water solubility (SL). The WCA results indicated predominantly hydrophilic surfaces, while the WS and SL values were generally satisfactory.

This review examines strategies to enhance the antifungal properties of commercial soft lining materials (SLMs) through modification with plant-derived oils, extracts, and powders. These natural bioactive compounds act via multiple mechanisms, including disruption of fungal cell membranes, inhibition of biofilm formation, and interference with Candida albicans metabolism, the pathogen causing denture-associated candidiasis. Their incorporation into SLM provides localized antifungal activity at the denture–mucosa interface. The review highlights Aloe vera (aloe), Azadirachta indica (neem), Ocimum basilicum (basil), Melaleuca alternifolia (tea tree), Cocos nucifera (coconut), Allium sativum (garlic), Thymus vulgaris (thyme), and chitosan as notable sources of phytotherapeutics that consistently inhibit C. albicans growth. In addition to antimicrobial effects, studies assessed both intrinsic (hardness, tensile strength, tear strength) and interfacial (bond strength) mechanical properties, as well as surface roughness. Most formulations maintained acceptable mechanical performance and improved surface smoothness. Key limitations include rapid leaching of active compounds, variability in testing methods, and insufficient in vivo and cytotoxicity data. Future research should prioritize the high-quality purification of natural extracts, the isolation of well-defined bioactive compounds, and the design of systems enabling selective and sustained release of these agents, ensuring reproducibility, enhanced stability, and clinical reliability of next-generation bioactive SLMs.

Ethylene–vinyl acetate (EVA) is a versatile polymer for applications in dental devices; however, its vulnerability to microbial colonization increases with long-term use. This study evaluates EVA composites modified with silver–sodium–hydrogen–zirconium phosphate (SP) particles, aimed at enhancing antimicrobial performance while preserving key functional properties. Composites containing 1–16 wt.% SP were prepared via solvent-based and mechanical compounding routes, with scanning electron microscopy confirming correct filler distribution across processing methods. Antimicrobial assays revealed a pronounced reduction in Streptococcus mutans and Candida albicans levels, reaching 88% and 98% antimicrobial efficacy, respectively, at 16 wt.% SP. Cytotoxicity testing with L-929 fibroblasts demonstrated maintained cell viability above the 70% threshold, confirming non-cytotoxicity. Mechanical characterization indicated marginal increases in hardness, slight tensile strength reduction at higher filler loadings, while other physicochemical and thermal analyses showed minimal impact on polymer performance. These findings indicate balanced antimicrobial activity with other biofunctional properties.

Dimethacrylate-based dental materials are dominantly used in restorative procedures for their mechanical and esthetic properties. However, they lack inherent antimicrobial activity, making them susceptible to microbial colonization. This has prompted the development of quaternary ammonium dimethacrylate monomers (QADMs) as a counteractive measure. This review critically assesses the tradeoffs associated with the antimicrobial potential, cytocompatibility, and structural performance of QADMs in the past decade. Across the standardized biological assays studied, QADMs consistently exhibit potent antimicrobial activity against cariogenic and opportunistic pathogens without inducing resistance. QADMs maintain favorable mechanical and physicochemical properties upon incorporation into resin composite formulations. Cytotoxicity is structure- and dose-dependent; nonetheless, most QADMs are biocompatible at antimicrobial concentrations. Notably, quaternary ammonium urethane dimethacrylate monomers (QAUDMAs) offer a balanced combination of antimicrobial and structural properties. Few studies have assessed the long-term mechanical durability of QADM-enhanced composites, leaving clinical relevance inconclusive. Further research is necessary to optimize monomer design and clinically validate these materials.

Background: This study aimed to assess the impact of methacrylate-functionalized polyhedral oligomeric silsesquioxanes dispersed in nanosilica (MA/Ns-POSS) on the mechanical properties of light-curable dental resins and composites. The primary goal was to evaluate how different concentrations of MA/Ns-POSS (0.5–20 wt.%) affect the hardness, flexural strength, modulus, diametral tensile strength, polymerization shrinkage stress, and degree of conversion of these materials. Methods: A mixture of Bis-GMA, UDMA, TEGDMA, HEMA, and camphorquinone, with a tertiary amine as the photoinitiator, was used to create resin and composite samples, incorporating 45 wt.% silanized silica for the composites. Hardness (Vickers method, HV), flexural strength (FS), and flexural modulus (E_f) were assessed using three-point bending tests, while diametral tensile strength (DTS) polymerization shrinkage stresses (PSS), and degree of conversion (DC) analysis were analyzed for the composites. Results: The results showed that resins with 10 wt.% MA/Ns-POSS exhibited the highest E_f and FS values. Composite hardness peaked at 20 wt.% MA/Ns-POSS, while DTS increased up to 2.5 wt.% MA/Ns-POSS but declined at higher concentrations. PSS values decreased with increasing MA/Ns-POSS concentration, with the lowest values recorded at 15–20 wt.%. DC analysis also showed substantial improvement for 15–20 wt.% Conclusion: Incorporating MA/Ns-POSS improves the mechanical properties of both resins and composites, with 20 wt.% showing the best results. Further studies are needed to explore the influence of higher additive concentrations.