In this study, new quaternary ammonium bis-phenol A glycerolate dimethacrylate (QABGMA) was synthesized and proposed as a possible antimicrobial dental monomer. Such monomer has the potential to copolymerize with other methacrylate monomers and impart antimicrobial activity in dental resins and other systems. QABGMA monomer was synthesized and incorporated (at 0–15 wt.%) into a 1/1 (wt./wt.) mixture of bisphenol A glycerolate dimethacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA). The mixture was cured by visible light irradiation and degree of conversion (DC) was measured by Fourier Transform Infrared Spectrophotometer (FT-IR). Weight increase and solubility of the cured specimens were measured by immersion in water and ethanol/water solution (75/25, v/v) at 37 ± 1 °C for 30 days. The antimicrobial activity of QABGMA monomer was investigated against Gram-positive bacteria (Streptococcus mutans, Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and a fungus Candida albicans. Finally, cytotoxicity and viability of resin on L929 fibroblast cells were quantified. The incorporated difunctional QABGMA reduced degree of conversion slightly and increased water absorption of the cured polymer. The dental materials obtained from the QABGMA polymerization system showed good antimicrobial activity against tested microorganisms. Also, resin with ⩾10 wt.% QABGMA showed significantly reduced viability.
Here we report preparation and characterization of poly(methyl methacrylate)/silver nanoparticles (PMMA/AgNPs) nanocomposite networks prepared via in situ photoiniferter-mediated photopolymerization (in situ PMP) using tetraethylthiuram disulphide (TED) as photoiniferter and 2,2-dimethoxy-2-phenylacetophenone (DMPA) as photoinitiator. Photopolymerization was performed in the presence of allyl methacrylate, as crosslinking agent, and various amount of silver nanoparticles (AgNPs). AgNPs were synthesized via chemical reduction of silver nitrate with t-BuONa-activated sodium hydride in tetrahydrofuran. The degree of monomer conversion (DC%) during polymerization was followed quantitatively via Fourier transform infrared spectroscopy. DC% of nanocomposite networks slightly increased with AgNPs content. Moreover, differential scanning calorimetry results disclosed a decrease in glass transition temperature (T g) of the nanocomposite networks in comparison with the pure polymer network, suggesting the plasticizing effect of AgNPs. Swelling behaviour was also measured in water and ethanol/water (3/1, v/v) solution at 37 ± 1°C after 30 days. The enhanced swelling ratio for nanocomposite networks with increase in the AgNPs content suggested the potential role of AgNPs in photo-crosslinking reactions. The flexural strength and modulus values resulted from three-point bending method revealed an improvement in mechanical properties of the nanocomposites in comparison with pure PMMA networks. The mechanical behaviour observations were rationalized based on the field emission scanning electron microscopy micrographs from the fractured surfaces of the nanocomposite networks. Finally, thermogravimetric analysis showed that while the AgNPs catalyse the degradation in the early stages, they subsequently act as a retardant agent against thermal degradation.
This study is aimed at the synthesis of antimicrobial hydroxyapatite (HAP)‐based composites for dental application by stereolithography (SLA). A micron‐sized commercial HAP was modified by methacrylate and quaternary ammonium salt, and, then, it was used in different amounts (namely 2.5, 5, and 10 wt%) as filler for a photocurable custom made resin for SLA. Thermal stability, microstructure, and particles size of the pristine (HAP) and modified HAP (mHAP) were evaluated by thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and particle size analyser (CILAS). The suitability of each formulation for stereolithography process was assessed by measuring viscosity, degree of conversion (DC%) by Fourier transform infrared spectroscopy (FTIR), glass transition temperature, and thermal stability. Photo‐cured specimens for physical, mechanical, and antimicrobial testing were built by SLA. The flexural strength of the samples was measured using a 3‐point bending test method, and the fractured surface was analysed by scanning electron microscopy (SEM). The antimicrobial activity of samples was investigated against some standard microorganisms (Staphylococcus aureus, Escherichia coli, and Candida albicans), as representative Gram positive and Gram negative bacteria and fungus, respectively. The flexural strength increased with a filler content up to 5% and slightly decreased for higher content. SEM analysis confirmed the presence of uniformly distributed HAP. The incorporation of mHAP reduced the bacterial and fungal growth in dose‐dependent manner in comparison with the neat samples. Finally, a prototype of dental bite was built by SLA.