Immobilizing Bactericides on Dental Resins via Electron Beam Irradiation

Abstract

Polymerizable bactericides, such as quaternary ammonium compound–based monomers, have been intensively studied as candidates for immobilizing antibacterial components on dental resin. However, they predominantly exhibit a bacteriostatic behavior, rather than bactericidal, as the immobilized components are left with insufficient molecular movement to disrupt the bacterial surface structure through contact-mediated action. In this study, we developed a novel strategy to increase the density of the immobilized bactericide and enhance its antibacterial/antibiofilm properties by combining a surface-grafting technique with electron beam irradiation. A solution of the quaternary ammonium compound–based monomer, 12-methacryloyloxydodecylpyridinium bromide (MDPB), was coated on polymethyl methacrylate (PMMA) resin specimens at the concentrations of 30, 50, and 80 wt%. The coated resins were subsequently exposed to 10 MeV of electron beam irradiation at 50 and 100 kGy, followed by thermal stabilization at 60 °C. The antibacterial effect was evaluated by inoculating a Streptococcus mutans suspension on the coated PMMA resin samples, which exhibited bactericidal effects even after 28 d of aging ( P < 0.05, Tukey’s honestly significant difference test). Transmission electron microscopy and bacteriolytic activity evaluation revealed that the S. mutans cells had sustained membrane depolarization. Furthermore, the antibiofilm effects against S. mutans and bacteria collected from human saliva were assessed. The thickness and the percentage of membrane-intact cells of the S. mutans and multispecies biofilms formed on the MDPB-immobilized surfaces were significantly lower than the uncoated PMMA specimens, even after 28-d aging ( P < 0.05, Tukey’s honestly significant difference test). Thus, the immobilization of antibacterial MDPB via electron beam irradiation induced rapid membrane depolarization, increasing membrane permeability and eventually causing cell death. Our strategy substantially enhances the antibacterial properties of the resinous materials and inhibits biofilm formation, therefore demonstrating significant potential for preventing infectious diseases in the oral environment.

From Antibacterial to Antibiofilm Targeting: An Emerging Paradigm Shift in the Development of Quaternary Ammonium Compounds (QACs)

“…QAC-based materials and coatings are being actively researched for antibacterial bedding and wound dressings, 162,163 dental materials 147,164,165 and bone cements, 166 biomedical device modification, 148,167,168 effluent treatment, 39,169−171 steel protection against corrosion and marine biofouling, 155,172 and other areas. 173−175 All antibacterial and antibiofilm coatings can be classified as passive, that is, acting only upon direct contact of a pathogenic microorganism with the surface, which includes contact-kill (Figure 10a) or bacteria-repellent (Figure 10b) coatings, or active, that is, releasing an antibacterial agent and destroying plankton cells around surfaces, which includes release-kill coatings (Figure 10c).…”

“…The resistance of dental resins to multispecies biofilm formation was achieved by combining a surface grafting technique with electron beam irradiation. 164 12-Methacryloyloxydodecylpyridinium bromide was used as the QAC-based monomer. Antibacterial and antibiofilm efficacy against Streptococcus mutans and bacteria collected from human saliva have been proven.…”

“…QAC-based materials and coatings are being actively researched for antibacterial bedding and wound dressings, , dental materials ,, and bone cements, biomedical device modification, ,, effluent treatment, ,− steel protection against corrosion and marine biofouling, , and other areas. − …”

“…The resistance of dental resins to multispecies biofilm formation was achieved by combining a surface grafting technique with electron beam irradiation . 12-Methacryloyloxydodecylpyridinium bromide was used as the QAC-based monomer.…”

Interface between Materials and Oral Biology

“…These timely studies address a variety of important issues in oral and craniofacial health. Several articles investigate bacterial adhesion to material surfaces and novel compositions and surface preparation techniques designed to modulate oral biofilm formation (Balhaddad et al, 2021; Lehnfeld et al, 2021; Thongthai et al, 2021). Securing durable adhesion to tooth surfaces using strategies that modify and/or chemically interact with components in the dentin surface is discussed in 3 articles (Alkattan et al, 2021; Cai et al, 2021; Maravic et al, 2021).…”