In this study, two novel quaternary ammonium urethane-dimethacrylates (QAUDMAs) were designed for potential use as comonomers in antibacterial dental composite restorative materials. QAUDMAs were synthesized via the reaction of 1,3-bis(1-isocyanato-1-methylethyl)benzene with 2-(methacryloyloxy)ethyl-2-decylhydroxyethylmethylammonium bromide (QA10+TMXDI) and 2-(methacryloyloxy)ethyl-2-dodecylhydroxyethylmethylammonium bromide (QA12+TMXDI). Their compositions with common dental dimethacrylates comprising QAUDMA 20 wt.%, urethane-dimethacrylate monomer (UDMA) 20 wt.%, bisphenol A glycerolate dimethacrylate (Bis-GMA) 40 wt.%, and triethylene glycol dimethacrylate (TEGDMA) 20 wt.%, were photocured. The achieved copolymers were characterized for their physicochemical and mechanical properties, including their degree of conversion (DC), glass transition temperature (T_g), polymerization shrinkage (S), water contact angle (WCA), flexural modulus (E), flexural strength (FS), hardness (HB), water sorption (WS), and water leachability (WL). The antibacterial activity of the copolymers was characterized by the minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) against Staphylococcus aureus and Escherichia coli. The achieved results were compared to the properties of a typical dental copolymer comprising UDMA 40 wt.%, Bis-GMA 40 wt.%, and TEGDMA 20 wt.%. The introduction of QAUDMAs did not deteriorate physicochemical and mechanical properties. The WS and WL increased; however, they were still satisfactory. The copolymer comprising QA10+TMXDI showed a higher antibacterial effect than that comprising QA12+TMXDI and that of the reference copolymer.

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.

Six novel urethane-dimethacrylates with quaternary ammonium groups (QAUDMAs) were successfully synthesized from 2-(methacryloyloxy)ethyl-2-hydroxyethylmethylalkylammonium bromide (QAHAMA-n, where n was 8 and 10) and diisocyanate (isophorone diisocyanate (IPDI), 4,4′-methylenedicyclohexyl diisocyanate (CHMDI), and 4,4′-diphenylmethane diisocyanate (MDI)). Their chemical structures were confirmed through nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). The refractive index (RI) and density (d_m) were also determined. The novel QAUDMAs were compounded with common dental dimethacrylates and subsequently photopolymerized. The resulting copolymers, comprising QAUDMA 40 wt.%, bisphenol A glycerolate dimethacrylate (Bis-GMA) 40 wt.%, and triethylene glycol dimethacrylate (TEGDMA) 20 wt.%, were tested for water sorption (WS) and solubility (SL). The WS and SL values decreased following these orderings based on the diisocyanate: IPDI > CHMDI > MDI for WS, and MDI > CHMDI > IPDI for SL. The WS values ranged from 11.50 to 13.82 µg/mm³, and were significantly lower than the recommended maximum for dental materials, 40 µg/mm³. The SL values that met the recommended maximum, 7.5 µg/mm³, ranged from 2.67 to 6.75 µg/mm³. Only the copolymer having the QAHAMA-8- and MDI-derived QAUDMA had the SL slightly exceeding 7.5 µg/mm³, at 7.89 µg/mm³.

Dental caries are treated using dental composite restorative materials (DCRM). However, commercial DCRMs lack antibacterial activity. This research aimed to analyze the in vitro antibacterial activity of a series of copolymers consisting of a urethane–dimethacrylate monomer (UDMA), bisphenol A glycerolate dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA) and urethane–dimethacrylate monomer with two quaternary ammonium groups and a 1,3-bis(1-isocyanate-1-methylethyl)benzene core (QAn+TMXDI, where n = 8, 10, or 12 is the number of carbon atoms in the N-alkyl substituent). QAn+TMXDI contents in copolymers were 20 and 40 wt.%. The results of the Staphylococcus aureus and Escherichia coli adhesion test demonstrated that the logCFU/mL decreased as the length of the N-alkyl chain decreased and QAn+TMXDI content increased. The copolymers of QA8+TMXDI 40 wt.%, Bis-GMA 40 wt.%, and TEGDMA 20 wt.% showed the highest antibacterial activity, with a logCFU/mL of 2.39 for S. aureus and no viable E. coli cells.

We report a one-pot synthesis of well-defined A₅B and A₈B miktoarm star-shaped polymers where N,N-dimethylaminoethyl methacrylate (DMAEMA) and various cyclic esters such as ε-caprolactone (ε-CL), lactide (LA) and glycolide (GA) were used for the synthesis. Miktopolymers were obtained by simultaneously carrying out atom transfer radical polymerization (ATRP) of DMAEMA, ring-opening polymerization (ROP) of cyclic esters, and click reaction between the azide group in gluconamide-based (GLBr₅-Az) or lactonamide-based (GLBr₈-Az) ATRP initiators and 4-pentyn-1-ol. The relatively low dispersity indices of the obtained miktoarm stars (Đ = 1.2–1.6) indicate that control over the polymerization processes was sustained despite almost complete monomers conversions (83–99%). The presence of salts from phosphate-buffered saline (PBS) in polymer solutions affects the phase transition, increasing cloud point temperatures (T_CP) values. The critical aggregation concentration (CAC) values increased with a decreasing number of average molecular weights of the hydrophobic fraction. Hydrolytic degradation studies revealed that the highest reduction of molecular weight was observed for polymers with PCL and PLGCL arm. The influence of the composition on the miktopolymers hydrophilicity was investigated via water contact angle (WCA) measurement. Thermogravimetric analysis (TGA) disclosed that the number of arms and their composition in the miktopolymer affects its weight loss under the influence of temperature.

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.